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How Does Exercise Reduce Breast Cancer Risk?

Regular exercising comes with a range of health benefits, one of which is reduced risk for developing breast cancer. Many studies conducted over the last 20 years have consistently reported a lower risk of breast cancer among women engaging in regular physical activity.

However, the exact mechanism behind this is unclear. Being active may lower estrogen levels in the body. Studies have shown that women with lower blood estrogen levels have a lower risk of breast cancer than women with higher levels.

Adipose tissue is the primary source of estrogen in postmenopausal women. So, reducing body fat with exercise can lower estrogen production and significantly reduce breast cancer risk in postmenopausal women. 

In addition, exercise also reduces inflammation in the body, strengthens the immune system, decreases insulin resistance, and reduces oxidative stress – all of which are risk factors for breast cancer development.

Exercises and Breast Cancer Risk - What Do The Studies Say?

A study published in The Journal of the American Medical Association in 2005 reported that physical activity after breast cancer diagnosis might reduce the risk of death due to the disease. 

Women who performed physical activity equivalent to walking for 3 to 5 hours per week at an average pace benefited the most. 

The study also reported that physical activity after breast cancer diagnosis reduced the chances of recurrence and improved the quality of life in these women. 

The primary reason cited for the reduced risk is the low levels of circulating estrogen.

A study conducted in 2015 reported that weight loss by exercise resulted in an increase in lean mass, greater fitness, and a positive effect on the serum sex hormone levels due to greater loss of body fat. 

These effects have been associated with a decreased risk of postmenopausal breast cancer.

A systematic review analysis was conducted and published in 2019, wherein researchers studied 38 cohort studies published between 1994 and 2017 comprising 68,416 breast cancer cases. 

The researchers observed that the risk for breast cancer was significantly lower in people with exposure to physical activity longer than a year but less than five years, followed by those who had a lifetime exposure to physical activity. 

In a study published in 2014, the authors found that breast cancer and colorectal cancer survivors, who increased their physical activity before or after their cancer diagnosis, showed a decreased mortality risk compared with those who were inactive or did not change their physical activity levels.

How Does Genetics Influence Exercise And Breast Cancer Risk?

The MTRR Gene

5-methyltetrahydrofolate-homocysteine methyltransferase reductase or MTRR gene gives instructions for producing the enzyme methionine synthase reductase, which is required for the normal functioning of enzyme methionine synthase. 

Certain changes in the MTRR gene can induce insulin resistance, thereby making the cells unresponsive to insulin. This can result in type 2 diabetes

Previous studies reported the association of this genetic change with lung and colorectal cancers, but not with breast cancer.

A 2019 study examined the effect of genetically driven insulin resistance on breast cancer risk

The researchers identified a Single Nucleotide Polymorphism (SNP) rs13188458 in the MTRR gene. It was found that, in a group of physically inactive people, those with the T allele of this SNP had a greater risk for abnormally high insulin levels (hyperinsulinemia) and breast cancer than people with the G allele. 

AlleleImplication
THigher risk for hyperinsulinemia and breast cancer when physically inactive
GNormal risk for hyperinsulinemia and breast cancer when physically inactive

The ERCC4 Gene

ERCC Excision Repair 4, Endonuclease Catalytic Subunit or ERCC4 plays an essential role in repairing damaged DNA. A defect in this gene has been associated with Xeroderma pigmentosa, a skin condition.

A meta-analysis done in 2011 revealed an association between ERCC4 and breast cancer risk. rs1800067 is an SNP in the ERCC4 gene. 

Postmenopausal women with the GG genotype of this SNP who engaged in >9.23 hours of recreational physical activity per week experienced statistically significant reductions in breast cancer risk.

GenotypeImplication
GGSignificant reduction in breast cancer risk with exercise
AGModest reduction in breast cancer risk with exercise
AANormal risk of breast cancer with exercise

The MLH1 Gene

The MLH1 or MutL homolog 1 gene is a part of MMR or mismatch repair set of genes. It repairs damaged DNA by replacing the portion containing the errors with the corrected sequence. 

rs1799977 is an SNP in the MLH1 gene. Women with the G allele of this SNP who were active during the postmenopausal years experienced significant breast cancer risk reductions.

AlleleImplication
GSignificant reduction in breast cancer risk with physical activity in postmenopausal women
ANormal breast cancer risk with physical activity in postmenopausal women

How To Reduce Your Risk of Breast Cancer with Exercise

Researchers have observed that postmenopausal women who exercise for at least 300 minutes per week can successfully reduce their body fat compared to those who spent half that time. 

Even 2.5 hours of brisk walking per week can reduce breast cancer by as much as 18%!

If you are in a dilemma about how to begin your exercise, here are some handy and effective tips to help you exercise the right way to keep breast cancer at bay:

Video

Summary

  1. Studies have consistently reported lower breast cancer risk among women who exercise regularly.
  2. Exercising reduces the estrogen levels in the body, thereby reducing your breast cancer risk.
  3. Several studies report a positive effect of exercising, not only on breast cancer risk but also on breast cancer prognosis and survival.
  4. People with a certain genetic type tend to benefit more in terms of breast cancer risk reduction with exercises.
  5. Brisk walking for even 2.5 hours per week could bring down breast cancer risk by 18%!
  6. Aerobic exercises like jogging, cycling, and swimming also seem to be effective in reducing breast cancer risk. 

References:

Menarche marks the beginning of the first menstrual cycle. This is a significant event of puberty and helps the body prepare for reproduction. According to the National Health Statistics Report, the mean age of menarche in the United States between 2013 and 2017 was 12.5. Globally, the mean age of menarche is about 13. 

The Relationship Between Menstrual Cycles And Breast Cancer Risk

Menarche marks the beginning of the production of female reproductive hormones. These hormones circulate in the body until menopause. During the reproductive years of a woman (the period between menarche and menopause), the levels of the two steroid hormones, estrogen and progesterone, keep fluctuating. 

The progesterone levels increase during the luteal phase. It is the highest during the mid-luteal phase and decreases when periods start. Progesterone is responsible for thickening the endometrium walls and preparing the body for a possible pregnancy. The estrogen levels increase twice during each menstrual cycle - once during the mid-follicular phase and once during the mid-luteal phase. 

The follicular phase is the phase between the first day of menstruation and the next ovulation day. It lasts between 14 and 16 days. The luteal phase is the phase after ovulation until the next menstrual cycle. This lasts for 11-17 days.

The lifetime cumulative number of menstrual cycles is a term that denotes the total number of menstrual cycles a woman experiences in her lifetime. With increased menstrual cycles, the woman’s exposure to estrogen and progesterone also increases. These hormones circulate the breast tissues and increase the risk of developing breast cancer. 

Therefore, the number of menstrual cycles a woman has is a risk factor for developing breast cancer. 

Studies show that women who have regular and shorter menstrual cycles have a higher risk for breast cancer than those with longer cycles. 

These studies also report that women who had more menstrual cycles before their first full-term pregnancy were at higher risk for breast cancer. 

A population-based study analyzed the relationship between the number of menstrual cycles a group of 6718 women had before menopause and their risk of breast cancer. The study reports that women who had more menstrual cycles and hence more exposure to estrogen were at higher risk for breast cancer. 

Age Of Menarche And Breast Cancer Risk

With early menarche, women have increased exposure to estrogen and progesterone. For instance, assuming the menopausal age to be 50, a woman with a menarche age of 11 has a 39-year exposure to the hormones. On the other hand, another woman with a menarche age of 17 only has a 33-year exposure to the hormones. 

A study analyzed serum estrone (E1) and estradiol (E2) levels in postmenopausal women. The study shows that women with a late menarche age (later than 17 years) had significantly lesser amounts of E1 and E2 levels after menopause. This brought down their risk of breast cancer.

A meta-analysis studied the relationship between menarche age and risk of breast cancer in 118,964 women with a breast cancer diagnosis across 117 studies. According to the meta-analysis, breast cancer risk increases slightly for each year earlier menstruation begins (by about 5%).

Another study reported that women with a menarche age of 11 or lower had a 15-20% higher chance of developing breast cancer than women with a menarche age of 15 or higher. 

Age Of Menarche & Breast Cancer Risk: Genetic Factors

Changes in the functioning of specific genes (genetic polymorphisms) can increase or decrease the menarche age and, as a result, increase or decrease the risk of breast cancer. 

The INHBA Gene 

The INHBA gene (Inhibin, beta A gene) helps produce the INHBA protein. This protein plays a role in controlling the production of the Follicle-Stimulating Hormone (FSH). FSH increases and decreases during each menstrual cycle and plays a role in the maturation of the reproductive system.

rs1079866 is a single nucleotide polymorphism or SNP in the INHBA gene. It has been associated with breast cancer risk. The C allele of this SNP has been associated with lower age of menarche and increased risk of breast cancer. 

In women with a lower menarche age, the SNP rs1079866 of this gene showed an increased risk of developing breast cancer. People with this SNP had a per-risk-allele odds ratio of 1.14.  

The PXMP3 Gene 

The PXMP3 gene helps produce the PXMP3 protein (peroxisomal membrane protein 3). The A allele of the SNP rs7821178 is associated with a higher risk of breast cancer in women with early menarche ages. 

The LEP Gene

The LEP gene helps produce a hormone called leptin. Leptin is responsible for maintaining body weight and controlling fat stores. Leptin also plays a role in fertility and the initiation of puberty. 

People with the AA genotype of the SNP rs7799039 of this gene have early menarche and an increased risk of breast cancer. 

Recommendations To Reduce Breast Cancer Risk

Maintain a healthy weight from a younger age 

Studies show an inverse relationship between Body Mass Index (BMI) levels and menarche age. Younger girls who fall under the overweight and obese categories get their first menstrual cycle very early. This can increase the risk of breast cancer in girls as they grow up. Maintaining healthy BMI levels from a very young age can help women lower breast cancer risk.

Be Physically Active

Girls who were physically active as they grew up have significantly delayed menarcheal age compared to girls who did not have much physical activity. A Canadian study reports that girls who participated in dance, swimming, figure skating, and diving competitions had a lower risk of reaching early menarcheal age. Adequate physical activity will help bring down the risk of breast cancer as the girls grow up. 

Avoid Exposure to Tobacco Smoke 

A 2004 study analyzed the effects of tobacco smoke exposure in little girls and their menarcheal age. According to the study, girls who had high exposure to prenatal smoke and secondhand smoke had early menarche compared to girls who were not exposed to tobacco smoke. 

Early menarche age and the inhalation of carcinogenic chemicals from tobacco smoke can both increase the girl’s risk of breast cancer when she grows up.  

Increase Plant Food Intake

A small-scale study analyzed the effects of nutrition on menarche age. According to the study, girls who consumed more animal proteins than plant proteins between the ages of 3 and 5 had earlier menarche. 

Another study reported that girls who consume isoflavones, a type of isoflavonoid (plant compound) produced by the bean family, experience slightly delayed menarche. Soybeans, chickpeas, peanuts, and pistachios are rich in isoflavones. 

Summary

  1. Menarche is the age at which the first menstrual cycle occurs. This is the main event for puberty and the maturation of the female reproductive system. 
  2. Menstrual cycles cause an increase in the steroid hormones estrogen and progesterone in the female body. Increased lifetime menstrual cycles in a woman increases her exposure to these hormones and increases the risk of breast cancer.
  3. Early menarche also increases a woman’s lifetime exposure to estrogen and progesterone, increasing the risk of breast cancer.
  4. Changes in the INHBA gene, PXMP3 gene, and LEP gene can all increase or decrease the menarche age and, therefore, increase or decrease the risk of breast cancer.
  5. Maintaining healthy BMI levels, getting adequate physical activity, and staying away from tobacco smoke can all help delay menarche age and reduce breast cancer risk. 

References

According to the 2019 National Survey on Drug Use and Health (NSDUH) report, 85.6% of people in the United States who are 18 or older had consumed alcohol at some point in life.

51% of women reported that they consumed alcohol in the past month.

While alcohol consumption causes many health problems, it is also a risk factor for breast cancer.

Breast cancer is the most common type of cancer affecting millions of women globally. In the United States, 1 in every eight women will develop invasive breast cancer in her lifetime. 

There are few reasons why researchers think alcohol consumption is related to breast cancer.

  1. The role of acetaldehyde (AA)

When a person consumes alcohol (ethanol), it goes through multiple detoxification pathways and uses several enzymes. One such enzyme is alcohol dehydrogenase (ADH). ADH converts ethanol to AA. AA is carcinogenic (cancer-causing) and needs to be quickly eliminated from the body. 

While ADH is primarily expressed in the liver, it is also found in small quantities in the breast tissue. ADH converts ethanol into AA in the breast tissues and causes abnormal DNA changes, leading to breast cancer.

  1. Increased estrogen levels

Alcohol can increase estrogen levels in the body. A particular study reported that when compared to women who don’t drink, pre-menopausal women who drink have an 18% increase in serum estrogen levels.  

The body uses CYP enzymes to clear out excess estrogen from the body. These enzymes convert estrogen into intermediaries that are then removed from the body. This conversion process releases free radicals that can cause cell DNA abnormalities and increase the risk of cancers, including breast cancer. 

Higher levels of estrogen in the body can also increase the activity of the Estrogen Receptor α (ERα) protein. This protein attaches itself to the DNA and controls various genes. Increased ERα activity leads to increased cell division and growth (cell proliferation), increasing the chance of cell damage and resultant cancer. 

Alcohol And Breast Density Marker

Breast density or mammographic density is a measure of the type of tissues that make up the breasts. Breasts contain fat tissues, glandular tissues (tissues that help make breast milk), and connective tissues. 

People with high glandular and connective tissues in the breast and less fatty tissues have high breast density. On the contrary, people with high levels of fat tissues, when compared to glandular and connective tissues, have low breast density.

According to a meta-analysis that looked into more than 42 studies, women with more than 75% breast density had up to 5 times higher risk for developing breast cancer than women with less than 5% breast density.

On mammograms (X-rays to examine human breasts), fatty tissues look dark, and connective and glandular tissues look clear or white. Cancer cells also appear white. As a result, cancer cells may be hidden on mammograms until they have grown or spread in people with higher breast density. This makes breast cancer treatments more complicated.

A study interviewed 262 women in New York and analyzed their mammograms and alcohol intake pattern. According to the study, women who drank at least seven drinks a week had a 12.3% higher breast density than women who don’t drink.

Another 2015 study analyzed the relationship between drinking patterns and breast density in 189 women. This study also reported that women who drank more than seven drinks a week had higher breast density than those who did not drink. 

Alcohol Metabolizing Genes & Breast Cancer Risk

ALDH2 Gene 

The ALDH2 gene helps produce the Aldehyde dehydrogenase (ALDH) enzyme. Changes in the gene can lead to problems in the production of the ALDH enzyme. This enzyme helps in clearing alcohol from the body.

According to studies, people with the AA and GA genotype of the Single Nucleotide Polymorphism (SNP) rs671 of this gene have a higher risk for developing breast cancer when they consume alcohol than people with the GG genotype. 

GenotypeImplication
AAIncreased risk of breast cancer on alcohol consumption
GAIncreased risk of breast cancer on alcohol consumption
GGNormal risk of breast cancer on alcohol consumption

CYP2E1 Gene

The CYP2E1 gene helps produce the CYP2E1 enzyme. This enzyme helps in clearing up to 20% of ethanol in the brain.

According to a Korean study, women who had the CYP2E1 c2 allele and drank at least once a month had a 1.9-fold increased risk for developing breast cancer than non-drinking women with the CYP2E1 c1/c1 genotype. 

GSR gene

The GSR gene (Glutathione-Disulfide Reductase gene) helps produce the GSR enzyme. This enzyme helps in preventing oxidative stress and cell damage in the body.

The SNP rs1002149 in this gene is associated with breast cancer risk on alcohol intake.  The T-carriers of this SNP showed a 24% higher risk for developing breast cancer when they consumed more than 10 grams of alcohol a day. The GG carriers did not show such a risk.

GenotypeImplications
GGNo risk of breast cancer because of alcohol consumption
GTIncreased risk of breast cancer on consuming more than 10g alcohol/day
TTIncreased risk of breast cancer on consuming more than 10g alcohol/day

Alcohol & Breast Cancer: Non-Genetic Risk Factors

Number Of Drinks And Drinking Pattern 

The risk for breast cancer increases with an increase in alcohol consumption. A meta-analysis of 53 reports reported the following.

The study also suggested that the risk of breast cancer increased by 7% for every additional drink the woman has had per day 

It is not enough to calculate the number of drinks to analyze the risk for breast cancer. The drinking patterns should also be taken into account.

Drinking multiple alcoholic beverages in the same sitting is considered riskier than consuming moderate quantities over the week. For instance, a woman who has seven drinks over the weekend and refrains from drinking on weekdays is at higher risk for breast cancer than a woman who has one drink a day. 

Age 

Studies show that early-life exposure to environmental carcinogens increases a woman’s risk of developing cancer. The age between menarche (the first menstrual cycle) and the first pregnancy is considered a high-risk period. 

Women who drink excessively or take up binge drinking at an early age are more affected by alcohol during this period and are at a higher risk of being diagnosed with breast cancer in the future. 

Type Of Alcohol Consumed

Different types of alcohol have different levels of ethanol content in them. This can increase or decrease the risk of developing breast cancer. Also, certain alcoholic beverages like red wine have antioxidant properties that can protect against cancers to an extent.

A small study reported that resveratrol, a type of polyphenol (plant-compound) found in red wine, can bring down estrogen production in the body and decrease the risk of developing breast cancer. Red wine also seems to help reduce breast density in young premenopausal women. 

Another study talks about the chemoprotective effects of beer. Beer contains the pods of a coneflower called hop that gives the drink its bitterness and flavor. Hops contain substances like xanthohumol and hop-bitter acids that may have cancer-preventing abilities. 

Please Be Advised: Alcohol consumption more than your daily dose can increase your risk of accident, injury or hangover.

Recommendations To Reduce Breast Cancer Risk

Limit Alcohol Intake

Some people just cannot completely avoid drinking. Drinking in moderation may help in such cases. Taking one or lesser drink per day can help bring down the risk of breast cancer. 

Avoid Binge Drinking

When the body suddenly processes excess alcohol, it struggles and leads to excess production of acetaldehyde and estrogen. 

Avoid binge drinking and split your alcohol dosage evenly throughout the week. According to the National Institute on Alcohol Abuse and Alcoholism, binge drinking in women equals consuming more than four drinks in 2 hours.

Avoid Alcohol Use During Adolescence And Early Adulthood

Early exposure to alcohol, especially between the periods of menarche to the first pregnancy, can cause irreparable damage to the breast cells. Several studies have shown that the breast cells are easily damaged/altered by environmental factors in the early periods. 

In the United States, the minimum drinking age is 21. However, reports show that 1 in 4 women aged between 12-20 have consumed an alcoholic beverage in the last month. 

Women who have started drinking before 25 years seem to be at a higher risk for developing breast cancer than women who started later. 

Avoid consuming alcohol before 21 and limit the number of drinks you consume after the legal age. 

Undergo Genetic Testing

Breast cancer is a result of several genetic and environmental factors, and alcohol consumption is just one of them. Genetic testing will tell you if you are genetically at a higher risk for developing breast cancer. If so, you may want to control the environmental factors better. 

If you belong to the high-risk category, getting a mammogram periodically helps too. 

Video

Summary

  1. Alcohol consumption is associated with many health conditions, including breast cancer. 
  2. Ethanol in drinking alcohol increases the production of acetaldehyde (AA) and estrogen in the body. In excessive amounts, these lead to cell damage, abnormal cell division and growth, and the development of cancer. 
  3. Alcohol also increases breast density. Breast density is associated with an increased risk of breast cancer. High breast density also makes it challenging to identify tumors in their early stages.
  4. Changes in the ALDH2, CYP2E1, and the GSR genes can increase or decrease a person’s risk of developing breast cancer on alcohol consumption. 
  5. The number of drinks had, the drinking pattern, age during alcohol consumption, and the type of drink consumed can all affect a person’s risk for developing breast cancer.
  6. Choosing the right drink, avoiding binge drinking, limiting alcohol intake, and opting for genetic testing can help bring down breast cancer risk.

Early-Onset Breast Cancer

Breast cancer usually occurs in women around the age of 50. However, in some women, breast cancer develops around 18-45 years of age, a condition called early-onset breast cancer. According to the Center for Disease Control, 1 in 10 women who are diagnosed with breast cancer is under the age of 45.

Another report from JAMA 2015 notes that 15% of deaths due to breast cancer occur in women whose disease was detected before 45 years of age. Early-onset breast cancers are generally hereditary but are often diagnosed late. Some of these cancers are also very aggressive and difficult to treat.

Genetic Risk Factors for Early Onset Breast Cancer

Since early-onset breast cancer has a strong hereditary influence, genetics plays an important role in its development. Most women diagnosed with early-onset breast cancer have a family member who has or has had breast or ovarian cancer. Having a male member with a history of breast cancer also increases their risk.

Some genes that have shown to increase risk are:

The BRIP1 Gene

The BRCA1 Interacting Protein C-terminal Helicase 1 or BRIP1 gene contains instructions for producing tumor suppressor proteins. Changes in this gene are associated with breast cancer and Fanconi’s Anemia, a type of early childhood cancer syndrome. The BRIP1 gene, along with the BRCA1 gene, helps repair damaged DNA. The damaged parts of the DNA are removed and the remaining structure is restored to health.

The FGFR2 Gene

The Fibroblast Growth Factor 2 or FGFR2 is a gene that produces proteins to regulate fibroblast growth factors. These growth factors participate in cell growth and multiplication. Mutations or changes in the FGFR2 gene have been associated with multiple types of cancers, including breast, lung, and ovarian cancer.

Non-Genetic Factors Influencing Early Onset Breast Cancer Risk

Recommendations to Lower Risk of Early-Onset Breast Cancer

Summary

  1. Though breast cancer is commonly seen in women over 50 years of age, it can occur in women much earlier, between 18-45 years. This is known as early-onset breast cancer.
  2. Early-onset breast cancer occurs in women with a strong family history of breast or ovarian cancer in their family.
  3. Multiple genes have been identified to increase a woman’s risk for early-onset breast cancer. Some of these include BRIP1, MAP3K1, and CASC21.
  4. Some non-genetic factors like race, descent, previous exposure to radiation to the chest, and non-cancerous breast growths can also increase women’s risk for early-onset breast cancer.
  5. If a woman has a family member with a history of breast or ovarian cancer, it is important to opt for genetic testing, genetic counseling, and regular breast screenings.

References

https://www.cdc.gov/cancer/videos/breast/bringyourbrave/earlyonsetbreastcancer/introduction-riskfactors/introduction-riskfactors-ADTranscript-508.pdf
https://www.hopkinsmedicine.org/breast_center/breast_cancers_other_conditions/family_history_breast_cancer.html
https://www.genecards.org/cgi-bin/carddisp.pl?gene=BRIP1
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3109611/
https://pubmed.ncbi.nlm.nih.gov/24780616/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5666331/
https://www.nature.com/articles/srep12773
https://pubmed.ncbi.nlm.nih.gov/30515698/
https://www.nature.com/articles/srep12773
https://www.cancer.org/cancer/breast-cancer/screening-tests-and-early-detection/american-cancer-society-recommendations-for-the-early-detection-of-breast-cancer.html

Breast cancer develops as a result of abnormal growth and development of cells in the breast tissue. The breast is made up of three important parts:
- Lobules: Milk-producing glands
- Ducts: Tube-like parts that carry milk from lobules to the nipples
- Connective tissues: Tissues that surround the breast

Abnormal cell growth can occur in any of the three parts but is more commonly seen in the lobules and ducts.

Sometimes the cancer cells can spread to other parts of the body via the lymph system or blood, resulting in metastasized cancer.

Around the world, breast cancer affects 12% of women. It is also the leading cause of cancer deaths in women - 14% of all cancer-related deaths in women are because of breast cancer.

Symptoms of Breast Cancer

Both genetic and non-genetic factors can increase a person’s risk of developing breast cancer.

Genetic Factors Increasing Breast Cancer Risk

About 5-10% of breast cancer cases are thought to be hereditary. Women with first-degree relatives affected with breast cancer fall under the high-risk category for developing the condition.

Changes or mutations in two genes - BRCA1 and BRCA2 are majorly associated with breast cancer risk. Both these genes help make tumor suppressor proteins and are beneficial to the body. Tumor suppressor proteins prevent the abnormal growth and division of cells.

Changes in these genes result in less or abnormal production of tumor suppressor proteins and thereby increase the risk of developing all kinds of cancers, including breast cancers.

Having a mutation in these genes does not mean that the individual will be diagnosed with breast cancer. These mutations just indicate high risk and warrant further investigation and close monitoring.

The BRCA1 Gene

The BRCA1 gene contains instructions for the production of tumor suppressor proteins. Other than preventing abnormal cell growth, the tumor suppressor proteins also:
Interact with other proteins to repair damaged DNA
Regulate the activity of other genes
Prevent damaged DNA from getting passed on to other healthy cells
There are 25 SNPs or Single Nucleotide Polymorphisms in the BRCA1 gene, that play a role in increasing the risk of breast cancer.

The BRCA2 Gene

The BRCA2 gene also plays a role in the production of tumor suppressor proteins and has 25 SNPs associated with increased breast cancer risk.

Non-genetic Factors Influencing Breast Cancer Risk

Age

Men and women who are more than 50 years of age are at higher risk for developing breast cancer than younger individuals. Women aged 70-74 fall under the highest risk category.

Gender

Breast cancer is most often found in women. Only 1 % of all breast cancers in the United States are diagnosed in men.

Ethnicity

In the United States, white and black women have a higher risk for developing breast cancer than American Indians, Asians, Pacific Islanders, and Hispanics.

Dense Breasts

Tumorous cell growth is difficult to detect in women with dense breasts because of increased connective tissues. Such women are at higher risk of developing more complications because of late diagnosis.

Reproductive History

Girls who get their menstrual periods before 12 years of age are at higher risk for developing breast cancer as they grow older. Similarly, women who experience late menopause (after 55 years of age) are at higher risk for breast cancer.

Age During the First Full-term Birth

According to a worldwide study, women who give birth to their first full-term child early seem to be more protected against breast cancer. Women who had their first child after 35 had a 22% increased risk for developing breast cancer.

Personal History of Breast Cancer

Women who have had breast cancer in the past are at higher risk for developing it again.

Breastfeeding Duration

A population-based study analyzed the effects of breastfeeding on breast cancer risk in 553 women. According to the study, women who breastfed their babies for more than 13 months had a significantly lesser risk for developing breast cancer.

Radiation Therapy Exposure

Women who had radiation exposure in the breasts before the age of 30 have a higher risk for developing breast cancer.

Obesity

Post menopausal women who are obese are at higher risk of developing breast cancer than women with normal BMI levels. Obese women with breast cancer have worse disease progression and lower overall survival rates.

Recommendations To Reduce Breast Cancer Risk

Maintain A Healthy Weight and Stay Physically Active

Since obesity is a risk factor for breast cancer, maintaining healthy BMI levels and staying physically active can help bring down the risk.

Quit Smoking

Women who have started smoking during adolescence are at very high risk for developing breast cancer. A study done in the United Kingdom analyzed 102,927 women who smoked. A follow-up study done after of 7.7 years, revealed that 1815 of these women had developed breast cancer.

Limit Alcohol Intake

Studies show that women who consume even moderate amounts of alcohol regularly are at 30-50% higher risk for developing breast cancer.
For women who are already in the high-risk category, alcohol consumption adds to the risk.

A study recruited 89,538 women aged 34-59 years with no prior history of cancer. The study recorded and monitored their alcohol consumption history. In the next four years, 601 cases of breast cancer were diagnosed in the study group.

The risk of breast cancer was relatively higher in women who consumed more than three drinks a week.

Consult a Genetic Counselor

Genetic testing for mutations in the BRCA1 and BRCA2 genes will tell you if your breast cancer risk is higher than normal. If you are at a higher risk, talk to a counselor to understand how you can handle the risk. You may be asked to go through breast cancer screening more frequently to help with early diagnosis.

Summary

  1. The growth and development of abnormal cells in the breast tissues is called breast cancer. Breast cancer can develop in the lobules, ducts, or connective tissues in the breasts.
  2. About 5-10% of breast cancer cases are hereditary.
  3. Changes in the BRCA1 and BRCA2 genes increase a person’s risk for developing breast cancer.
  4. Not everyone with BRCA1_ and BRCA2 gene variations may develop breast cancer.
  5. Breast cancer is more common in women than men - only 1 in 100 men are affected by breast cancer.
  6. Women who are above> 50 years of age and those with first-degree relatives with breast cancer fall under the high-risk category.
  7. Other factors like ethnicity, reproductive history, period of breastfeeding, and obesity influence the risk of breast cancer.
  8. Maintaining healthy BMI levels, limiting alcohol, quitting smoking, and getting yourself screened for BRCA1 and BRCA2 gene variations can help reduce the risk of breast cancer.

References:

https://www.cdc.gov/cancer/breast/index.htm
https://www.cdc.gov/cancer/breast/basic_info/risk_factors.htm
https://www.cancer.org/cancer/breast-cancer/about/what-is-breast-cancer.html
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4491690/ https://www.cdc.gov/cancer/breast/men/index.htm
https://www.cancercenter.com/community/blog/2019/07/whats-the-difference-female-male-breast-cancer
https://pubmed.ncbi.nlm.nih.gov/5312521/
https://medlineplus.gov/genetics/gene/brca2/#conditions

Breast Cancer is cancer that starts in the breast cells. In the United States, about 1 in 8 women will develop breast cancer in their lifetime.

Ovarian cancer refers to the abnormal growth and multiplication of cells in the ovarian tissues. This is the 10th most common cancer type affecting women in the U.S.

Cancer is the number one cause of death in Americans. In women, both breast and ovarian cancers increase the mortality rate significantly.

Symptoms of Breast Cancer

Symptoms of Ovarian Cancer

Ovarian cancer does not show symptoms until cancer begins to spread, making it more difficult to treat. Some of the of advanced-stage ovarian cancer are:
- Abdominal pain
- Bowel movement changes
- Frequent urination
- Loss of appetite
- Weight loss

Hereditary Breast and Ovarian Cancer Syndrome

The Hereditary Breast and Ovarian Cancer Syndrome (HBOC) is a genetic condition that increases women’s risk of developing breast and ovarian cancers.

HBOC may be suspected if a person has the below personal/family history.
First or second-degree relatives with both breast cancer and ovarian cancer: 10-20% of patients with breast cancer and ovarian cancers have a family history of either/both the types of cancer.
Genetic mutation (changes) in both the BRCA1 and BRCA2 genes
Breast cancer diagnosis before the age of 50
Breast cancer diagnosis and Ashkenazi Jewish ancestry

BRCA1 and BRCA2 genes

BRCA1 and BRCA2 genes contain instructions for the production of tumor suppressor proteins.

These proteins prevent abnormal growth and division of cells and bring down the risk of cancers. Changes in these genes are very closely associated with breast cancer and ovarian cancer.

However, changes in these genes may not always lead to breast and ovarian cancer. It just means that women with these genetic mutations are at a higher risk of developing breast and ovarian cancer.

Genetic changes in either of these genes result in a breast cancer risk of 60-85% and an ovarian cancer risk of 15-40%.

Non-Genetic Factors That Increase The Risk Of Breast and Ovarian Cancers

Age

Women between the ages 70-74 have the highest risk for breast cancer. Women between the ages of 55 and 64 have the highest risk for developing ovarian cancer.

Ethnicity

In the United States, white and black women have a higher risk for developing breast cancer than American Indians, Asians, Pacific Islanders, and Hispanics. Whites and non-Hispanics have a higher risk for developing ovarian cancer than Asians, Pacific Islanders, and Hispanics.

Lifestyle Habits

Women who smoke are at higher risk for developing both breast cancer and ovarian cancer.

Obesity

Post-menopausal obese women are at higher risk for developing breast and ovarian cancers because of higher inflammatory markers in the body.

Age At First Birth

Women who had their first child after 35 had a 22% increased risk for developing breast cancer.
Similarly, women who have never had children or those who get pregnant after 35 have a higher risk for developing ovarian cancer.

Recommendations To Bring Down Breast and Ovarian Cancer Risk

Genetic testing

A BRCA genetic test can help you identify your genetic risk for breast and ovarian cancer. If any of your first or second-degree relatives have been diagnosed with breast cancer, ovarian cancer, or both in the past, then genetic testing is highly recommended. Your healthcare provider and a genetic counselor can help you understand risk assessment and the implications of the test.

Maintain a Healthy Weight

Since obesity increases your risk for both breast and ovarian cancers, maintaining a healthy weight can help lower your risk.

Regular Physical Activity

Being physically active may reduce the risk and improve survival rates for both breast and ovarian cancers.

Summary

  1. The Hereditary Breast and Ovarian Cancer Syndrome (HBOC) is a genetic syndrome that increases a woman’s risk of developing breast and ovarian cancers.
  2. Genetic variations in the BRCA1 and BRCA2 genes can increase your risk for breast and ovarian cancer.
  3. Having first and second relatives with breast and ovarian cancer can also increase your breast cancer risk.
  4. Other risk factors for breast and ovarian cancer include smoking, obesity, and Ashkenazi Jewish ancestry.
  5. BRCA genetic testing is recommended for at-risk women.
  6. Maintaining a healthy weight, quitting smoking, and planning a pregnancy before 35 can help bring down the risk for breast and ovarian cancers.

References

https://www.ncbi.nlm.nih.gov/books/NBK1247/
https://pubmed.ncbi.nlm.nih.gov/12788999/
https://stanfordhealthcare.org/medical-conditions/cancer/hboc.html
https://rarediseases.org/rare-diseases/hereditary-breast-ovarian-cancer-syndrome/
https://gis.cdc.gov/Cancer/USCS/DataViz.html
https://www.cancer.org/cancer/ovarian-cancer/about/key-statistics.html

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