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.
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.
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.
|T||Higher risk for hyperinsulinemia and breast cancer when physically inactive|
|G||Normal risk for hyperinsulinemia and breast cancer when physically inactive|
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.
|GG||Significant reduction in breast cancer risk with exercise|
|AG||Modest reduction in breast cancer risk with exercise|
|AA||Normal risk of breast cancer with exercise|
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.
|G||Significant reduction in breast cancer risk with physical activity in postmenopausal women|
|A||Normal breast cancer risk with physical activity in postmenopausal women|
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:
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.
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.
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.
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 (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 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 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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
|AA||Increased risk of breast cancer on alcohol consumption|
|GA||Increased risk of breast cancer on alcohol consumption|
|GG||Normal risk of breast cancer on alcohol consumption|
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.
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.
|GG||No risk of breast cancer because of alcohol consumption|
|GT||Increased risk of breast cancer on consuming more than 10g alcohol/day|
|TT||Increased risk of breast cancer on consuming more than 10g alcohol/day|
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.
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.
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.
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.
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.
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.
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.
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.
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 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 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.
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.
Both genetic and non-genetic factors can increase a person’s risk of developing breast cancer.
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 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 also plays a role in the production of tumor suppressor proteins and has 25 SNPs associated with increased breast cancer risk.
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.
Breast cancer is most often found in women. Only 1 % of all breast cancers in the United States are diagnosed in men.
In the United States, white and black women have a higher risk for developing breast cancer than American Indians, Asians, Pacific Islanders, and Hispanics.
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.
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.
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.
Women who have had breast cancer in the past are at higher risk for developing it again.
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.
Women who had radiation exposure in the breasts before the age of 30 have a higher risk for developing breast cancer.
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.
Since obesity is a risk factor for breast cancer, maintaining healthy BMI levels and staying physically active can help bring down the risk.
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.
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.
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.
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.
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
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 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%.
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.
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.
Women who smoke are at higher risk for developing both breast cancer and ovarian cancer.
Post-menopausal obese women are at higher risk for developing breast and ovarian cancers because of higher inflammatory markers in the body.
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.
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.
Since obesity increases your risk for both breast and ovarian cancers, maintaining a healthy weight can help lower your risk.
Being physically active may reduce the risk and improve survival rates for both breast and ovarian cancers.