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
- Development of a lump in the breast or the underarms area
- Abnormal thickening or swelling of the breasts
- Changes in the breast skin
- Changes in the nipples, including redness, flaking, and the inward pull of the nipples
- Abnormal pain in the breast area
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
- 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.
- About 5-10% of breast cancer cases are hereditary.
- Changes in the BRCA1 and BRCA2 genes increase a person’s risk for developing breast cancer.
- Not everyone with BRCA1_ and BRCA2 gene variations may develop breast cancer.
- Breast cancer is more common in women than men - only 1 in 100 men are affected by breast cancer.
- Women who are above> 50 years of age and those with first-degree relatives with breast cancer fall under the high-risk category.
- Other factors like ethnicity, reproductive history, period of breastfeeding, and obesity influence the risk of breast cancer.
- 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
