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Genetics of Breast Cancer- An Overview

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4 min read


Breast cancer can have a genetic component. Read this article to know about it in detail.

Medically reviewed by

Dr. Rajesh Gulati

Published At August 30, 2023
Reviewed AtAugust 30, 2023


Human tumorigenesis (the process of formation of uncontrolled growing cells) is a multi-step process that reflects genomic changes in the gene that predisposes to cancer and causes cell and gene changes that start and accelerate the development of the disease. The "cancer phenotype" is determined by how the cancer genome manifests. Cancer phenotype is a classification system for a group of characteristics that result from a genotype's interaction with its environment. Cancer is more than just the tumor (uncontrolled growing cell) cell; it is a local ecosystem made up of numerous physiologic changes in cells that collectively control malignant growth. These changes include self-sufficiency in growth signals, insensitivity to growth-inhibitory (antigrowth) signals, evasion of programmed cell death (apoptosis), unlimited potential for replication, sustained angiogenesis, tissue invasion, and metastasis (a process in which cancerous cells spread to one part of the body to the another). This article explains the link between genes and breast cancer.

What Is Breast Cancer?

Breast cancer is a type of cancer that forms in the cells of the breast. It occurs when the cells in the breast grow and divide uncontrollably, forming a tumor. Both men and women can develop breast cancer, but it is more common in women. There is still much to learn about the precise causes of breast cancer, but certain risk factors can increase the likelihood of developing the disease. These risk factors include age, breast cancer in the family, inherited gene alterations (such as the BRCA1 mutation and BRCA2), personal history of breast cancer or certain benign breast conditions, hormonal factors (such as early menstruation or late menopause), exposure to estrogen, obesity, alcohol consumption, and radiation exposure.

Early-stage breast cancer may not cause any symptoms, so regular breast self-exams, clinical breast exams, and mammograms are essential for early detection. As the disease progresses, common symptoms can include changes, such as a lump or thickening in the breast or armpit in size or shape, nipple changes or discharge, skin changes (such as dimpling, redness, or scaling), and breast pain.

Breast cancer can be classified into different types based on the cells involved, such as ductal carcinoma (most common), lobular carcinoma, or less common types like inflammatory breast cancer or Paget's disease of the nipple. The treatment options for breast cancer depend on various factors, including the stage of cancer, the type of breast cancer, hormone receptor status, and individual factors. Treatment may involve surgery (such as lumpectomy or mastectomy), radiation therapy, chemotherapy, targeted therapy, and hormone therapy. A combination of these therapies may be suggested in some circumstances.

What Is the Genetics of Breast Cancer?

Breast cancer can have a genetic component, meaning that certain inherited gene mutations can increase the risk of developing the disease. The two most well-known genes associated with an increased risk of breast cancer are BRCA1 (Breast Cancer gene 1) and BRCA2 (Breast Cancer gene 2). Mutations in these genes significantly raise the risk of developing both breast and ovarian cancers. Inheriting a mutated BRCA1 or BRCA2 gene does not guarantee that an individual will develop breast cancer, but it does increase the likelihood. These mutations are more commonly found in households having a background of ovarian or breast cancer. It's important to note that the majority of breast cancers are not caused by inherited genetic mutations but occur due to a combination of genetic and environmental factors.

Other genetic mutations, such as TP53 (associated with Li-Fraumeni syndrome) and PTEN (associated with Cowden syndrome), are also linked to an increased risk of breast cancer, although these mutations are relatively rare. If a person has a family history of breast or ovarian cancer, especially if multiple relatives were affected at an early age, they may consider genetic testing to assess their risk. Genetic testing can identify mutations in BRCA1, BRCA2, and other genes associated with breast cancer. The results of genetic testing can help individuals make informed decisions about their healthcare, including preventive measures and screening options.

What Are Breast Cancer Gene 1 And Breast Cancer Gene 2?

BRCA1 (Breast Cancer gene 1) and BRCA2 (Breast Cancer gene 2) are two well-known genes that play a crucial role in the development of breast and ovarian cancers. The mutations in these genes dramatically raise the risk of developing these types of cancers.

  • BRCA1: The BRCA1 gene produces a protein that aids in preventing the growth of tumors and repairing damaged DNA (deoxyribonucleic acid). Mutations in the BRCA1 gene can disrupt this normal function, increasing the risk of breast and ovarian cancers. A BRCA1 mutation increases a woman's lifetime risk of up to 70-80 % for breast cancer and up to 40-60 % for ovarian cancer. BRCA1 and BRCA2 gene mutations are typically autosomal dominant inheritance patterns, which means that a person who inherits a mutation from one parent has an increased risk of developing cancer. Men with BRCA1 or BRCA2 mutations also had a higher chance of getting breast cancer, even though the risk is lower compared to women.

  • BRCA2: The BRCA2 gene also produces a protein involved in DNA repair and tumor suppression. Mutations in the BRCA2 gene can result in an increased risk of ovarian and breast cancer. Having a BRCA2 mutation increases a woman's lifetime risk of up to 70 % for breast cancer and up to 10-30 % for ovarian cancer. Furthermore, BRCA1 and BRCA2 mutations are linked to an increased risk of other cancers, such as male breast cancer, pancreatic cancer, and prostate cancer.

Genetic testing can be conducted to identify BRCA1 and BRCA2 mutations. It involves a blood or saliva sample and is typically recommended for individuals with a family history of breast or ovarian cancer or those who meet specific criteria based on national guidelines. Individuals with BRCA1 or BRCA2 mutations may consider risk-reducing strategies, such as increased surveillance with regular mammograms, breast MRIs (magnetic resource imaging), and clinical breast exams, as well as options like preventive mastectomy or removal of the ovaries and fallopian tubes.


Breast cancer awareness, regular screenings, and early detection play a crucial role in improving outcomes. It is important to consult with healthcare professionals for proper evaluation, diagnosis, and personalized treatment recommendations for breast cancer. It is important to consult with a healthcare professional or a genetic counselor for comprehensive information, risk assessment, and guidance related to BRCA1 and BRCA2 mutations and their implications.

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Dr. Rajesh Gulati
Dr. Rajesh Gulati

Family Physician


breast cancer
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