Is Breast Cancer Hereditary?

Breast cancer is a serious health concern that affects millions worldwide. One of the most pressing questions for those who have been diagnosed with breast cancer, or who have a family history of the disease, is whether or not it is hereditary. While the vast majority of breast cancer cases are not passed down, for those who have a family history of the disease, the risk of developing breast cancer may be higher. 

 

What Is Breast Cancer?

Breast cancer forms in the breast tissue and is one of the most common cancers worldwide. It occurs in both men and women, although it is much more common in women. 

Breast cancer can take many forms, but generally, when we speak of breast cancer we are referring to the most common type: invasive breast cancer. Specifically, invasive ductal carcinoma (IDC), which starts in the milk ducts and can spread to nearby tissues. 

Non-invasive breast cancer includes ductal carcinoma in situ (DCIS), the earliest form of breast cancer. Less common types of breast cancer include invasive lobular carcinoma (ILC) and inflammatory breast cancer. Metastatic, advanced, or secondary breast cancer is when it spreads to other parts of the body.

 

Can You Inherit Breast Cancer?

Various factors contribute to the development of breast cancer, including genetic and environmental influences. 

Only 5-10% of breast cancer cases are believed to be hereditary. The vast majority of breast cancer cases are sporadic, meaning they occur by chance and are not linked to an inherited genetic mutation. However, faulty genes (mutations) can be passed from parent to child, so for those who have a family history of breast cancer, the risk of developing the disease is higher than those who have not inherited these faulty genes.

Hereditary Breast Cancer

The most well-known genes associated with hereditary breast cancer are BRCA1 and BRCA2. These genes act as tumour suppressors, regulating cell division and preventing uncontrolled cell growth. Inherited mutations in these genes can lead to the loss of their tumour-suppressing function, increasing the risk of cancer.

Women and men who carry a harmful mutation in the BRCA1 or BRCA2 gene have a higher chance of developing several types of cancer, including breast, ovarian, pancreatic and prostate cancers (with breast cancer having the highest risk). More genes are being discovered that may influence the risk of breast cancer, such as TP53 and CHEK2. Speak to your doctor about the latest research and available genetic tests.  

 

How Is The Risk Of Hereditary Breast Cancer Determined?

Why some get breast cancer and others don’t is still not fully understood, but there are known factors that influence how likely you are to develop breast cancer. Factors that increase breast cancer risk include:

Age

The older you are the more gene mutations you can accumulate by pure chance, which can lead to cancer. Most breast cancers occur in women over the age of 50 who have already been through menopause, although younger women can also develop breast cancer.  

Family History

If your immediate family has a history of breast or ovarian cancer your risk is much higher, especially if they were under 50 or if multiple family members have a history of cancer. 

Personal History

If you have previously had breast cancer or have had a benign (non-cancerous) breast lump you may be at greater risk. Other factors that may affect your risk include whether you have undergone hormone replacement therapy (HRT) for over a year, are or have been on the contraceptive pill, are overweight, consume alcohol, or have received radiotherapy or x-rays/scans of the chest area.

There are many more factors your doctor may consider when assessing your risk, including Jewish ancestry, certain childhood cancers, breast cancer in male relatives, and more. The presence of any of these factors does not mean that you will get breast cancer, they merely increase your risk. Many people have family members who have had breast cancer yet do not develop it themselves, as most breast cancer does not run in the family. 

 

When Should I Consult A Doctor About Breast Concerns?

If you are concerned about your risk of developing breast cancer, speak to your doctor. The above factors will be considered (along with others). If you have a family history of breast, ovarian, prostate, or pancreatic cancer, you may benefit from hereditary risk evaluation to assess the risk of developing these cancers. This could include a referral for genetic testing.

Genetic testing plays an important role in identifying whether someone is at higher risk of hereditary breast cancer. It involves analysing specific genes to find out if you have mutations or variations associated with an increased chance of developing cancer, including variants or mutations in the BRCA1 and BRCA2 genes. 

The results can help to guide management decisions and risk reduction strategies. Genetic counselling is crucial before and after testing to provide comprehensive information and support.

Remember, most cancers occur via an accumulation of randomly acquired mutations, either as an error in normal cellular processes or due to the environment. If you have a family history of cancer, it does not mean that there is a hereditary component. And if you have inherited a genetic variant, it does not mean that you will develop cancer. It simply increases your chance of developing it.

 

What Can Be Done To Reduce The Risk Of Hereditary Breast Cancer?

For individuals identified as having a hereditary predisposition to breast cancer, proactive management and prevention strategies are available. This includes regular breast cancer screenings, such as mammograms and MRIs, starting at an earlier age and at shorter intervals. Prophylactic surgeries, such as bilateral mastectomy or oophorectomy, may be considered to reduce the risk. 

Lifestyle modifications, such as maintaining a healthy weight and avoiding excessive alcohol consumption, are important. Chemoprevention drugs, such as tamoxifen or raloxifene, may also be recommended in certain cases. 

The choice of risk reduction options should be made in consultation with a healthcare provider, taking into account individual risk factors and personal preferences.

 

Does Breast Cancer Run In The Family?

Breast cancer can be hereditary, meaning that you could inherit an increased risk of developing the disease. This risk comes in the form of an inherited mutation (genetic ‘error’) that could be passed down from either your mother or your father. While only a small portion of breast cancer cases have a hereditary cause, it is important to understand your risk.

Genetic testing, along with thorough risk assessment, can help identify those who have a higher risk of developing breast cancer. This allows for tailored management and prevention strategies and is an essential part of early detection, improving outcomes, and reducing the burden of this disease. If you have concerns about your risk of breast cancer, it is important to speak with a healthcare provider.