The Inheritance Of Breast Cancer & Why Genetic Testing Is Critical

It was Angelina Jolie who famously paved the way for cancer prevention when she opted for her double mastectomy. This decision was based entirely on family history. After her mother died of ovarian cancer, Jolie screened herself for genetic risk factors and found herself positive. Since then, she’s been vocal about the importance of genetic testing in women who are considered high-risk. As we celebrate Breast Cancer Awareness Month this October, let’s take a look at why genetic testing for breast cancer matters now even more than before.

India records roughly around two lakh breast cancer cases every year, and the number is just growing. Women in their 20s and 30s are increasingly at risk, and part of the problem here is a genetic correlation. Around five to 10 per cent of breast cancer cases are ‘inherited’ from the family’s risk factors.

“Breast cancer is the largest killer among women worldwide and in India, with the highest prevalence being in Kerala, Andhra Pradesh and Telangana,” says Dr Pratibha Singhal, a gynaecologist at Cloud 9 Hospitals in Noida. “Overall, there are 200 cases of breast cancer per one lac women,” she adds.

Inheriting breast cancer: The parameters you should know

As far as genetic correlation goes, she says, “Anyone with a strong family history of breast or ovarian cancer – that is in two or more close female relatives – is at risk. Also, if a girl has Jewish origin or European ancestry, she is found to be more susceptible to genetic cancer. If someone has already suffered from cancers related to the ovary or breast on one side, there could be a genetic correlation to have an early diagnosis for the other side.”

Dr Priya Selvaraj, gynaecologist and fertility specialist at GG Hospitals, Chennai, “Earlier it was cancer of the cervix that was the number one in India for women, but today, it is breast cancer. Just as genetic contribution to breast cancer is about five-10 per cent, its contribution to ovarian cancer is about 10-12 per cent. I’ve had two cases of women who were 23 and 25, coming to me with breast cancer that was later found to be genetically passed on. The testing helps decide the treatment and mapping of family history, who should be tested, and to find out if this is going to be of significance to them.”

The two main tests for breast cancer are called BRCA1 and BRCA2 - pronounced brak-uh, rather than by their abbreviations! They are simple blood tests (although some advanced clinics are now advocating simpler saliva tests) that stand very simply for ‘BReast CAncer’. Since there are two different genes discovered in the early 1990s, they have been named - rather unimaginatively - 1 and 2.

How does one decide whether they need to get tested for BRCA1 and BRCA2? Says Dr Singhal, “Generally, a girl can visit a breast oncologist for counselling, who refers her to screening for these tests if she is considered to be at risk. The tests are expensive, but if there is a genetic correlation, it is also very important to do them.

Finding Out You Are Positive: The Next Steps

Now, if a girl finds out that she's positive, what do we do? If she's not already suffering from breast cancer, we recommend regular self-examinations and screenings so as to diagnose cancer in its very early stages. This way, management is easy and the long-run prognosis is good. If she already has breast cancer, the oncologist will determine how her line of treatment will change, based on her BRCA1 or BRCA2 status.”

It is interesting to note that every single human being comes with the BRCA genes, and they actually promote breast health and prevent breast cancer when they work properly. However, when the gene doesn’t do its job well or is broken, that mutation could be passed on to other women in the family. That is when one tends to find themselves testing positive for BRCA 1 or 2.

Remember though, these tests are just indicative of whether you have a genetic predisposition to cancer. If you test positive, it doesn’t mean that you will get it for sure (although, there is a very strong probability – nearly 50 per cent!). Similarly, if you test negative, it doesn’t mean that you will never get breast cancer – there are many other factors that could potentially contribute to its occurrence. Birth control, childbirth, breastfeeding patterns and menstrual history are just some of the other factors in women below 40.

When growth or incidence of a tumour is found, it can be quite scary. But early action is of utmost importance. Dr Selvaraj says, “First, a FNAC fine needle aspiration cytology or an excision biopsy is conducted. Cells and tissues are read, and you get a diagnosis of what kind of breast cancer it is. This determines treatment regimes and prognosis.”

If they’ve got the BRCA gene mutation, women as young as 20 or even 18 can develop breast cancer. So, it is absolutely worthwhile doing regular check-ups and staying one step ahead of the disease by being prepared for its occurrence. Doing this may not just help you, but also save lives and help other women in your family from being ignorant of their risk factors.

Staying One Step Ahead Of Breast Cancer

While Angelina Jolie chose to pre-empt breast cancer with her mastectomies, Christina Applegate wasn’t as lucky. She learnt she had the BRCA 1 genetic mutation only after she was diagnosed with breast cancer at the age of 36. This was over 14 years ago.

Says Dr Singhal, “Even if those at high risk don’t want to test for BRCA 1 or 2, they should be counselled for regular check-ups. Ultrasounds and self-examinations are recommended, and for women over 40, annual mammography is. In younger women, the mammography may not reveal much because of breast density.”

She rues that genetic cancers cannot be prevented no matter how much you screen, but awareness is key to tackling preventive healthcare and early detection. Also, cancer treatments are constantly evolving. “Even though the number of instances of breast cancer have increased, the mortality rates have decreased, thanks to advances in medicine.” That’s the silver lining we’re all looking for!