CHENNAI: As clichéd as it is, prevention is better than cure; especially when there is no cure. For centuries, our fight against cancer has resulted in the loss of millions of lives but despite this impact, many remain unaware of the basic aspects of this disease. Worldwide, approximately 10 per cent of breast cancer cases are inherited. Our BRCA 1 and BRCA 2 genes are vital for fighting cancer but unfortunately, lethal if mutated. If you inherit a variant of these genes from your parents, you too could be at the risk of developing cancer. Thankfully, there are now ways to recognise these genes before they manifest in your body.
This Breast Cancer Month, Dr Divya Agarwal, clinical advisor at LifeCell Labs introduces and elaborates on hereditary cancers and genetic screening.
Could you explain the science behind how someone could inherit breast cancer?
All cancers are genetic (all may not be hereditary) as they come with certain mutations in specific genes. We have a pair of each gene. To be able to disrupt the gene, usually, there is a mutation in both the copies and that’s how it makes the gene non-functional and predisposes the cells carrying the mutation to divide indefinitely. However, if some patients already have a damaged copy of a gene that is important in this cell cycle or repair of DNA, inherited from their parents, the patient would be at an increased risk of developing hereditary cancer. Ten per cent of the population has already carried or inherited the mutation from the parents.
Does the inherited mutation pose a greater threat? Could it skip generations?
The inherited mutation does pose a greater threat. Hereditary cancer behaves differently from the ones that appear sporadically. It manifests at an early stage, has more chances of relapse, is a little more aggressive and responds to certain groups of drugs and not others. The mutation carriers will also be at risk of developing cancers in other areas of the body, like ovarian cancer. Which in cases of sporadically developed, is less likely.
It could skip generations in the manifestation of cancer. A person might have inherited the mutation from their parent and that will be passed to their children, but for some reason, they might not show cancer. That way, the inheritance of the gene wouldn’t skip generations but the manifestation of cancer may appear through skipped generations.
What is genetic screening and what are the benefits of getting it done?
Genetic screening is the test or technology by which we are able to identify individuals who might be at risk of developing breast cancer. In it, we would test the blood sample of the patient and look for mutations or changes in one of the hereditary cancer genes, which would make them susceptible to cancer.
How does one know when or if they should test for it?
The answer to this has progressively changed over time. Earlier, we had very complicated algorithms to study individuals — if there is a family history of cancer, age, and other lifestyle factors like smoking, alcoholism, obesity. On basis of these risk factors, we would calculate a tentative probability of that patient developing breast cancer. If the probability is more than 10 per cent, you should get tested for BRCA 1 and 2 mutations. However, now studies prove that such probability modules seem to miss more than 40-50 per cent of individuals who may be harbouring these cancer susceptibility genes and genetic screening should be offered on a population basis so as to not miss any individual with these mutations. As of now, it is not really the recommended protocol. However, if a patient wants to know, they can get the test willingly.
What is the difference between genetic screening and a mammogram?
In genetic screening, we are picking up your susceptibility to getting cancer, while in a mammogram, we are picking up growth in the breast or breast cancer at an early stage. We wouldn’t find anything in a mammogram before it has already developed. Genetic screening is more of a preventive measure.
Genetic screening is a simple blood test or, in some labs, a buckle swab (cotton swab moved around in the mouth). After the blood sample, we process it for extracting DNA and then a machine analyses the gene. In LifeCell Labs, there is a hereditary breast-ovarian gene panel that tests BRCA 1, BRCA 2 and some other genes that seem to increase susceptibility. The data would come back in 2-3 weeks. There is also pre-test and post-test counselling that is a fundamental element of all international guidelines for a patient to make an informed decision. This includes a lot of explaining about how the results will return and what to do when they come. Even with negative results, if they have a family history, it is important for them to have post-test counselling with a clinician.
What happens after they test positive?
For BRCA 1 variants, there is a good risk that they might develop cancer at some age. The exact age cannot be predicted very accurately, but it can be prevented by lifestyle modifications; smoking, alcoholism, obesity increase the risk. A healthy lifestyle is recommended to everyone but it is absolutely important to those who have BRCA mutations. There would also be rigorous surveillance and the process of screenings will become more stringent and frequent. Alternatively, there is chemoprevention. Certain drugs can be given to totally prevent cancers and carriers may opt for certain surgeries to absolutely nullify the risk. They would also need counselling regarding the risk of passing on this mutation. Other family members (sisters, brothers) should get a test too.
Is there enough awareness about genetic testing and hereditary cancers in India?
There is a huge scope for improvement in the prevention of hereditary cancer and awareness of screening. There is a recent study (2020) that compares the mortality in India to the rest of the world in terms of cancer. The ratio of the number of deaths to new cases of breast cancers is about 57 per cent in India. The high mortality rate can be prevented by creating awareness, early screening, detection at an early stage for more targeted therapy. Worldwide, about 10-12 per cent of women will develop breast cancer. Now, genetic tests are becoming increasingly affordable and readily available. But, awareness is lacking. Seven to eight years back, it cost `20,000-`25,000. Now, it has been reduced to more than half. I would say less than `10,000. And it is just a one-time screening.
What are some misconceptions about hereditary cancer we need to bust?
One of the main misconceptions is that breast or ovarian cancer can only develop in people with a family history. You could be the first person manifesting hereditary cancer; there could be skipped generations. There needs to be proper awareness not only in the population but also clinicians and the medical community to do more targeted testing for hereditary breast cancer. Another misconception is that men cannot get breast cancer. That is not true, but there is a slightly lower risk of manifesting it. The gene, however, can be inherited by the father and passed on to the children hence creating skipped generations.