OncologyDr. Shrinidhi NathanyCancer Genomics

Consultant, Molecular Haematology & Oncology, Fortis Memorial Research Institute, Gurugram

Part 4 of 9 in Genomics Revolution in Cancer

Hereditary Cancer Risk: BRCA, HBOC Syndrome and the Case for Family Testing

January 19, 2025

A Risk That Is Underdiagnosed

Roughly 30 percent of cancers have a genetic basis, a share Dr. Nathany describes as underrated and underdiagnosed. Testing is the only way to identify which patients, and which families, fall into that group before a cancer develops or recurs.

Actress Angelina Jolie's inherited BRCA mutation, a breast cancer gene, led her to undergo a prophylactic mastectomy before cancer ever developed. Actress Hina Khan, diagnosed with breast cancer at an early stage, is undergoing genetic testing of her own. Both cases illustrate the same principle: knowing that a hereditary mutation exists, whether discovered before or after a diagnosis, changes what a patient and their family can do about it.

Hereditary Breast and Ovarian Cancer Syndrome

Breast cancer is the most commonly tested-for hereditary cancer today, largely because of hereditary breast and ovarian cancer syndrome. Dr. Nathany was clear, however, that many other cancers can also be inherited, and that testing should not be limited to breast and ovarian cases simply because that is where testing volumes are currently highest.

Why Family Testing Matters After One Diagnosis

When one member of a family develops cancer, testing that patient's genes can establish whether relatives carry the same inherited risk, so those relatives can be screened and, if a cancer does eventually develop, caught before it reaches a late, harder-to-treat stage. Genomic modification to prevent cancer outright is not yet possible; the realistic value of this information today is earlier detection in relatives already known to be at risk.

This guide is based on a live Jivo Masterclass: Dr. Shrinidhi Nathany taught doctors across Africa on January 19, 2025.

FROM THE LIVE Q&A

MO

Moderator

Can you clarify what CRISPR-Cas9 is?

SN

Dr. Shrinidhi Nathany

CRISPR-Cas9 is a technology related to gene therapy that lets you edit the gene. CRISPR is gene editing, and the Cas9 technology is what lets us edit the gene, for example the gene causing type 1 diabetes mellitus, and deliver it back to the patient so the disease is cured. That is not yet available in all countries.

See all 18 questions from this masterclass →

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Frequently Asked Questions

What is the most common genetic cancer?

The most common genetic cancer, as it's the most commonly tested for, is breast cancer. Breast and ovarian cancer has a syndrome called hereditary breast and ovarian cancer syndrome, and that is the most common because it is right now the most tested for. However, there are many more cancers which can be inherited.

Can molecular genomics help in preventing aging?

That is the most in-thing right now, which is longevity testing, which can tell you your actual biological age. Supposing you are 30 years of age by your date of birth, but because of stress your body may actually be 40 years old biologically. You can prevent that: we can first study why your body is aging faster, and then you can modify your lifestyle based on the genetics, what you should eat and what you should not eat and what kind of therapy you should take, and it gives you a lot of a personalised report.

Can you clarify more about gene therapy?

For example, sickle cell anaemia is caused by a point mutation where only one letter in the genome is changing. So what we can do is if A is becoming B, we make the B back to A and edit that gene, and deliver it through an IV cannula in the form of a solution. That is what is going to get integrated into the patient, and the disease can be cured. That is what gene therapy is.

Can we do genomic modifications to prevent cancer?

Well, not yet. What we can do is, supposing somebody in my family got cancer, I can get my genes tested so I know whether I am at risk of getting that cancer, and then I can try to catch it early, because once you're at a last stage it becomes difficult to cure. If you catch it early you can still cure the cancer.

What are the common tumour marker genes tested for routinely?

The recommendation is to test at least 50 genes. If somebody is interested I can send the list across to the Jivo team and they can share it with everybody.

What percentage of cancers have a genetic basis?

About 30 percent, according to Dr. Nathany, a share she describes as underrated and underdiagnosed.

What is hereditary breast and ovarian cancer syndrome?

An inherited genetic syndrome, including BRCA mutations, that raises the risk of breast and ovarian cancer and is the most commonly tested-for hereditary cancer syndrome today.

Can genomic testing prevent cancer from developing?

Not yet. What it can do is identify family members at inherited risk so they can be screened and, if cancer does develop, caught earlier.

Why should family members of a cancer patient consider genetic testing?

Testing the patient's genes can reveal whether relatives carry the same inherited mutation, allowing those relatives to be screened proactively rather than waiting for symptoms.

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