According to the World Health Organization (WHO) and the American Cancer Society, cancer accounts for about 1 in 6 deaths worldwide - more than HIV/AIDS, tuberculosis, and malaria combined. The report states that by 2040, the global burden is expected to reach 27.5 million new cancer cases and 16.2 million cancer deaths. A WHO estimate in 2018 projected that 1 in 10 Indians will develop cancer during their lifetime and 1in 15 will die of the disease.

About 5-10% of all cancers are hereditary and occur due to inheritance of a genetic variation/mutation within families, especially in close family members. Examples of such hereditary cancer syndromes, also called familial cancer syndromes, are hereditary breast and ovarian cancer syndrome, Li-Fraumeni syndrome, Cowden syndrome, and Lynch syndrome.

Unlike localized (somatic) genetic variations that are acquired over the course of one's life, inherited or familial variations are transmitted from one generation to another and can thus predict the increased lifetime risk of developing cancer. The presence of such variations can also indicate the early onset of the disease.

From a comprehensive cancer treatment point of view, the knowledge of hereditary gene mutations has a plethora of applications including better disease management and application of preventive strategies such as risk-reducing surgeries, which can improve survival. Asymptomatic carriers can also be benefitted from chemoprevention and enhanced surveillance approaches.

There are about 100 genes that are associated with hereditary cancer development and information about mutations in these genes can be used to tailor prevention, surveillance, and treatment of cancer. Genetic testing to detect such inherited variations helps an Oncologist in making a well-informed treatment decision.

Hereditary cancers are known to have a poor-prognosis- meaning these cancers are comparatively more aggressive. This information can aid in better clinical management decisions. Further, mutations in certain genes increase response to drugs and thus contribute to precision/personalized medicine wherein patients are treated based on the mutations identified in them.

For example, women diagnosed with HBOC (Hereditary Breast and Ovarian Cancer syndrome), with a mutation in the BRCA1/2 gene, respond to targeted treatment using Poly ADP-ribose polymerase (PARP) inhibitors.

Considering the multiple advantages of identifying genetic variations in hereditary cancers, the health care fraternity globally, has been trying to make genetic testing more affordable and widely available to the public, enabling easier diagnosis, management, and treatment of this disease.

Sequencing of multiple cancer susceptibility genes simultaneously has now become available through multi-gene panel testing in a rapid and cost-effective manner. This is a breakthrough that will result in a new era of personalized healthcare for hereditary cancers in the decades to come.

-Article by Dr. Lakshmi Mahadevan, Principal Scientist, MedGenome Labs Ltd

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What genes tell us about the risk of developing cancer - India Today

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