1 in 4 Indian breast cancer patients carry inherited genetic risk variants, outside known genes: study

A study reveals 1 in 4 Indian breast cancer patients carry inherited genetic variants beyond known BRCA genes, urging broader testing strategies.

One in four Indian breast cancer patients carries an inherited genetic variant linked to cancer risk, with the majority of these variants occurring outside the well-known BRCA1 and BRCA2 genes, a new study has found, a press release said.

Findings of the study, conducted by the Indian Institute of Technology-Madras (IIT-M) and Karkinos Healthcare, along with Kumaran Hospital, Chennai, and the Chennai Breast Centre, were published in the journal BMC Cancer

The study analysed germline DNA from 479 unselected breast cancer patients, whose samples were sourced from the National Cancer Tissue Biobank at IIT-Madras. The researchers examined 97 cancer susceptibility genes, including BRCA1, BRCA2, and 15 genes involved in the homologous recombination repair pathway. Variants were classified using internationally accepted ACMG/AMP guidelines. A special focus was placed on RECQL, an emerging breast cancer gene with highly population-specific patterns.

Read the full study here.

The study found that 24.6% of patients carried at least one pathogenic or likely pathogenic variant. Only 8.35% had BRCA1 or BRCA2 variants, while a significantly larger proportion, 11.9%, had inherited pathogenic variants in genes belonging to the homologous recombination repair pathway. Overall, 67% of all positive findings occurred in non-BRCA genes, including MLH1, NF1, TP53, and RB1, demonstrating that the inherited landscape of breast cancer risk in India is far more complex than previously appreciated.

The findings underscore the need to re-examine current genetic testing strategies in India, which continue to rely heavily on BRCA-only, and to shift to broader multi-gene panel or exome-based germline testing. The research team noted that expanding such studies nationally could help develop genomic policies tailored to India’s unique population structure and disease burden.