Four-year Genetic Registry data from 780 patients shows close to one in five tested positive for inherited cancer mutations; HBOC and Lynch syndrome together account for 90% of hereditary cases identified, prompting hospital to call for wider genetic screening
Mumbai: Nearly one in six patients tested for hereditary gastrointestinal cancer mutations at Kokilaben Dhirubhai Ambani Hospital, Mumbai, carries Lynch syndrome — a hereditary condition linked to colorectal and endometrial cancers. International literature has long estimated that Lynch syndrome accounts for roughly 5-8% of colorectal cancer cases worldwide. New four-year data from the hospital’s Genetic Registry puts the figure at 15.5% among patients tested at KDAH — almost three times higher, a finding doctors say could point to a hereditary cancer risk that is significantly under-recognised and under-screened among Indian patients more broadly.
The findings emerge from 780 cancer patients screened for inherited mutations at the hospital’s Hereditary Cancer Clinic over four years. Of these, 284 patients were tested for gastrointestinal cancer-linked mutations, and 44 — 15.5% — tested positive. Separately, 495 patients were tested for Hereditary Breast and Ovarian Cancer (HBOC) mutations linked to the BRCA1 and BRCA2 genes, of whom 103, or nearly 21%, tested positive. Taken together, close to one in five patients screened across both cohorts carried a pathogenic inherited mutation.
| HBOC | GI-Related | Total | |
| Patients Screened | 495 | 284 | 779 |
| Positive | 103 (20.8%) | 44 (15.5%) | 147 (18.9%) |
| Negative | 282 | 113 | 395 |
| VUS* | 110 | 127 | 237 |
*VUS: Variant of Uncertain Significance
The data comes from the hospital’s Genetic Registry, developed under its Empowering Families by Genetic Testing (EFGT) initiative and integrated with the secure REDCap data platform, linking genetic findings with clinical history and treatment outcomes. A key insight so far: HBOC and Lynch syndrome together account for nearly 90% of all hereditary cases tested and recorded, including both positive and negative results — making them, by a wide margin, the two most significant hereditary cancer syndromes affecting patients evaluated at the hospital.
Dr. Amrit Kaur Kaler, Consultant, Molecular Pathology, Kokilaben Dhirubhai Ambani Hospital, Mumbai, said, “Lynch syndrome is one of the most significant, and most overlooked, genetic drivers of hereditary cancer we are seeing in Indian patients. Our data shows that nearly one in six of our gastrointestinal cancer patients carry this mutation — a rate close to three times what is reported internationally. That is not just a statistic. It means that for every patient we identify, there are parents, siblings and children who could be silently carrying the same risk, unaware and unscreened. A genetic registry allows us to move beyond looking at cancer as an isolated disease in one individual. When we combine genetic information with family history, treatment and outcomes, we begin to see patterns that have implications for an entire family. This reinforces why identifying patients who may benefit from genetic evaluation, and building awareness around it, must become a healthcare priority.”
Dr. Manoj Mulchandani, Consultant, General Laparoscopic and Robotic Colorectal Surgeon, Kokilaben Dhirubhai Ambani Hospital, Mumbai, added, “Any new diagnosis of GI cancer below 50 or any family with a family member with cancer diagnosis below 50 years should undergo Genetic testing.”
The registry also supports precision oncology treatment data. Tumour, or somatic, testing examines genetic changes within a cancer itself, helping oncologists determine which combination of targeted therapy, immunotherapy or chemotherapy is likely to work best for a specific patient. Germline testing, by contrast, looks at the DNA a person was born with, flagging inherited mutations that may raise cancer risk for the patient and their biological relatives alike. Unlike routine blood tests repeated periodically, a germline test is typically done only once in a lifetime — the result does not change with age or lifestyle, and can inform risk assessment for an entire family.
In colorectal and endometrial cancers, microsatellite instability (MSI) testing often flags Lynch syndrome first, with germline testing used to confirm a hereditary basis. Testing is not offered indiscriminately — it follows clinical guidelines based on strong family history, younger age at diagnosis, and advanced or metastatic disease.
The registry has already surfaced rare cases: in one family with early-onset colorectal cancer — including a brother who died of the disease at 32 — testing identified a rare POLE associated polyposis-linked mutation in a surviving sibling, believed to be among the first such cases reported in India. The patient was placed under close surveillance, while another family member tested negative.
Clinicians say wider awareness is also needed to counter stigma around hereditary cancer, including the misconception that mutations pass through one parent alone. BRCA1/2 mutations are inherited equally from either parent — a father carrying the gene can pass it to his children, in whom it may surface as prostate or gastrointestinal cancer, just as it can as breast or ovarian cancer through the maternal line.
As the registry grows, KDAH aims to build a larger, longitudinal evidence base on how hereditary mutations present in Indian families and how patients respond to treatment — supporting earlier surveillance, more targeted genetic evaluation, and more personalised cancer care.
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