Scientists at the ASCO 2018 meeting revealed that Lynch syndrome, previously linked primarily to colorectal and endometrial cancers, is now associated with several additional cancer types. This has led to new screening recommendations for at-risk families.
What is Lynch Syndrome?
This genetic condition involves mutations in five mismatch repair (MMR) genes, increasing the risk of certain cancers. It tends to run in families.
New Cancer Types Linked to Lynch Syndrome
A genetic analysis of about 15,000 tumor samples from 50 cancer types identified the presence of high microsatellite instability (MSI-H), a genetic marker associated with Lynch syndrome.
While colorectal and endometrial cancer patients in the US are routinely screened for MSI-H, the study found that 16% of patients with MSI-H tumors across various cancer types also had Lynch syndrome.
Results from the Study
- Almost 1,000 tumors showed high or moderate MSI levels.
- Only about 25% were colorectal or endometrial cancers.
- Nearly 50% of Lynch-positive patients had cancers not previously or rarely linked to the syndrome, including mesothelioma, sarcoma, adrenocortical cancer, melanoma, prostate, and ovarian germ cell cancer.
Memorial Sloan Kettering Cancer Center stated: “Our findings suggest that all patients with MSI-H tumours should be tested for Lynch syndrome, regardless of cancer type or personal history.”
MD Anderson Cancer Center added: “These are tumor types that we would never have referred for genetic counselling.”
Implications for Screening and Treatment
The presence of the MSI-H marker in patients with prostate, ovarian, gastrointestinal, urinary tract cancers, and sarcomas indicates a risk of Lynch syndrome. These patients should also be screened for colorectal and endometrial cancers.
This shift is supported by the FDA's approval of immunotherapy drugs like Keytruda for any MSI-H tumor, regardless of its origin. This has also led health insurers to cover genetic testing for MSI-H and Lynch syndrome, paving the way for more personalized and preventive cancer care.