Although the Lynch syndrome tumor spectrum is thought to be limited to cancers of the colorectum, endometrium, ovaries, stomach, and a few other cancer types, a recent article suggested there might be a broader tumor spectrum than previously considered. Furthermore, colorectal and endometrial cancers which develop among Lynch syndrome patients frequently are determined on tumor testing to have high microsatellite instability (MSI-H) or mismatch repair deficiency (MMR-D). The recently published study tested tumors in over 15,000 cancer patients with over 50 cancer types and found that among patients identified to have Lynch syndrome (based on germline DNA testing), 50% had tumors at sites other than the colorectum or endometrium, including urothelial, prostate, pancreas, adrenocortical, small bowel, sarcoma, mesothelioma, melanoma, gastric, and germ cell tumors. The investigators concluded that MSI-H/MMR-D predicts the presence of Lynch syndrome across a much broader tumor spectrum than currently appreciated and suggested that any patient with this tumor characteristic should receive a germline genetic assessment for Lynch syndrome regardless of cancer type or family history. This is particularly important given that Lynch syndrome tumors often respond to a new class of drugs (immunotherapy); thus, this information may help to guide cancer treatments.
Latham A, et al. J Clin Oncol. 2018 Oct 30. PMID: 30376427.