(HealthDay News) – Patients with Lynch syndrome, an inherited disorder of cancer susceptibility caused by mutations in a mismatch repair (MMR) gene, face significantly increased risks of a variety of cancers, including breast and pancreatic cancer, according to a study published online February 13 in the Journal of Clinical Oncology.

Aung Ko Win, MBBS, MPH, from the University of Melbourne in Australia, and colleagues prospectively followed a cohort of 446 unaffected carriers of an MMR gene mutation (161 with MLH1; 222 with MSH2; 47 with MSH6; and 16 with PMS2) and 1,029 of their unaffected relatives who did not carry a mutation, with follow-up occurring every five years. Country-, age-, and sex-specific standardized incidence ratios (SIRs) of cancer for carriers and noncarriers were compared with the cancer risk of the general population.

The researchers found that, over a median of five years of follow-up, mutation carriers had a significantly increased risk of endometrial cancer (SIR, 30.62), colorectal cancer (SIR, 20.48), ovarian cancer (SIR, 18.81), renal cancer (SIR, 11.22), pancreatic cancer (SIR, 10.68), gastric cancer (SIR, 9.78), urinary bladder cancer (SIR, 9.51), and female breast cancer (SIR, 3.95). There was no evidence that noncarrier relatives had an elevated risk of any cancer.

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“Our prospective analysis provides unbiased estimates of cancer risks for MMR gene mutation carriers, including significantly increased risks of recognized Lynch syndrome-associated cancers (colorectal, endometrial, ovarian, renal, gastric, and urinary bladder) and of breast cancer and pancreatic cancer,” the authors write.

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