ABSTRACT: Lynch syndrome, previously known as hereditary nonpolyposis colorectal cancer, is an autosomal dominant inherited cancer susceptibility syndrome caused by defects in the mismatch repair system. This system depends on a family of genes that are conserved across most living organisms and is responsible for repairing single-base mismatches that occur during DNA replication. In addition to colorectal cancer, hallmark diseases of Lynch syndrome include endometrial and ovarian cancer. Other tumors within the spectrum of Lynch syndrome include gastric cancer, small bowel cancer, hepatobiliary cancer, renal pelvis and ureter cancer, as well as some types of breast cancer, certain brain tumors, and sebaceous skin tumors 1 2 3 4. By identifying individuals at risk of Lynch syndrome through assessment of personal and family medical histories and genetic counseling and testing, when indicated, physicians are able to offer screening and prevention strategies to reduce morbidity and mortality from this syndrome.

Notably, the molecular abnormalities present in Lynch syndrome-associated tumors cause specific changes in the tumor tissue that can be detected by laboratory testing and, thus, identify the syndrome even in the absence of an informative family medical history. Because two of the most common types of cancer in Lynch syndrome occur in the female reproductive tract, obstetricians, gynecologists, and gynecologic oncologists are in a unique position to identify women who are at substantial risk of Lynch syndrome. The purpose of this document is to educate and provide an overview of Lynch syndrome because early identification of mutation carriers allows prevention of most Lynch syndrome-associated malignancies 5 6.