How Screening for Lynch Syndrome Affects Colon Cancer Risk

While colorectal cancer is the 3rd most common cancer in both men and women, incidence rates have decreased over the past 2 decades. Consequently, mortality rates from colorectal cancer have also declined in men and women, reflecting this and improvements in early detection and treatment. Early detection is made possible through screening and colonoscopy.

Our data show that if people aged 50 and older were screened regularly, we could prevent 6 of 10 deaths from colorectal cancer. Multiple efforts are underway, both nationally and locally, to expand colorectal screening to younger people who may be at higher risk. This includes those with a known history of colon cancer and those with known hereditary familial syndromes, like Lynch syndrome.

What is Lynch syndrome?

Lynch syndrome is a genetically inherited disorder that increases the risk of colorectal and endometrial cancers and several other malignancies. In the U.S., an estimated 1 million people live with Lynch syndrome. Lynch syndrome was described in the medical literature in the 1950s, and much of the genetic etiology was uncovered in the early 1990s. Still, many patients remain undiagnosed or have a significant delay in diagnosis. This can critically impact affected patients and their family members.

Detecting and treating Lynch syndrome

One way to identify people with Lynch syndrome is to obtain a family history for cancer and then apply risk-prediction models, like Bethesda and Amsterdam II criteria. If the patient meets the clinical criteria, then we can test for DNA abnormalities related to colorectal and endometrial cancers. If abnormalities exist, we can perform definitive germline genetic testing and offer counseling to determine whether an individual has Lynch syndrome.

If the patient is diagnosed with Lynch syndrome, he/she is at risk for developing other Lynch-related cancers. Family members must undergo genetic counseling and germline testing for the disease as well. Lynch syndrome is associated with an autosomal dominant pattern of inheritance and is likely to clinically manifest in those with the abnormal gene. Family members diagnosed with Lynch syndrome are at risk of developing Lynch-related cancers in the future.

Timely identification of Lynch syndrome is critical. Not only does it allow for cancer screening at an earlier age, it also has the potential to improve patient outcomes. In addition to subspecialized gastrointestinal oncology clinics, we also have a high-risk gastrointestinal clinic for patients with a family history of colon cancer or Lynch syndrome. This clinic focuses on primary prevention methods like screening colonoscopy, formulating surveillance plans and referrals for surgical intervention, if needed.

Caring for colon cancer patients and their families provides us with tremendous insight and perspective. Their daily battles are heart-wrenching and motivate clinical researchers like us to continue our efforts fighting this life-threatening and potentially preventable malignancy. It is an honor and a privilege to care for our patients and make a difference in their lives using standard-of-care treatments, investigational therapeutics or chemoprevention approaches.