Smoking Linked to Colorectal Cancer in Patients With Lynch Syndrome

SALT LAKE CITY (October 28, 2019) – Cigarette smokers with Lynch syndrome stand a greater chance of having more than one colorectal cancer diagnosis in their lifetime, but are less likely to receive a cancer diagnosis before age 50, according to a new study.

The research will be presented at the 2019 Collaborative Group of the Americas (CGA) Annual Meeting by Beth Dudley, MS, MPH, a genetic counselor at the UPMC Hillman Cancer Center. The annual meeting is being held November 3-5, 2019, in Salt Lake City. Michael Hall, MD, MS, chair of the Department of Clinical Genetics at Fox Chase Cancer Center, is president of the CGA.

Lynch syndrome (LS) is a genetic condition that predisposes people to increased risk for colorectal and other types of cancer. It is caused by inherited mutations in genes called MLH1, MSH2, MSH6, PMS2, and EPCAM.

Research has shown that stopping smoking could decrease the risk of developing colorectal cancer in those with LS.

“Previous studies showed that smoking does increase risk for colon cancer in those with Lynch, but there’s very little data about how it affects age of diagnosis or number of cancer diagnoses,” said Dudley.

Dudley and her team analyzed 237 Lynch syndrome patients from their own registries who either smoked or never smoked.

Overall, smokers were more likely to develop more than one colorectal cancer, but surprisingly, nonsmokers who developed cancer were significantly younger than smokers when they received their first diagnosis. Smokers were about 52 years old at the time of first diagnosis. Nonsmokers were about 45 years old. What’s more, nonsmokers were more likely to be diagnosed with their first cancer before age 50 than smokers.

The researchers are unsure why nonsmokers in their registries were more likely to be diagnosed with cancer at younger ages than smokers, but Dudley emphasizes: “We aren’t telling people with Lynch syndrome that they should smoke. One possibility is that individuals with Lynch syndrome who are diagnosed with cancer at younger ages might have other hidden factors that increase their cancer risk, whereas lifestyle risk factors play a larger role for people who are diagnosed with cancer later in life. Ultimately, more research is needed to determine if these findings hold true in studies of larger groups of individuals with Lynch syndrome.  If they do, further research to identify the reason would be warranted.”