Colon Cancer Patients Who Smoke are at Higher Mortality Risk

February 2020

Mark McGraw,

A new analysis finds that patients being treated for colon cancer who also smoke are more likely to die within 5 years than colon cancer patients who
have never smoked.

With a growing body of evidence to suggest that smoking might adversely affect cancer patients’ outcomes, a team of researchers sought to investigate whether smoking status at diagnosis is an independent prognostic factor for cancer-specific survival in colon cancer, and whether treatment modifies
any impact of smoking.

To accomplish this goal, the investigators examined colon ademocarcinomas diagnosed between 1994 and 2012 from the National Cancer Registry Ireland, classifying patients by smoking status at the time of diagnosis. The authors compared cancer-specific death rates over 5 years in current, exand never smokers, using multivariable Cox proportional hazards models, and conducting subgroup analyses by treatment (combinations of cancer-directed surgery and chemotherapy).

Among the 18,166 colon cancer patients studied, 20% were current smokers, while 23% were ex-smokers, and 57% had never smoked. Compared to those in the group that had never smoked, current smokers had a significantly raised cancer death rate (14% greater than other groups), with a significant interaction between treatment and smoking. In those who had cancer-directed surgery only, current smokers were 21% more likely to die from their colon cancer compared to never smokers, according to the researchers.

While noting that “further research is needed elucidate mechanisms, continued efforts to encourage smoking prevention and cessation may yield benefits in terms of improved survival from colon cancer,” the authors wrote, adding that the limitation of the association to surgically-treated patients suggests that the underlying mechanism, or mechanisms, could be related to surgery. Moreover, the results of this research “suggest that people who smoke and are diagnosed with colon cancer should be encouraged and supported to stop smoking, as this might help ensure they have the best outcomes,” said Linda Sharp, PhD, a professor of cancer epidemiology at Newcastle University, and the study’s lead author. “So, for primary care practitioners, the message is clear—they should encourage these patients to engage with smoking cessation services and supports.”