Smoking Increases Death Risk in Colorectal Cancer Survivors

Death risk twice as high for survivors who smoke compared with non-smokers.

Smoking was found to significantly increase the risk of death in colorectal cancer survivors in a recent study.

The study, published recently online in the Journal of Clinical Oncology, found that survivors of colorectal cancer survivors who smoke cigarettes face more than twice the risk of death than non-smoking survivors. The findings add to prior evidence that found a link between cigarette smoking and higher all-cause and colorectal cancer-specific mortality.

The study, conducted by the American Cancer Society, is one of the largest to examine smoking and colorectal cancer survival, and is also the first to prospectively collect statistics for pre- and post-diagnosis smoking.

While smoking has previously been associated with an increased chance of being diagnosed with colorectal cancer, the association with decreased survival following diagnosis with colorectal cancer was unclear.

The study sought to evaluate the link between smoking prior to and following diagnosis, with all-cause and colorectal cancer-specific mortality among survivors of the disease. The analysis included 2548 patients newly diagnosed with invasive, non-metastatic colorectal cancer from 184,000 adults in the American Cancer Society’s Cancer Prevention Study II.

Of the 2548 colorectal cancer survivors, 1074 of the patients died within an average of 7.5 years of follow-up time, including 453 patients who died from colorectal cancer. The study revealed that patients who smoked prior to diagnosis face more than twice the risk of death from all causes, in addition to the risk of dying from colorectal cancer.

Smoking before diagnosis was also associated with higher all-cause mortality, but was not associated with colorectal cancer-specific mortality. Smoking after diagnosis was found to more than double the risk of overall mortality over the duration of the study.

Smoking was also associated with approximately twice the risk of colorectal cancer-specific mortality. Additionally, the researchers found it to be plausible that smokers carry pathologically more-aggressive tumors and smoking may reduce the efficacy of colorectal cancer treatment.

"Further research is needed to understand mechanisms whereby smoking may increase colorectal cancer-specific mortality and determine if quitting smoking after diagnosis lowers the risk of colorectal cancer-specific mortality," the study authors wrote.