Smoking Linked to Higher Risk of Death among Colorectal Cancer Survivors

Colorectal cancer survivors who smoke cigarettes were found to face more than twice the risk of death than non-smoking survivors, corroborating existing evidence that cigarette smoking is associated with colorectal cancer-specific mortality.

Published online in the Journal of Clinical Oncology, the findings come from a new study by American Cancer Society researchers and their collection of both pre- and post- diagnosis smoking information.

To examine the association of smoking with all-cause and colorectal cancer-specific mortality among colorectal cancer survivors, lead author Peter Campbell, MD, and colleagues identified 2,548 people newly diagnosed with invasive, non-metastatic colorectal cancer from a total of 184,000 adults in the American Cancer Society's Cancer Prevention Study II. Among the 2,548 colorectal cancer survivors, it was reported that 1,074 died during the follow-up time — 453 deaths directly resulted from colorectal cancer.

The researchers noted that those who continuously smoked prior to diagnosis had more than twice the risk of death from all causes as well as from risk of dying of colorectal cancer. Former smoking before diagnosis was associated with higher all-cause mortality, but not with colorectal cancer-specific mortality. Smoking after diagnosis was also associated with more than double the risk of overall mortality throughout the study, and was associated with nearly twice the risk of colorectal cancer-specific mortality.

Existing evidence links smoking with higher chances of being diagnosed with colorectal cancer, but its association with survival after colorectal cancer diagnosis is unclear.

The authors mused plausibility that smokers have pathologically more-aggressive tumors, or that smoking may decrease 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 researchers concluded.