More Evidence of the Perils of Smoking for Colorectal Cancer Survivors

When survivors of colorectal cancer smoke, their risk of death more than doubles compared with their counterparts who do not smoke, a new study by researchers at the American Cancer Society has found. The research offers yet more evidence of the dangers of smoking in this setting and more data clinicians can use to drive that message home when counseling survivors.

The findings, published online in the Journal of Clinical Oncology, come from one of the largest studies of smoking and colorectal cancer (CRC) survival and the first to prospectively collect smoking information both before and after diagnosis. The researchers noted that although existing evidence supports a link between smoking and a higher risk of developing CRC, its association with survival is unclear.

For the study, survival and smoking status were analyzed for a subset of 2548 individuals diagnosed with invasive, nonmetastatic CRC who were part of the much larger American Cancer Society’s Cancer Prevention Study II (n = 184,000). After a median 7.5 years of follow-up, 1074 of the survivors in the CRC analysis had died, 453 of them from CRC.

Researchers found that those who smoked before diagnosis had more than twice the risk of death from all causes (relative risk [RR] = 2.12), as well as from dying from colorectal cancer specifically (RR = 2.14). Former smoking before diagnosis was associated with higher all-cause mortality (RR = 1.18) but not with colorectal cancer—specific mortality. Smoking after diagnosis was also associated with more than double the risk of overall mortality (RR = 2.22) over the course of the study and was associated with nearly twice the risk of colorectal cancer–specific mortality (RR = 1.92).

The authors noted that it is possible that smokers have more aggressive tumors, or that smoking may decrease the effectiveness 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.”

In the meantime, when oncology nurses and other practitioners have follow-up visits with CRC survivors, counseling them to not smoke should be a priority.

Zana Correa, NP, a nurse practitioner at Memorial Sloan Kettering Cancer Center’s Survivorship Center who has special training in colorectal cancer survivorship issues, noted that while some CRC patients stop smoking, unfortunately others restart.

“Most survivors have stopped by the time they see me, and most are very aware of the risks,” she said, not only of the perils of smoking but also the importance of other risk factors, such as alcohol use. She added that during clinic visits, she stresses all of the data that support smoking cessation and directs survivors to smoking cessation resources. “If they are still smoking, that is a big part of the appointment.”

Yang B, Jacobs EJ, Gapstur SM, Stevens V, Campbell PT. Active smoking and mortality among colorectal cancer survivors: The Cancer Prevention Study II Nutrition Cohort [published online February 2, 2014]. J Clin Oncol.