SMOKING INCREASES MORTALITY IN COLORECTAL CANCER

In a study reported in the Journal of Clinical Oncology, Yang et al found that current smoking was associated with increased colorectal cancer–specific and all-cause mortality among colorectal cancer patients in both the prediagnosis and postdiagnosis settings.

Study Details

The study involved data from 2,548 adults in the Cancer Prevention Study II Nutrition Cohort who were initially free of colorectal cancer and were diagnosed with invasive nonmetastatic disease between 1992 or 1993 and 2009. Cause of death was determined through 2010. Smoking was self-reported on a baseline questionnaire and updated in 1997 and every 2 years thereafter. Postdiagnosis smoking data were available for 2,256 patients (88.5%). Prediagnosis smoking was assessed an average of 2.3 years before diagnosis, and postdiagnosis smoking was assessed an average of 1.4 years after diagnosis.

Patients had a mean age of 65 years at baseline and 73 years at diagnosis. Compared with never-smokers, former or current smokers were more likely to be men, less educated, and to have ever consumed alcohol. Current smokers were more likely to be diagnosed with colorectal cancer at a younger age, were less physically active, and were leaner, and former smokers were more likely to have a history of myocardial infarction.  

Prediagnosis Smoking Status

Overall, among the 2,548 colorectal cancer survivors, 1,074 died during follow-up, including 453 due to colorectal cancer. In multivariate analysis, prediagnosis current smoking was associated with significantly higher all-cause mortality (relative risk [RR] = 2.12, 95% confidence interval [CI] = 1.65–2.74) and colorectal cancer–specific mortality (RR = 2.14, 95% CI = 1.50–3.07) vs never-smoker status. Prediagnosis former smoking was associated with higher all-cause mortality (RR = 1.18, 95% CI = 1.02–1.36) but not colorectal cancer–specific mortality (RR = 0.89, 95% CI = 0.72–1.10).

Postdiagnosis Smoking Status

Postdiagnosis current smoking was associated with significantly higher all-cause mortality (RR = 2.22, 95% CI = 1.58–3.13) and colorectal cancer–specific mortality (RR = 1.92, 95% CI = 1.15–3.21). Postdiagnosis former smoking was associated with higher all-cause mortality (RR = 1.21, 95% CI = 1.03–1.42) but not colorectal cancer–specific mortality (RR = 0.91, 95% CI = 0.71–1.18).

The investigators concluded: “This study adds to the existing evidence that cigarette smoking is associated with higher all-cause and colorectal cancer-specific mortality among persons with nonmetastatic colorectal cancer.”

Peter T. Campbell, PhD, of the American Cancer Society, is the corresponding author for the Journal of Clinical Oncology article.

The study was supported by the American Cancer Society. The study authors reported no potential conflicts of interest.