NLCAHR

Study Background: Smoking is a risk factor for incident colorectal cancer (CRC); however, it is unclear about its influence on survival after CRC diagnosis.Methods: A cohort of 706 CRC patients diagnosed from 1999 to 2003 in Newfoundland and Labrador, Canada, was followed formortality and recurrence until April 2010. Smoking and other relevant data were collected by questionnaire after cancer diagnosis,using a referent period of ‘2 years before diagnosis’ to capture pre-diagnosis information. Molecular analyses of microsatelliteinstability (MSI) status and BRAF V600E mutation status were performed in tumour tissue using standard techniques. Multivariatehazard ratios (HRs) and 95% confidence intervals (CIs) were calculated with Cox proportional hazards regression, controlling formajor prognostic factors.

Results: Compared with never smokers, all-cause mortality (overall survival, OS) was higher for current (HR: 1.78; 95% CI: 1.04–3.06),but not for former (HR: 1.06; 95% CI: 0.71–1.59) smokers. The associations of cigarette smoking with the study outcomes were higher among patients with X40 pack-years of smoking (OS: HR: 1.72; 95% CI: 1.03–2.85; disease-free survival (DFS: HR: 1.99; 95%CI: 1.25–3.19), those who smoked X30 cigarettes per day (DFS: HR: 1.80; 95% CI: 1.22–2.67), and those with microsatellitestable (MSS) or MSI-low tumours (OS: HR: 1.38; 95% CI: 1.04–1.82 and DFS: HR: 1.32; 95% CI: 1.01–1.72).  Read more here: http://www.nlcahr.mun.ca/Funding/BJC_Paper_Yun_Zhu.pdf