Combined associations of a healthy lifestyle and body mass index on colorectal cancer recurrence and survival: A cohort study.

Abstract

3609 Background: Colorectal cancer (CRC) risk is associated with modifiable lifestyle factors including smoking, physical inactivity, Western diet, and excess body weight. The impact of lifestyle factors on survival is less known. A cohort study was conducted to investigate the combined effects of a pre-diagnostic healthy lifestyle and body mass index (BMI) on prognosis following CRC diagnosis. Methods: Treatment and follow-up data were collected from the patient files of 1098 participants from the Swedish Colorectal cancer low-risk study cohort including stage I-III CRC patients. A healthy lifestyle and BMI (HL) score was computed using self-reported data on smoking status, physical activity, adherence to a Mediterranean diet pattern, and BMI five years before diagnosis, and divided into four categories ranging from least to most healthy. Survival analyses were performed to assess recurrence-free survival and overall survival across categories of exposure, using the Kaplan-Meier method and Cox proportional hazards model, the latter adjusted for age, sex, and educational level. Results: Among 1098 participants with stage I-III CRC, 233 (21.2%) had an HL score of 0-1 (least healthy), 354 (32.2%) HL score of 2, 357 (32.5%) HL score of 3 and 154 (14.0) HL score of 4 (most healthy). Participants missing follow-up data (n = 29) or relapsing ≤ 6 months (n = 29) were excluded from the recurrence-free survival analysis. 221 events of cancer recurrence were observed among 1040 participants during a median follow-up time of 4.3 years, and 542 deaths among 1098 participants during a median follow-up time of 6.3 years. Patients with the healthiest lifestyle had an improved recurrence-free survival (HL 4 vs HL0-1, HRadj 0.51 (95% CI 0.31-0.83) and overall survival (HL 4 vs HL 0-1, HRadj 0.52 (95% CI 0.38-0.70)). Stratifying these results for cancer stage (I-III) and tumor site (colon/rectum) did not alter estimated HR:s or 95% CI:s. Avoidance of smoking and being physically active were independently associated with improved recurrence-free survival and overall survival: non-smoking vs smoking HRadj 0.62 (95% CI 0.43-0.90), high vs low levels of physical activity HRadj 0.71 (95% CI 0.54-0-94)). Conclusions: Our study indicates that pre-diagnostic adherence to a healthy lifestyle may increase the recurrence-free and overall survival of patients with stage I-III CRC. Avoidance of smoking and being physically active were the strongest risk-reducing factors for these outcomes. [Table: see text]