Association of alcohol intake over the lifetime with colorectal adenoma and colorectal cancer risk in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial.

[BACKGROUND] Alcohol drinking is associated with higher colorectal cancer (CRC) risk, but research on lifetime alcohol drinking is limited. The objective of the current study was to estimate the association of lifetime alcohol drinking with incident colorectal adenoma and cancer.

[METHODS] US adults enrolled in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial reported alcohol intake during four age periods. Average lifetime alcohol intake was calculated as average drinks per week from age 18 years until study baseline. Alcohol intake patterns were defined by past and current drinking frequency. Among 12,327 participants with a negative baseline screen, 812 had an adenoma on the second screen. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for incident adenoma. During 20 years of follow-up, 1679 incident CRC cases occurred among 88,092 participants. Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% CIs for CRC.

[RESULTS] Current drinkers with an average lifetime alcohol intake of 14 or more drinks per week, compared with one drink or less per week, had a higher risk of CRC (HR, 1.25; 95% CI, 1.01-1.53), especially rectal cancer (HR, 1.95; 95% CI, 1.17-3.28). Consistent heavy drinking versus light drinking was positively associated with CRC risk (HR, 1.91; 95% CI, 1.17-3.12). Compared with current drinkers averaging less than one drink per week, former drinkers had lower odds of nonadvanced adenoma (OR, 0.58; 95% CI, 0.39-0.84). Current drinkers averaging from seven to less than 14 drinks compared with less than one drink per week had a lower risk of CRC (HR, 0.79; 95% CI, 0.64-0.97), especially distal colon cancer (HR, 0.64; 95% CI, 0.42-1.00).

[CONCLUSIONS] Consistent heavy alcohol intake and higher average lifetime alcohol drinking may increase CRC risk, whereas cessation may lower adenoma risk. Associations may differ by tumor site.