Tobacco and alcohol in relation to male breast cancer: an analysis of the male breast cancer pooling project consortium.
Level 3 - non-randomized controlled study
Pooled individual participant data analysis combining 10 cohort and 10 case-control studies
PubMed 25515550 · doi:10.1158/1055-9965.EPI-14-1009
What was done
The Male Breast Cancer Pooling Project consortium harmonized and pooled individual participant data from 10 case-control and 10 cohort studies, comprising 2,378 cases and 51,959 controls. Unconditional logistic regression was used to estimate study design-specific odds ratios (ORs) and 95% confidence intervals (CIs) for various tobacco exposures (smoking status, pack-years, duration, intensity, age at initiation, cigar, pipe, chewing tobacco, and snuff) and alcohol intake metrics (recent consumption, average grams/day, and beverage types). Estimates were combined across studies using fixed-effects meta-analysis, with stratification by age and body mass index.
What was found
Tobacco exposure in all assessed forms (cigarette smoking status, pack-years, duration, intensity, age at initiation, cigars, pipes, chewing tobacco, and snuff) was not associated with male breast cancer risk. Recent alcohol consumption, average grams of alcohol per day, and specific beverage types were also not associated with risk. Only very high recent alcohol consumption (>60 g/day) was tentatively associated with risk when compared to unexposed individuals (OR = 1.29; 95% CI, 0.97–1.71) or those consuming >0 to <7 g/day (OR = 1.36; 95% CI, 1.04–1.77). Age and body mass index stratification did not alter these associations.
Why it matters
Unlike in female breast cancer where alcohol is an established risk factor, this large international pooling project shows that tobacco and typical alcohol intake do not appear to play an etiologic role in male breast cancer.
Limits
Half of the included studies were case-control designs subject to recall and selection biases. The abstract does not evaluate breast cancer molecular subtypes or clinical staging, and pooling across disparate historical cohorts may introduce exposure measurement heterogeneity.
Cited by
- contradicts Alcohol consumption is a primary dietary factor fueling male breast cancer in genetically susceptible individuals.