Diabetes mellitus and risk of breast cancer: a meta-analysis.
Diabetes mellitus has been associated with an increased risk of several types of cancers, but its relationship with breast cancer remains unclear. We conducted a meta-analysis of case-control and cohort studies to assess the evidence regarding the association between diabetes and risk of breast cancer. Studies were identified by searching MEDLINE (1966-February 2007) and the references of retrieved articles. We identified 20 studies (5 case-control and 15 cohort studies) that reported relative risk (RR) estimates (odds ratio, rate ratio/hazard ratio, or standardized incidence ratio) with 95% confidence intervals (CIs) for the relation between diabetes (largely Type II diabetes) and breast cancer incidence. Summary RRs were calculated using a random-effects model. Analysis of all 20 studies showed that women with (versus without) diabetes had a statistically significant 20% increased risk of breast cancer (RR, 1.20; 95% CI, 1.12-1.28). The summary estimates were similar for case-control studies (RR, 1.18; 95% CI, 1.05-1.32) and cohort studies (RR, 1.20; 95% CI, 1.11-1.30). Meta-analysis of 5 cohort studies on diabetes and mortality from breast cancer yielded a summary RR of 1.24 (95% CI, 0.95-1.62) for women with (versus without) diabetes. Findings from this meta-analysis indicate that diabetes is associated with an increased risk of breast cancer.
Larsson
Susanna C
SC
Division of Nutritional Epidemiology, The National Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
Mantzoros
Christos S
CS
Wolk
Alicja
A
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001208:Asia; D015992:Body Mass Index; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000401:mortality; D016022:Case-Control Studies; D015331:Cohort Studies; D003920:Diabetes Mellitus / Q000453:epidemiology*; D005060:Europe; D005260:Female; D006801:Humans; D008297:Male; D008593:Menopause; D008875:Middle Aged; D009656:North America; D012307:Risk Factors