Antibiotics and the risk of breast cancer.
BACKGROUND
Two recent studies found a positive association between antibiotic use and the risk of breast cancer.


METHODS
Using information from the U.K. General Practice Research Database, we identified 1268 cases of incident breast cancer (40- to 79-year-old women diagnosed in 1987 to 2002 who had at least 6 years of history recorded in the General Practice Research Database) and 6291 female controls matched to the cases on age, general practice, and duration of history recorded in the General Practice Research Database. We ascertained antibiotic prescriptions (penicillins, cephalosporins, sulfonamides, macrolides, tetracyclines, quinolones, metronidazole, and nitrofurantoin) recorded up to 1 year before the index date.


RESULTS
Odds ratios (95% confidence intervals) of breast cancer for 0, 1-50, 51-100, 101-500, and 501 or more cumulative days of antibiotic use were 1.0 (reference), 1.0 (0.9-1.2), 0.9 (0.7-1.2), 0.9 (0.7-1.3), and 1.2 (0.6-2.4).


CONCLUSIONS
These data do not support the hypothesis that antibiotic use is associated with an increased risk of breast cancer.
Kaye
James A
JA
Boston Collaborative Drug Surveillance Program, Boston University School of Medicine, Lexington, MA, USA. jkaye@bu.edu
Jick
Hershel
H
D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000453:epidemiology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008875:Middle Aged; D012306:Risk; D006113:United Kingdom / Q000453:epidemiology
D000900:Anti-Bacterial Agents