Alcohol drinking and breast cancer risk: an evaluation based on a systematic review of epidemiologic evidence among the Japanese population.
BACKGROUND
We reviewed epidemiological studies on alcohol drinking and breast cancer among the Japanese population. This report is one among a series of articles by our research group evaluating the existing evidence concerning the association between health-related lifestyles and cancer.


METHODS
Original data were obtained from MEDLINE searches using PubMed or from searches of the Ichushi database, complemented with manual searches. Evaluation of associations was based on the strength of evidence and the magnitude of association, together with biological plausibility as previously evaluated by the International Agency for Research on Cancer.


RESULTS
Three cohort studies and eight case-control studies were identified. There were inconsistent results regarding alcohol drinking and breast cancer risk among cohort studies. A significant positive association was observed in one, but another showed nonsignificant inverse association. Out of the eight case-control studies, two studies showed a significantly increased risk among women who drink daily and who had higher intake of alcohol, respectively. Experimental studies have supported the biological plausibility of a positive association between alcohol drinking and breast cancer risk.


CONCLUSIONS
We conclude that epidemiologic evidence on the association between alcohol drinking and breast cancer risk remains insufficient in terms of both the number and methodological quality of studies among the Japanese population.
Nagata
Chisato
C
Department of Epidemiology and Preventive Medicine, Gifu University Graduate School of Medicine, Gifu, Japan.
Mizoue
Tetsuya
T
Tanaka
Keitaro
K
Tsuji
Ichiro
I
Wakai
Kenji
K
Inoue
Manami
M
Tsugane
Shoichiro
S
D000428:Alcohol Drinking / Q000009:adverse effects* / Q000453:epidemiology; D001943:Breast Neoplasms / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D012307:Risk Factors