Reproductive Life History as Gastric Cancer Risk for Females : Case-Control Study

Abstract

The purpose of this study was to investigate whether the reproductive life history, including hormonal environment, was a risk factor for gastric cancer in females by age groups or by histological subgroups. A case-control study with incident cases accompanied by individually matched one or two controls was carried out, using self administered questionnaire which included personal profile, smoking and drinking habits, dietary habits, past history of disease and reproductive life history. Analysis was made for 116 females cases and matched 144 controls separately by two histological type subgroups (differentiated and undifferentiated type) and by two age groups (young and older), using proportional hazard model to obtain relative risks with 95% C.I. For the undiffer- entiated gastric cancer in female under 40 years of age, mean of cumulative estradiol concentration (CEC) during all pregnant period and mean pregnant period per pregnancy revealed increased relative risk (R.R.) of 7.7 (95% C.I.: 1.41-41.75) (for each 1 ng/ml) and 3.1 (95% C.I.: 1.01-9.55) (for each 10 weeks), respectively. In the same group, 4 bowls or more rice consumption per day and drinking showed significant protective effect (R.R.: 0.20, 95% C.I.: 0.04-0.90 and R.R.: 0.23, 95% C.I.: 0.07-0.70, respectively). For differentiated gastric cancer in both age groups and undifferentiated one in older female, these factors stated above have no striking effect for gastric cancer occurrence. For differentiated type, several dietary habits were suggested to be risk factors for gastric cancer, although they were not statistically significant. On the other hand, for undifferentiated type, this tendency was not observed. This study suggests that etiologic factors for gastric cancer might be differed between histological types, and that undifferentiated type gastric cancer in young female with pregnancy has some etiological relation with reproductive histories. J Epidemiol, 1995; 5 : 177-185.