Dietary soy and increased risk of bladder cancer: a prospective cohort study of men in Shanghai, China.
To verify our previous finding of a positive association between dietary soy and bladder cancer risk, we examined the association in a second, geographically distinct prospective cohort of Chinese subjects, the Shanghai Cohort Study. Briefly, 18,244 men aged 45-64 years were recruited between January 1986 and September 1989. As of December 31, 2002, 61 incident bladder cancer cases were identified. Information on soy consumption was obtained through in-person interviews at baseline using a food frequency questionnaire. Cox proportional hazard regression methods were used to estimate relative risks (RR) and their corresponding 95% confidence intervals (CI), with adjustment for age (years) at baseline interview, level of education and other potential confounders. Compared to men consuming soy less than once a week, the RR (95% CI) for those who consumed soy 1-<3 times per week, 3-<7 times a week and daily were 2.05 (0.80-5.29), 2.45 (0.89-6.76) and 4.61 (1.57-13.51), respectively (p for trend = 0.004), after adjustment for age, cigarette smoking and level of education. The soy-bladder cancer risk associations in smokers and non-smokers were comparable. The soy-bladder cancer relationship became stronger when the analysis was restricted to subjects with 2 or more years of follow-up.
Sun
Can-Lan
CL
USC/Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, Los Angeles, CA 90033-9176, USA. canlun@usc.edu
Yuan
Jian-Min
JM
Wang
Xue-Li
XL
Gao
Yu-Tang
YT
Ross
Ronald K
RK
Yu
Mimi C
MC
D002681:China / Q000453:epidemiology; D004032:Diet; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D012737:Sex Factors; D045730:Soy Foods; D001749:Urinary Bladder Neoplasms / Q000453:epidemiology / Q000209:etiology*