Abstract
Reproductive factors are hypothesized to play a role in the incidence of bladder cancer and upper urinary tract cancer (UUTC, together, urothelial cancer). However, evidence regarding these associations is limited, particularly in Asian populations.
We analyzed data from 55,882 females ages 40 to 69 years, and performed Cox proportional hazards regression analyses with three types of adjustment, namely age; reproductive factor of interest and covariates in addition to age (conventional model); and other reproductive factors in addition to the multivariable adjusted model (reproductive model).
During an average of 20.2 years of follow-up, 194 urothelial cancer cases (145 bladder cancer cases and 49 UUTC cases) were identified. Early age at natural menopause (<44 years, compared with 49–51 years) increased bladder cancer risk in the reproductive model (HR, 2.09; 95% CI, 1.04–4.20). An association between urothelial cancer/bladder cancer and age at menopause, including both natural and surgical/induced, was significant in the reproductive model (HR, 1.74; 95% CI, 1.09–2.77; and HR, 1.94; 95% CI, 1.15–3.28, respectively). Early age at natural menopause was suggested to increase urothelial cancer risk in the reproductive model (HR, 1.78; 95% CI, 0.93–3.42).
Our findings suggest a significant association between age at menopause and incidence of urothelial cancer/bladder cancer among Asian populations. This study aids understanding the role of reproductive factors in urothelial cancer/bladder cancer incidence.
In Japanese populations, age at menopause is suggested to be associated with urothelial cancer/bladder cancer incidence, especially regarding early natural menopause.
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