Early onset of menopause is associated with a higher risk of bladder cancer among women with a history of smoking, according to study findings presented at the 34th European Association of Urology (EAU) Congress in Barcelona, Spain.
In a study of female registered nurses in the Nurses’ Health Study (NHS) and Nurses’ Health Study II (NHS II), investigators found that, among women who had ever smoked, menopause onset at age 45 years or younger was associated with a significant 66% increased risk of bladder cancer compared with menopause onset at age 50 years or older, after adjusting for multiple variables, Mohammad Abufaraj, MD, of the Medical University of Vienna in Austria, and colleagues reported. The investigators found no link between age of menopause onset and bladder cancer among women who never smoked.
Among the 116,110 and 113,974 participants in NHS and NHS II, respectively, 629 incident cases of bladder cancer developed during a median follow-up of 29 years, Dr Abufaraj’s team reported.
“Smoking remains the most important risk factor for bladder cancer,” Dr Abufaraj said in a statement issued by EAU. “Our data also revealed that it is unlikely that female factors such as age when periods begin, number of pregnancies, oral contraceptive use or the use of hormone replacement therapy are associated with bladder cancer risk. Smoking is associated with earlier age at menopause thereby further increasing the risk of developing bladder cancer.”
In the EAU statement, Arnulf Stenzl, MD, chairman of the EAU Scientific Congress Committee, who was not involved in the new study, said “smoking clearly sticks out as the underlying reason for the increased incidence of bladder cancer. However, we need to remain open to other factors causing bladder cancer, such as hormonal changes leading to early menopause; this work indicates that these changes may themselves be a result of long term nicotine exposure.”
Abufaraj M, Shariat SF, Moschini M, et al. The impact of hormones and reproductive factors on the risk of bladder cancer in women: Results from the Nurses’ Health Study and Nurses’ Health Study II. Presented at the European Association of Urology 2019 congress in Barcelona, Spain, held March 15-19. Abstract 175.