Age at Menopause May Play a Role in Bladder Cancer Risk

Women who experience menopause before age 45 are at an increased risk of developing bladder cancer — one that is even higher if the individual also smoked, according to recent study findings.

Researchers in the United States and Europe looked at more than 220,000 registered nurses who were enrolled in the Nurses’ Health Study (NHS) and NHS2, which has studied the health outcomes of American nurses since 1976. They performed self-questionnaires every other year regarding reproductive and hormonal factors, smoking history and other relevant data.

In the study, the researchers explained that although three quarters of new bladder cancer cases occur in men, women are more likely to present with more advanced disease and less favorable outcomes.

“We (were) trying to find a plausible explanation for the discrepancy in bladder cancer incidence between men and women by evaluating potential protective factors in women,” Mohammad Abufaraj, M.D., from the Medical University of Vienna, said in an interview with CURE. “Therefore, our study population comprised of two large U.S. female prospective cohorts.”

The studies showed 441 cases of bladder cancer during up to a 36-year follow-up. In the NHS trial, 22,566 (21.3%) women were menopausal at the start of it compared with 2,723 women (2.4%) in NHS2.

Compared with women who had menopause after 50, women younger than 45 who went into menopause were 45% more likely to have bladder cancer. In addition, the risk of bladder cancer was 53% greater if the women had smoked.

“Menopause at younger age implies shorter reproductive years. For example, shorter exposure to female sex-hormones,” Abufaraj said. “Female sex-hormones were postulated to have a protective role in bladder cancer risk. However, this interaction should be explained among other risk factors of bladder cancer such as smoking. In fact, smoking is the most important risk factor for bladder cancer and is well-known to be related to early menopause.”

Around 1 in 20 women undergoes early menopause before the age of 45 and the average age at menopause is 51 years in developed countries, explained the researchers.

The study showed no association of age at the first occurrence of menstruation, age at first birth, oral contraceptive use and postmenopausal hormone with bladder cancer risk.

Bladder cancer is one of the most common cancers diagnosed in the U.S. This year, the American Cancer Society estimates that more than 80,000 news cases of the disease will be diagnosed — around 19,000 will be in women.

“Our findings raise the awareness of physicians, as well as women, to evaluate ‘common’ urinary symptoms in women who experienced premature menopause seriously,” Abufaraj said, adding that further studies are needed. “Such studies should also investigate the full spectrum of bladder cancer paradox; for instance, the worse outcome of bladder cancer in women compared (with) men.”