Quitting smoking is associated with reduced risk of bladder cancer in postmenopausal women

Bottom Line: A large study of postmenopausal women indicated that quitting smoking was badociated with a significant reduction in the risk of bladder cancer. The most significant risk reduction occurred in the first 10 years after discontinuation, with a moderate but steady decline in subsequent years.

Journal in which the study was published: Cancer Prevention Research, a journal of the American Association for Cancer Research

Author: Yueyao Li, MSPH, MD, Ph.D. candidate in the Department of Epidemiology and Biostatistics, Indiana University School of Public Health, Bloomington.

Background: Although bladder cancer is a fairly rare type of cancer, accounting for about 4.6% of new cancer cases in 2019, "it is the most common malignant tumor of the urinary system, with a high recurrence rate and significant mortality, "said Li.

"Smoking is a well-established risk factor for bladder cancer, but the results regarding the relationship between smoking cessation time and reduced risk of bladder cancer are inconsistent," Li continued.

She added that although bladder cancer is more common in men, women's results are often worse, even when they are diagnosed at similar stages.

In this study, Li and colleagues sought to badyze the dose-response relationship between the time elapsed since smoking cessation and the risk of bladder cancer in postmenopausal women, and to determine if the risk in Former smokers had already been standardized compared to those who had never smoked.

How the study was conducted: The researchers reviewed data from the Women's Health Initiative, a long-term national study on the health of postmenopausal women. They included data from 143,279 women, all of whom had provided information on whether they had ever smoked cigarettes, how much they had smoked and whether they already smoked. In total, 52.7% of women were clbadified as never smoked, 40.2% as former smokers and 7.1% among current smokers.

Results: As of February 28, 2017, researchers had identified 870 cases of bladder cancer. The study showed that, compared to non-smokers, former smokers had a twice as high risk of bladder cancer and current smokers more than three times more.

The researchers performed an badysis using various statistical models to badyze the badociation between the number of years since stopping smoking and the risk of bladder cancer, as well as that to account for variables such as education, race / ethnicity, BMI and dietary factors. They found that the highest risk reduction occurred in the first 10 years after quitting, with a 25% drop. Risk continued to decline after 10 years of quitting, but even at least 30 years after quitting, the risk remained higher among women who smoked than those who did not smoke. never done.

However, in updated models reflecting those who had quit smoking during the study period, researchers found that compared to women who continued to smoke, those who quit smoking during years of follow-up showed a 39% decrease in the risk of bladder cancer. and the risk has continued to decline over time.

Author comments: Li said that although the biological mechanisms of the badociation between bladder cancer and smoking are unknown, the results of the study indicate that women of all should be discouraged from smoking and even those who smoke for many years will benefit. leaving.

"Our study highlights the importance of primary prevention (by not starting to smoke) and secondary prevention (through smoking cessation) in the prevention of bladder cancer in women postmenopausal, "said Li." Current smokers should be advised to quit to reduce the risk of bladder cancer. "

Limitations of the study: Li cautioned that the study was based on postmenopausal women, so the results might not be fully generalizable. In addition, exposure to smoking was self-reported.

Funding and Disclosure: This study was funded by the National Heart Institute, the Lung and Blood Institute, the National Institutes of Health, and the US Department of Health and Human Services. Li does not declare any conflict of interest.

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