Collaborative Review – Bladder CancerGender and Bladder Cancer: A Collaborative Review of Etiology, Biology, and Outcomes
Introduction
Bladder cancer is the ninth most common malignancy and 13th most common cause of cancer death worldwide [1]. According to estimates, 74 000 cases of urothelial carcinoma of the bladder (UCB) will be diagnosed in the USA in 2015, with 16 000 bladder cancer deaths [2]. Interestingly, it has been found that bladder cancer diagnosis is three to four times more common in men than in women, so that UCB represents the fourth most common cancer in men in the USA and the eighth most common cause of cancer death [2], [3]. Moreover, between 1998 and 2008, the rate of increase in the number of bladder cancer cases in the USA was 25% faster in men than in women [4]. Numerous explanations for this gender discrepancy in incidence have been offered, including disparate exposures to bladder cancer risk factors and the potential for sex steroid hormone regulation.
At the same time, women diagnosed with bladder cancer are more likely to have locally advanced tumors at the time of diagnosis [5]. Furthermore, female gender has been reported—albeit not uniformly—to be associated with higher risks of disease recurrence, progression, and mortality after treatment [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24]. Understanding the factors associated with gender disparities in bladder cancer presentation, evaluation, and management could thus facilitate improvements in the timeliness and intensity of health care delivery. In turn, such efforts offer the potential to reduce the magnitude of the gender-based disparities observed for bladder cancer outcomes.
The aim of the present review was to assess the literature on potential biologic mechanisms underlying the gender discrepancy in bladder cancer incidence and the epidemiologic evidence demonstrating disparities in bladder cancer evaluation, management, and outcomes between men and women.
Section snippets
Evidence acquisition
A literature search using the MEDLINE/Pubmed database was performed to identify original articles, review articles, and editorials published between 1966 and 2015 that included an analysis of the association of gender with bladder cancer. The search was limited to studies published in the English language. No manual search of meeting abstracts was performed. The following keywords were used during the search: urothelial cancer, bladder cancer, sex, gender, males, females, men, women, androgen
Impact of gender-specific risk factor exposure on the gender discrepancy in bladder cancer incidence
The association between risk factor exposures and bladder cancer development has been extensively investigated [25], [26]. In particular, cigarette smoking has been well established as the most common risk factor for bladder cancer diagnosis [27]. Currently, an estimated 42.1 million US adults smoke, corresponding to 15.3% of adult women and 20.5% of adult men [28]. The global modeled age-standardized prevalence of smoking in the population older than 15 yr decreased from 41.2% in 1980 to 31.1%
Conclusions
The relationship between gender and UCB is complex, and is probably influenced by both biologic and epidemiologic factors. While the incidence of bladder cancer is three- to fourfold higher in men, women are diagnosed with more advanced stage tumors. Moreover, consistent but not universal data suggest higher mortality from bladder cancer among women compared to men. Numerous potential contributing factors may explain these demographic trends, including the importance of the sex steroid hormone
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