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AUA 2019: Studies Highlight Potential Bladder Cancer Risks

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Electronic cigarettes (e-cigarettes), exposure to certain environmental factors, and human papillomavirus (HPV) infection may increase the risk of developing bladder cancer, according to new data presented this week at the 2019 Annual Meeting of the American Urological Association (AUA). The following abstracts were presented in a press briefing moderated by Sam Chang, MD, MBA, the Patricia and Rodes Hart Endowed Chair of Urologic Surgery at Vanderbilt University Medical Center.

Proximity to Oil Refineries and Risk of Bladder Cancer

Exposure to certain aromatic compounds generated by oil refineries—including benzene and aromatic amines—is a known risk factor for bladder cancer. Using data from the Texas Cancer Registry, U.S. Census data, Ray-Zack et al identified more than 45,500 patients diagnosed with bladder cancer and mapped their location relative to the locations of 28 active refineries in the state. Cancer incidence was compared based on proximity to the refineries.

Key findings include:

  • More than 5,500 of cases were within 10 miles of an oil refinery
  • Bladder cancer risk was greater among those living within a 10-mile radius of a refinery than for those living further than 10 miles away (relative risk [RR] = 1.19, 95% confidence interval [CI] = 1.08–1.31)
  • Bladder cancer risk was significantly greater for males than females (RR = 3.41; 95% CI = 3.33–3.50).

E-Cigarette Smoke as a Potential Bladder Carcinogen

Tobacco smoke is a known risk factor for bladder cancer, with smoking being directly related to about half of bladder cancers in men and women. E-cigarettes are a popular new alternative to combustible cigarettes, and are thought to be safer. In this early study on a mouse model by Tang et al, researchers built on previous studies on the potential of e-cigarette smoke to induce DNA damage and tested their hypothesis that e-cigarette smoke was cancer-inducing, examining both direct and secondary exposures after 52 weeks.

Key findings include:

  • No tumors were found; however, simple urothelial hyperplasia—a precancerous lesion —was more evident in mice exposed to e-cigarette smoke compared to those who were not.
  • Sixty percent (18/30) of mice exposed directly to e-cigarette smoke and 6.3% (1/16) exposed to secondary e-cigarette smoke developed urothelial hyperplasia.
  • Urothelial hyperplasia lesions were found to have significant expansion of Krt5-positive basal urothelial cells and marked elevation of certain cell proliferation markers (MCM2 and PCNA).

The Association of HPV and Bladder Cancer

Reinstatler et al used data from the National Health and Nutrition Examination Survey to assess whether serum levels of HPV18, HPV16, HPV11, and HPV6 could be correlated with bladder cancer incidence. From 2007–2010, out of 155.6 million Americans, HPV-positive rates were as follows:

  • HPV18: 5.5%
  • HPV16: 13.2%
  • HPV11: 6.4%
  • HPV6: 17.4%.

Researchers then identified 443,948 cases of bladder cancer in this population.

Key findings include:

  • After controlling for race, gender, and smoking status, increasing body weight and HPV6 positivity were associated with an increased risk of bladder cancer diagnosis.
  • HPV6-positive serology was associated with a higher prevalence of bladder cancers (18.1% vs 17.6%).
  • Bladder cancer prevalence was higher among males (80% vs 53%) and those of Caucasian race (93% vs 66%).
  • HPV11 was associated with decreased odds of bladder cancer diagnosis.

“We've known for some time that smoking cigarettes can increase the risk of developing bladder cancer, and that certain environmental exposures are also risk factors,” said press briefing moderator Dr. Chang. “These studies take a new approach to examining risks—including vaping—and highlight new insights into who may be at greater risk of developing this cancer.”

Disclosure: For full disclosures of the study authors, visit auajournals.org.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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