Several new studies presented at the Annual Scientific meeting of the American Urological Association (AUA) highlight the important links between smoking and bladder cancer. In one, smoking intensity was linked to survival outcomes in bladder cancer patients, while two others show that electronic cigarettes likely contribute to bladder cancer risk.
“This research underscores the importance of smoking cessation (of both traditional and e-cigarettes) for people with bladder cancer, and people looking to avoid it,” said Sam S. Chang, MD, MBA, of Vanderbilt–Ingram Cancer Center in Nashville, who moderated the session with the new studies, in a press release.
The first study, led by Luis Felipe Sávio, MD, of the University of Miami Miller School of Medicine in Florida, used the Florida Cancer Data System to identify 14,077 bladder cancer patients who smoked. Of those, 25% smoked less than one pack of cigarettes per day, 63% smoked between one and two packs per day, and 12% smoked more than two packs per day.
The median overall survival (OS) for the full cohort was 4 years, and the 5-year OS rate was 43.7%. For those who smoked less than one, one to two, and more than two packs per day, the median OS was 4.2 years, 3.9 years, and 4.1 years, respectively; 5-year OS rates for these groups were 45.1%, 43.1%, and 43.6%, respectively. Using the group that smoked less than one pack as a reference, those smoking one to two packs daily had a hazard ratio (HR) for mortality of 1.11 (95% CI, 1.06–1.16; P < .001); for more than two packs per day, the HR was 1.08 (95% CI, 1.00–1.16; P = .042).
The other studies focused on e-cigarettes. Thomas Fuller, MD, of the University of Pittsburgh, led a study that compared the urine of 13 e-cigarette users to 10 non-smokers, analyzing them for five known bladder carcinogens: benz(a)anthracene, benzo(a)pyrene, 1-hydroxypyrene, o-toluidine, and 2-naphthylamine.
Two of those five molecules—o-toluidine and 2-naphthylamine—were found in urine of 12 of the 13 e-cigarette users. They were found in none of the control participants, and the other three carcinogens were not found in any of the participants.
In the other study, led by Hyun-Wook Lee, PhD, of New York University School of Medicine, researchers using a mouse model found that e-cigarette smoke can induce tumorigenic DNA damage in bladder mucosa. This was also seen in an in vitro experiment using human urothelial cells.
“These studies raise new concerns about the harmful impact of e-cigarettes on bladder cancer,” Chang said. “We’ve known traditional smoking raises bladder cancer risk, and given the surge in popularity of e-cigarettes, it’s imperative we uncover any potential links to e-cigarette smoke and bladder cancer.”