Environmental Factors Affecting Risk of Urothelial Carcinoma

PATIENTS WHO LIVE in geospatial hotspots of urothelial carcinoma (UC) prevalence are less likely to be white, have a higher income or be tobacco users, and more likely to reside in close proximity to sources of industrial by-products and environmental pollutants (IBP/EP), according to researchers from Charlotte, NC, and Wynnewood, PA. The results of their study were presented during a session on “Optimizing personalized management of nonmuscle-invasive bladder cancer” at the 2021 ASCO Genitourinary Cancers Symposium.

“Risk factors for UC are well documented, with up to 65% of the incidence of UC attributable to tobacco use,” said study presenter Dr. Daniel C. Edwards (Levine Cancer Institute at Atrium Health, Charlotte). “Additionally, industrial and occupational exposure, such as coal mining, oil refining, tire manufacturers, painters, dye workers, etc, can be attributed to up to 7% of the incidence of UC.” Cancer has been associated with environmental exposures, but research into the effects of non-occupational environmental risk factors has been limited, he explained.

Dr. Edwards and co-investigators searched a multi-institutional database to identify patients diagnosed with UC between 2008 and 2018 in five Southeastern Pennsylvania counties (population approximately 4 million, annual incidence of UC around 1000). Using geocoded addresses and ArcGIS software, they determined the Getis-Ord-Gi* statistic and conducted hotspot analysis on the census-block level to identify UC hotspots. Pearson’s chi-square and Stu- dent’s t-test were used to compare demographics, clinicopathologic disease characteristics, and proximity to sources of IBP/EP. The correlation between patient and census block-level factors and living in a UC hot spot was tested with fitted univariate analyses and multivariable multilevel logistic random-intercept regression models.

A total of 5080 patients were identified, 148 of whom were correlated with one of 3 identified UC hotspots. Uni- variate analyses revealed that hot-spot patients were less likely to be tobacco users (odds ratio [OR], 0.24; P=0.004), be white (OR, 0.10; P<0.001), or have a higher income (OR, 0.73; P=0.005). They were also less likely to be alcohol users. “Perhaps most importantly, patients in hot spots were more likely to live near a traffic hot spot, an airport, sources of industrial discharge, and, specifically, sources of polycyclic aromatic hydrocarbon discharge,” Dr. Edwards said.

Multivariate analysis confirmed that patients residing in UC hotspots were less likely to use tobacco (OR, 0.11; P=0.045) and less likely to be white (OR, 0.02; P=0.004).

“In terms of polycyclic aromatic hydrocarbon exposure, hot-spot patients were 40 times more likely to live near a source of discharge. And hot-spot patients were significantly more likely to reside near high-density traffic hot spots,” Dr. Edwards added.

“Ultimately, spatially related clusters of UC may be associated with local or regional environmental exposures. And patients residing within UC hot spots may be more likely to be less educated, lower-earning, women, or non-white. Socioeconomic disparities may be associated with an increased likelihood of living in at-risk environments,” Dr. Edwards concluded. “In terms of clinical correlation, research such as this current study and future studies may help identify patients at risk for environmental exposures, allowing for interventions to be undertaken, including patient and primary care education, that might improve screening, earlier diagnosis, and treatment outcomes.”

Bibliography

Edwards DC, Yankelevich GR, Dreher PC, et al. Socio-environmental conditions associated with geospatial clusters of urothelial carcinoma: A multi-institutional analysis. J Clin Oncol. 2021;39(6, suppl):99. Abstract 392. doi: 10.1200/JCO.2021.39.6_suppl.392