Researchers have identified a melanoma cancer cluster in 15 counties in Pennsylvania near or containing cultivated croplands, according to findings published in JCO Clinical Cancer Informatics. The research highlights that sunlight and areas of higher herbicide use may contribute to these significantly higher melanoma rates.
“Melanoma is often associated with beaches and sunbathing, but our findings suggest that agricultural environments may also play a role,” stated co-study author Charlene Lam, MD, MPH, Associate Professor of Dermatology, Penn State Health. “And this isn’t just about farmers. Entire communities living near agriculture, people who never set foot in a field, may still be at risk.”
Study Methods
Researchers explored the geospatial distribution of cases of melanoma in Pennsylvania to determine relationships with agriculture practices and patterns.
The study utilized an ecological design with data from Pennsylvania counties of invasive melanoma cases between 2017 and 2021 among adults 50 years and older. They also looked at agricultural patterns and practices, ultraviolet radiation, and demographics/socioeconomics.
Key Study Findings
The study found that the incidence of melanoma was 57.1% higher in a cluster of 15 counties in South Central Pennsylvania (P < .05), including 8 metropolitan counties and 7 rural counties.
Compared with counties outside of the cluster, these cluster counties had significantly more cultivated cropland (mean, 19.8% vs 6.9%; P < .001) and lands treated with herbicides (mean, 16.8% vs 6.5%; P < .001). “Our findings suggest that melanoma risk could extend beyond occupational settings to entire communities,” said Dr. Lam. “This is relevant for people living near farmland. You don’t have to be a farmer to face environmental exposure.”
Adjusted models showed that a 10% increase in cultivated cropland was independently associated with a 14% increase in melanoma incidence, and a 9% increase in herbicide-treated land was independently associated with a 13% increase in melanoma incidence.
Dr. Lam and colleagues are continuing to explore exposure risks in similar rural communities.
“Cancer prevention can’t happen in isolation,” said senior study author Eugene J. Lengerich, VMD, MS, Emeritus Professor of Public Health Sciences, Penn State College of Medicine. “This study demonstrates the importance of a ‘One Health’ approach, an understanding that human health is deeply connected to our environment and agricultural systems. If herbicides and farming practices are contributing to melanoma risk, then solutions must involve not just doctors, but farmers, environmental scientists, policymakers, and communities working together.”
Disclosure: The research was supported by the MPH Capstone Program and the Medical Student Research Project at the Penn State College of Medicine, as well as the University's Algin B. Garrett Professorship. For full disclosures of the study authors, visit ascopubs.org.
