Kidney cancer rates are higher in the town of Merrimack compared to the rest of New Hampshire. And according to an investigation led by state officials and researchers from Dartmouth, more research is needed to determine the cause.
The study released this week is the third that has been published as part of a long-term project about cancer in Merrimack. The investigation began after Merrimack residents expressed concerns about their exposure to PFAS — a group of man-made chemicals that contaminated that community’s water.
The newly released results, known as Phase 3, included more information than previous studies. Looking at 27 years of cancer data, researchers determined the rate of kidney cancer in Merrimack is 38% greater than it is in the rest of New Hampshire.
The study also found a slight increase in the rate of kidney cancer in Manchester compared to the rest of the state.
However, the cause of higher rates of kidney cancer in those communities remains an open question for the group of scientists who worked on the project.
Megan Romano, a Dartmouth professor of epidemiology and one of the authors of the Phase 3 study, said the team considered everything that could be related: age, smoking, physical activity, rates of CT scans that can identify kidney cancer, and exposure to a host of environmental contaminants including arsenic, cadmium, trichloroethylene, uranium, radon and PFAS.
The Phase 3 study showed no indications of higher tobacco use or higher rates of CT scans in Merrimack, two factors that, according to the study, are "commonly associated with increased risk or detection of kidney cancer." The kinds of kidney cancers found at a higher rate in Merrimack are primarily connected to environmental or lifestyle causes, rather than hereditary conditions.
“If you want to make an epidemiologist squirm, ask us to talk about causality,” Romano said. “It’s hard to establish cause with a single study.”
Romano said the team’s objective was to determine whether a fourth phase to the investigation, which would seek to identify a more definitive answer about what is driving higher rates of cancer, was possible and worthwhile.
They decided the answer was yes.
“We did confirm that there continues to be an observation of an excess of kidney cancer in Merrimack,” she said. “That seems to suggest that there is something going on there that is worth unpacking and trying to understand.”
Researchers also noted that community members in Merrimack said they were generally willing to participate in research to help understand the causes of kidney cancer.
The ultimate hope, Romano said, is that further research will allow officials to intervene and reduce the rates going forward. But obtaining funding for future research could be challenging.
“The current funding climate for biomedical research is volatile,” researchers wrote in the study.
The first and second phase of the kidney cancer research were undertaken by state health officials, and the third phase was funded through a $500,000 contract between the New Hampshire Department of Health and Human Services and Dartmouth College.
Researchers said a study that tries to determine the cause of high kidney cancer rates would take at least five years and cost at least $500,000 per year. They suggested funding could come from the National Institutes of Health, the federal Department of Defense, or, less traditionally, a funding plan that combines support from private foundations and federal funding.
New Hampshire’s Department of Health and Human Services said the agency is “assessing potential activity that may stem from the Phase 3 study,” and that they continue to monitor cancer data, provide prevention resources, and “take steps to respond to community cancer concerns as appropriate.”
More information about the study can be found through Dartmouth and the New Hampshire Department of Health and Human Services.
