Dartmouth feasibility study finds statistically higher kidney cancer rates in Merrimack; pilot shows community willingness to participate in larger research

A Dartmouth team presenting to the Commission for the Study of the Environmental and the Public Health Effects of Per- and Polyfluorinated Chemicals reported that kidney cancer incidence in Merrimack, New Hampshire, remains higher than expected and that preliminary pilot work shows residents are willing to participate in expanded research.

The phase 3 feasibility study, completed in cooperation with New Hampshire DHHS and using New Hampshire State Cancer Registry data from 1995–2021, aimed to determine whether a larger study could test links between environmental exposures and the observed excess kidney cancers. “The purpose of the study was to gather information to see if it's likely that a future larger study will show whether or not the cancer cases relate to a common cause,” said Dr. Megan Romano, who presented Dartmouth’s findings to the commission.

Dartmouth described four study components: community engagement, cancer-registry analysis, a research-feasibility survey, and a pilot study. Community engagement included four “engagement studios” with 30 discussants and a community advisory board. The research-feasibility survey (fielded in November 2024 to a representative New Hampshire online panel of 1,183 adults) found broad willingness to participate in future research and to provide water and biological samples. In the pilot, the team enrolled 105 completed participants (from 140 verified eligible respondents) and collected questionnaire data and selected biosamples.

Registry analysis and statistical findings

Using standardized incidence ratios (SIRs) and 95% confidence intervals to adjust for age distribution, Dartmouth reported an SIR of 1.38 (95% CI 1.05–1.77) for Merrimack for 2013–2021 after excluding renal pelvis tumors. The team indicated that clear cell renal carcinoma appears to be an important driver of the excess in Merrimack. Dartmouth also reported a newly observed excess in Manchester (SIR 1.18; 95% CI 1.02–1.35), which the presenters said warrants follow-up but should be interpreted cautiously as a new finding.

Dr. Romano and the team emphasized that SIRs indicate excess or deficit in incidence but do not identify causation. The presenters described work to harmonize pathology and registry coding across the 1995–2021 period to reduce misclassification and duplicate counting.

Pilot study results and operational lessons

The pilot preferentially recruited adults residing in or who had lived/worked in the nine-town Merrimack area for at least one year. Of the 105 participants who completed the study, nine reported a history of kidney cancer (roughly 8.6% of the pilot sample), which Dartmouth said exceeded the roughly 3% prevalence expected in a random sample and suggested the pilot could successfully recruit cancer patients for future study.

Key pilot findings included: - Demographics: mean age about 56 (range 21–87); 67% women; 41% currently living in Merrimack. - Water sources: 65% public water, 31% private wells; among private-well users, 48% had tested for arsenic and 45% had tested for PFAS in the past five years. - Participant willingness: 95% willing to provide a water sample; ~87% willing to provide a blood sample; lower willingness to share medical records. - Biospecimen collection: the team successfully mailed and processed self-collected finger-prick blood kits and toenail clippings but saw lower-than-expected kit return rates and participant hesitancy (the team had offered $25 for toenail clippings). The pilot also revealed substantial automated “bot” signups (3,005 interest responses that were flagged and excluded), which the team said they were able to filter and learn from for future recruitment.

Data linkage opportunity

Dartmouth reported collaboration with New Hampshire Department of Environmental Services (DES) staff who provided private well PFAS sampling records. The team found it feasible to match pilot participants’ residential histories to DES drinking-water testing records for exposure modeling, but noted preparing those data for research use will require substantial time and expertise.

Next steps and funding outlook

Dartmouth estimated a future, definitive study would likely require an NIH R01-scale grant (approximately five years, about $500,000 per year in direct costs) and said the pilot provides preliminary data to support such applications. The presenters noted the current federal funding climate is uncertain and urged realistic timelines: NIH review cycles and potential resubmissions typically add months or years to project start dates.

Dartmouth submitted a technical final report and an accessible two-page lay summary to New Hampshire DHHS; both will be posted on the New Hampshire State Cancer Registry website. An ancillary pilot-study report was pending completion at the time of the presentation.

Why it matters

The statistical excess in Merrimack and a new signal in Manchester do not by themselves establish cause, but they meet the threshold—statistically significant SIRs with confidence intervals excluding 1—that Dartmouth and DHHS presenters said justifies further investigation. Community members and commission discussion emphasized interest in broader endocrine and renal health outcomes (for example, thyroid disease) as a potential adjunct to cancer-focused research.

Commission discussion and community concerns

Commissioners and community members praised Dartmouth’s engagement and the pilot’s recruitment success, and several speakers urged attention to thyroid and blood-borne cancers in future work. Dartmouth and DHHS staff said they will consider how to package future proposals to reflect both cancer endpoints and earlier biomarkers of renal or endocrine dysfunction, while noting that specific study design choices must be weighed for scientific rigor and funder priorities.

Dartmouth requested that the commission and DHHS consider letters of support for future grant applications; the team said it will notify the commission if funding is secured.

Ending

Dartmouth concluded that a larger study appears feasible but will require substantial funding, time for biospecimen collection, and careful exposure-data preparation. The team committed to share the pilot ancillary report and to continue working with DHHS and community advisors on next steps.