The Illinois Department of Public Health said a recent review of cancer registry data found no evidence of an increase in glioblastoma cases in Piatt County, despite continued questions from Monticello residents about cases reported in the community. 

The statement came after a Freedom of Information Act request and repeated queries from CU-CitizenAccess.org. The agency said it was continuing to monitor reports as needed.

Caitlin McClain, a Monticello resident, has pressed for the department to investigate the prevalence of glioblastoma cases after she collected information on 49 cases in Monticello and 28 out-of-state that occurred over the last two decades.

Charity Greene, deputy director of communications for the state department, said in an email the department “last completed a cluster investigation in 2022,” before McClain began tracking data from her community.

Greene said the estimated yearly overall brain cancer rate is 6.7 cases per 100,000 people nationally over a five-year period, compared with 6 cases per 100,000 people in Illinois from 2004 to 2023. For glioblastoma specifically, she said the estimated yearly rate is 3.2 cases per 100,000 people nationally and 3.3 cases per 100,000 people in Illinois over the same 20-year period.

The department said its public analyses were conducted at the county level, not specifically for Monticello, as smaller geographic areas can create concerns about confidentiality and statistical reliability. It said it observed brain cancer rates in Piatt County that were within expected ranges compared with rural Illinois counties and statewide patterns.

The review came after McClain, whose father-in-law was diagnosed with glioblastoma in 2021, began tracking cases after noticing multiple diagnoses connected to people in the community. 

McClain has questioned whether the department has up-to-date information and accounts for some cases not being recorded correctly. She said state officials previously told her the cancer registry contained 19 glioblastoma cases over a 23-year period, a figure she believes undercounts the number of diagnoses.

“They’re not identifying every case that’s there,” McClain said. “When I asked about why there was a discrepancy, they explained to me that it takes two to three years for their epidemiology department and their specific cancer study area to pull the data from doctors and hospitals, and that oftentimes the cause of death is not listed as glioblastoma or brain cancer specifically … And that’s why they were saying they only had 19 cases in 23 years, but there’s well more than that.”

Glioblastoma is an aggressive form of brain cancer, and the cause of most glioblastomas is not known, according to Mayo Clinic. The medical nonprofit states most cases do not run in families, and inherited causes are rare.

McClain said she has been collecting glioblastoma cases connected to Monticello since 2023, along with additional cases involving people who later moved out of state. She said most of the cases were shared with her directly by relatives of the people diagnosed.

The department described its cancer registry reviews as ongoing and said there is not a single formal closure date for the review. Newly reported cancer cases are reviewed each year as part of routine cancer surveillance, according to the public health department.

Cancer cluster evaluation requires updated, long-term data

Dr. Rebecca Smith, an epidemiologist at the University of Illinois, said evaluating a possible cancer cluster depends on comparing the number of cases with the population at risk and with patterns over time.

“Incidence is the number of new cases divided by the population at risk,” Smith said. “That’s really important because you might see a lot of new cases of a rare cancer in Chicago and that would not be as concerning as in Monticello because there’s just a lot of people in Cook County.”

Smith said long-term data is also needed to determine whether the number of cases is outside what would normally be expected.

She also said scientific conclusions are built gradually, which can make the public health process feel slow to people waiting for answers.

“It is always so hard to communicate when you don’t have strong answers,” Smith said. “We like cut and dry, we like black and white. It’s very hard to explain when there is no black and white.”

Community still seeking answers to little reply from state

McClain said she shared her case information with the state, including addresses for people affected, with permission from family members. She said she was told the public health department would conduct a cancer review, but she has not received clear updates on the process since her last communication with the department last summer.

“I don’t know if there’s been any forward movement on [the cancer review] because there has been zero communication from [the public health department],” McClain said.

McClain said she wants the state to provide a clearer explanation of what it reviewed, how her information was considered and whether any additional steps will be taken.

Her concerns also extend beyond the cancer registry review, including questions about possible environmental exposures in and around Monticello.

“What I found were basically three things: [Those diagnosed with glioblastoma] were a lot of farmers, or spouses and children of farmers, or they lived next to a field or grew up next to a field,” McClain said.

The public health department said it reviewed concerns about pesticide exposure in Monticello but found no evidence of recent pesticide misuse in the area. The department said the scientific literature it reviewed showed links mainly between glioblastoma and occupational pesticide exposure, not general residential exposure.

The department’s own cancer registry page says there is no study the department can conduct that would show what caused cancer among residents in a community, and that no single study — or even many epidemiological studies — can explain why an individual person developed cancer.

Still, McClain said residents are looking for clearer communication about the state’s review.

“Residents want to know what the state reviewed, what it did not review and what would trigger additional action,” McClain said.

In other Illinois cancer assessments, including a public-facing Lake County assessment involving ethylene oxide concerns, the public health department has published background, methodology and updates online.

McClain said she understands state officials may be cautious as questions about a possible cancer cluster can raise concerns about responsibility or restitution, but she said her focus is on preventing future harm, not financial compensation.

“There’s no amount of money that could ever be paid to correct what has been done,” McClain said. “But we also need to protect families in the future.”