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What Does It Take to Confirm a Cancer Cluster?

— Suspicions are raised at a New Jersey high school, but the road ahead is likely a long one

Ƶ MedicalToday
A computer rendering of a cluster of people forming the shape of a map location icon.

An environmental scientist from New Jersey has discovered in people who went to a single high school over about a 30-year period of time.

News reports have already begun to refer to a "cancer cluster" at Colonia High School in Woodbridge, New Jersey. But experts note that it's a long road from detecting a strong signal like this, to becoming a proven "cluster" -- and then it can be even more difficult to determine a cause, which is sometimes never found.

Michael Gochfeld, MD, PhD, a professor emeritus at Rutgers University's Environmental and Occupational Health Sciences Institute, told Ƶ that the Colonia High School case is compelling, and credited organizer Al Lupiano for the diligent work he's been doing.

Lupiano graduated Colonia High School in 1989. He was diagnosed with an acoustic neuroma 10 years later. Then, in 2021, his wife was also diagnosed with an acoustic neuroma -- on the same day that his sister was diagnosed with glioblastoma multiforme, a far more aggressive disease. Both his wife and his sister were former students of Colonia High School.

Lupiano's sister died of her cancer in February, and Lupiano pledged to look deeper into the question of whether their tumors could be tied to an exposure at the school. He took to , and his efforts took off, with more than 100 former students and teachers reporting that they'd been diagnosed with brain tumors, half of which were deemed cancerous, .

Gochfeld noted that in a typical cluster, experts are generally looking for the same type of cancer. While the Colonia cases can broadly be described as brain tumors, they do involve different types of cancer, he noted.

Nonetheless, determining whether this is a true cluster will involve looking at the expected rates of a particular cancer in this population over a certain time period.

"They'll look at the number of cases, compared to the number expected. If there's a real excess, then it begins to look like a real cluster in time and in space," Gochfeld said. "If there's not an excess, then it's a pseudo cluster or a putative cluster, but it doesn't meet the statistical requirements of a cluster."

Gochfeld cited a previous example from another New Jersey town, from about 40 years ago, in which a large number of .

Five children in one school alone developed the disease, and after determining expected rates, epidemiologists concluded "it was highly improbable that by chance alone, five leukemia cases would end up in that school," Gochfeld said.

The state conducted a subsequent detailed investigation anticipating they'd find the smoking-gun carcinogen that was responsible -- but they never did.

"They went through very detailed questionnaires, including about their homes, their families, their upbringing, what they did in school when they were in school, and they could not find something the leukemia cases had in common that the [controls] didn't," Gochfeld said. "So there is an example of a true cluster -- as it met the statistical criteria for being a cluster -- but nonetheless, they couldn't find the cause. Which was certainly disappointing."

In other instances in New Jersey, cancer cluster causes have been found, Gochfeld said. In Toms River Township, for instance, investigators determined that was the likely culprit in a childhood leukemia cluster in that town.

Lupiano suspects the culprit at Colonia may originate with the Middlesex Sampling Plant, which from the 1940s to the 1960s served as a processing plant for uranium ore that was subsequently shipped around the country. The site was remediated and Lupiano said some of the sediment may have been trucked to the site of the high school during its construction in 1967.

Since Lupiano first raised concerns, an environmental engineering company has been conducting radiation surveys at Colonia High School, and both the New Jersey Department of Health and the New Jersey Department of Environmental Protection that they are working with Woodbridge officials as well as CDC's Agency for Toxic Substances and Disease Registry "to provide an assessment of the potential health effects." The Environmental Protection Agency also acknowledged being aware of the concerns, .

Still, Gochfeld warned that it's likely to be a difficult road ahead for Lupiano and investigators. When a cancer latency period is long, he said, as is typically the case with brain cancers, it is much harder to determine a cause. Nor is this like a workplace exposure, where clusters are easier to determine because employees were exposed to the same known carcinogen over the same period of time, and then developed the same malignancy.

Nonetheless, Gochfeld said Lupiano has "done a lot of work, and he's made it very clear that he's going to pursue this, whether the state comes through or not."

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    Kristina Fiore leads MedPage’s enterprise & investigative reporting team. She’s been a medical journalist for more than a decade and her work has been recognized by Barlett & Steele, AHCJ, SABEW, and others. Send story tips to k.fiore@medpagetoday.com.