A New Jersey high school is currently investigating a potential cancer cluster of more than 100 brain tumor diagnoses among students and staff over almost three decades—but experts warn that pinpointing an exact cause will likely be difficult.

Related: ICD-10 tumor site map

More than 100 cancer cases at a New Jersey high school

Al Lupiano, an environmental scientist, was diagnosed with an acoustic neuroma, a type of benign brain tumor, in 1999. Then, last year, his wife Michele was also diagnosed with an acoustic neuroma, and his sister Angela was diagnosed with glioblastoma, an aggressive brain tumor.

As his sister's health began to decline, Lupiano began wondering if there was a connection between their tumors. Through an investigation, he found more than 100 primary brain tumor diagnoses—about half that were cancerous—among students and faculty members at Colonia High School, his alma mater, between 1975 and 2000.

After Lupiano posted his findings online, John McCormac, mayor of Woodbridge Township where the school is located, reached out to offer his help. Currently, the township has hired an environmental engineering firm to test the school and the areas around it for possible contaminants.

According to McCormac, the firm is using Geiger counters, which detect nuclear radiation, "to scan every square inch of the property" and has placed radon detectors in all areas of the school, including classrooms, offices, and the gym. Tests are expected to be done in the next few weeks, Today reports.

"If we can enrich science by showing that an unknown compound is in high concentration and link it to primary brain tumors, maybe we can protect others, remove it from our environment to make sure it never happens again," Lupiano said.

Both the New Jersey Department of Health and Department of Environmental Protection have said they are "partnering with Mayor McCormac and Woodbridge Township to better understand the issue and determine whether any relevant environmental exposure concerns are present at the site."

"If there are any potential environmental exposure pathways identified and a need for further environmental sampling, the state Health Department will work cooperatively with [CDC's Agency for Toxic Substances and Disease Registry] to conduct a public health assessment and evaluate the potential for health effects," the departments added.

What does it take to prove a cancer cluster?

Although the number of cases among former Colonia High students and faculty may be high, it has not yet been confirmed a true cancer cluster. According to the National Cancer Institute (NCI), a cancer cluster is "the occurrence of a greater than expected number of cancer cases among a group of people in a defined geographic area over a specific time period."

To determine if the cases in New Jersey constitute a cancer cluster, the group will need to be compared with a control group elsewhere to see if cancer rates are higher than expected in the population over a certain 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," said Michael Gochfeld, a professor emeritus at Rutgers University's Environmental and Occupational Health Sciences Institute. "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."

However, even if these cases are determined to be a cancer cluster, proving a specific cause will likely be extremely difficult. According to a review of 576 cancer cluster investigations over 20 years, only 72 were found to have increased rates of cancer. Of those cases, only three were linked to potential exposure to cancerous materials, and only one of those had a clear, identifiable cause.

"You'll often find contaminants that are in the environment," said Peter Shields, the deputy director of the Ohio State University Comprehensive Cancer Center. "These low-level contaminations can be very difficult to prove as a cancer cluster because there are going to be a lot of other schools with the same level of contamination there, [and] they have don't brain cancers."

For his part, Lupiano said he believes the Colonia High cases may be attributable to the nearby Middlesex Sampling Plant. Between the 1940s and 1960s, the plant processed uranium ore, and while it was remediated, some of the sediment may have been brought to the high school when it was built in 1967.

And even if radiation is not the cause, Lupiano said there are other tests that can be done to find a contributing factor. "This is only the tip of the iceberg," he said. "This is only one of many, many tests that can be performed. Frequently, in hazmat, you never find it in the first shot." (Thompson, NBC New York, 4/19; Sudhakar, FOX News, 4/19; Holohan, Today, 4/20; Fiore, MedPage Today, 4/22)