Defining the Elusive Cancer Cluster
By Ann Miller Baker
What is a Cancer Cluster?
And Who Is Responsible for Investigating?
It’s a more common fear than you might realize.
More than 1,000 suspected cancer clusters are reported to public health agencies across the nation each year. But what exactly is a cancer cluster — and who is responsible for investigating?
The U.S. Centers for Disease Control and Prevention (CDC) defines a cancer cluster as: A greater-than-expected number of cancer cases that occurs within a group of people in a defined geographic area over a period of time. Each element of that definition includes criteria that must be met before a group of cancer cases can be considered a cluster:
- A greater-than-expected number occurs when the observed number of cases is higher than one would typically see in a similar setting (a group of people with similar age, gender, race, etc.).
- Of cancer cases — All of the cases must involve the same type of cancer, or types of cancer scientifically proven to have the same cause.
- That occurs within a group of people — The cancers are occurring in a carefully defined population, which may include factors such as race, ethnicity, age or gender.
- In a geographic area —The boundaries must be defined carefully. It’s possible to “create” or “obscure” a cluster by selection of a specific area.
- Over a period of time — The time period over which the cases occurred.
Obviously, meeting each of these specific criteria requires a level of expertise, time and money. People who suspect a cancer cluster usually turn first to their local public health department. But the responsibility ultimately rolls up to the state department of health. The Florida Department of Health uses 2013 Cancer Cluster Guidelines from the CDC to determine cancer clusters.
The state health department also outlined the steps taken in a cluster investigation in a 2016 publication, “Cancer Cluster Investigations — When exposure to environmental contaminants is suspected.” There are many steps, and the agency reviews information as each step is completed to decide whether or not to move on to the next step.
For cancer cluster sleuth Cheryl Jozsa, just getting to the first step has been a 15-year struggle. “It’s really frustrating,” Jozsa said. “For the average person looking for answers, it’s a matter of trial and error. Perhaps there would be more cancer clusters under investigation if the system didn’t make it so hard.”
Her personal investigation of a possible cancer cluster began in 2003, after leukemia claimed the life of her sister Terri. Jozsa found out that four of Terri’s 235 classmates in Manatee County’s Bayshore High School class of 1979 also had developed leukemia. Another three developed ALS, an autoimmune disorder more commonly known as Lou Gehrig’s disease. Of those seven, only two are still alive today.
Though the school they attended has been torn down and rebuilt on an adjacent site, Jozsa has long suspected the old school’s water might have been contaminated by a nearby business. Despite ownership changes, the property has been the subject of multiple court orders from Florida’s Department of Environmental Regulation to clean up the site. Efforts are still ongoing.
Jozsa has brought her concerns to the Manatee County School Board more than once over the years. The board maintains that soil tests near the old school site have repeatedly turned up negative for contaminants.
Jozsa said she realizes it’s impossible to go back and look at what was in the water and soil near Bayshore High School in 1979. But she also notes that in 1989, suspected toxins were reported in test wells near an underground storage tank housed on the campus of a vocational/technical school adjacent to the old Bayshore High site. She said these same toxins are appearing in soil and water samples to this very day.
When Manatee County commissioners and school board members met in May 2017 to discuss future land use issues for that property, Jozsa and her supporters were able to speak about their cancer concerns. They convinced commissioners to direct the Manatee County Department of Health to initiate data collection on the possible cancer cluster.
Manatee DOH has posted newspaper notices and sent letters to Bayshore graduates from 1985 to date, looking for any cancer cases. Autoimmune disorder rates questioned by Jozsa are not part of the data gathering efforts. The fact-finding portion of the Manatee DOH investigation closed March 28, 2018.
So far, no one from the state or county has asked to see any of Jozsa’s data.
While Jozsa and her colleagues await the county’s report, state health department publications plainly attempt to limit expectations of any such investigation. The 2016 Cancer Cluster publication states:
“A cancer cluster may be due to chance alone, like the clustering of balls on a pool table… Finding an exact cause is very hard to do. Follow-up studies may take years to complete. They often take a great deal of research and money with no cause ever pinpointed.
Every year, groups of people report more than a thousand potential cancer clusters to public health agencies across the nation. Of these, most do not meet the guidelines for investigation as a cancer cluster. Of those that do, 5 to 15 percent of studies may confirm that the number of cases of a certain cancer exceeds what is expected. Even then, in most cases, science cannot pinpoint a cause.”
That won’t stop Jozsa and her colleagues from continuing their quest. They intend to take the issue to Tallahassee and/ or Washington if need be. “We’re not looking for any lawsuits,” she said. “That won’t bring back those we’ve lost. But if these toxins are still in the ground, people need to know.”
This article is part of Moffitt Momentum® magazine, a publication that shares portraits of hope, innovation and triumph, all leading to the same end: beating cancer. Click here to access the full issue of the magazine in PDF format.