I-Team: Cancer clusters, while not rare, are difficult to prove
KALAMAZOO, Mich. —
The American Cancer Society estimates 58,360 Michiganders will be diagnosed with cancer this year and an estimated 21,150 people will die because of the disease.
The ghosts of Michigan’s industrial past haunt communities around the state with toxic pollution found in our air, water, and soil.
Heightened awareness of contaminants in the environment have raised concerns about possible cancer clusters.
Defined by researchers 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,” cancer clusters are notoriously difficult to prove.
Nationwide, more than 1,000 suspected clusters are reported to health officials each year. According to the American Cancer Society four out of five investigations fail to meet the criteria of a true cancer cluster.
An epidemiologist with the Michigan Department of Health and Human Services, Laura Abington is in the process of conducting about half a dozen cancer incident assessments around the state, including in Parchment, Michigan.
“It is generating phone calls and I do hear citizen concerns over their cancer and why they may have it and all that,” Abington said.
More communities are already in line to find out if cancer rates in their areas should be investigated as a possible cancer cluster.
“Rates in some areas are higher and some areas are lower and they fluctuate throughout time. So we just generally see these sorts of fluctuations,” Abington said.
An oncologist at the West Michigan Cancer Center, Dr. Iman Mohamed said cancer clusters are not rare, just incredibly difficult to prove.
“People need to think of smarter, cleaner ways of preserving whatever we dump into our systems because it's possible some permanent damage to the baby forming cells would result in future cases of cancer,” Mohamed said.
The vast majority of cancer cases are not inherited, she added. “Most of it is lifestyle,” Mohamed said. “They eat fast food, their weights are high, add to that cigarettes, all the things we add to our systems. So it’s lifestyle.”
State health officials said cancer investigations can find association but rarely identify causation, particularly in communities.
“In just general population studies where everybody leads different lifestyles, different backgrounds, different exposures, finding an explanation, if there is an increase in cancer, is especially difficult,” Abington said.
Michigan’s cancer registry records a person's address at the time of diagnosis, not where he or she grew up or lived previously.
“Residential history is challenging, so is the latency period of cancer; cancer could develop decades after an exposure occurred,” Abington said.
A state cancer incident assessment in 2018 found nothing out of the ordinary in Otsego, Michigan, where current and former residents continue to voice concerns about a possible cluster.
The latest round of private well testing overturned previous results that showed levels of PFAs and dioxins. The Michigan Department of Environmental Quality determined “equipment used by the contract lab in Houston was contaminated,” and the most recent testing at a different lab found the water is safe to drink.
The DEQ is now testing soil samples in Otsego and those results are expected to be released in three to four months. Depending on what’s found there, state health officials could revisit Otsego to conduct another assessment.
Meanwhile, the Justice for Otsego Group is raising money to conduct its own tests in the hope of finding answers and exercising any ghosts of the past.
Mohamed said concerns about environmental contaminants need to be investigated; however, she added, “We need to also put this into perspective, we're talking about a disease that's fairly common.”
According to the American Cancer Society, nearly one-third of all people in the United States will develop cancer during their lifetimes, and people are living longer.
The latest numbers from the state show 53,541 people were diagnosed with cancer in Michigan in 2015 and 20,959 people died in 2016 because of the disease.
Although it appears the numbers are on the rise, doctors are quick to note the aging baby boomer population and overall population growth along with long life expectancies can skew statistics. The age-adjusted cancer rates in Michigan are down to some of the lowest levels the state has seen in decades.