Cancer Clusters

What exactly is a cancer cluster? A cancer cluster is when there is a geographic area with a statistically higher than average occurrence of cancer among its residents.

More than 1,000 suspected cancer clusters are reported to state health departments every year.

News reports on cancer clusters can be alarming. I read about a possible cancer cluster associated with a high school in New Jersey. The reports said that more than 100 former students, teachers, and staff members had been diagnosed with cancer over a 30-year span. Not many days later, another cancer cluster question hit the news: a former Phillies baseball pitcher had died of brain cancer, the sixth ex-team member to die of the same diagnosis since 2003.

Some of you may be familiar with the Silent Spring Institute in Newton, MA. Founded in 1994, their website describes them as a scientific research organization dedicated to uncovering the links between chemicals in our everyday environment and women’s health, with a focus on breast cancer. Much of their work has been on Cape Cod where there have been higher than expected rates of breast cancer.

Some of us remember Anderson vs. W.R. Grace and Company, a lawsuit that garnered national attention in 1994. The contention was that toxic waste dumped by two factories in the 1960s and 1970s contaminated the Woburn water supply and caused five leukemia deaths, three nonfatal cases of leukemia, and several other serious illnesses in the community. Children were being diagnosed with leukemia at rates as high as eight times the national average.

The case was eventually settled out of court with W.R. Grace paying eight million dollars to the families. This case became a popular book and movie called A Civil Action.

There are many other examples of suspected environmental contaminants and of cancer clusters. In fact, more than 1,000 suspected cancer clusters are reported to state health departments every year. It is very difficult to confirm any of these suspicions.

Unfortunately, cancer is not rare. It is estimated that 40% of Americans will be diagnosed with some kind of cancer during their lifetimes. When we, or someone close to us, is part of that statistic, we begin to pay closer attention. It may be especially alarming if we hear of multiple diagnoses of the same kind of cancer—even if the numbers actually are in line with epidemiologists’ projections.

Think of the phenomenon that regularly occurs when we buy a new car. All of a sudden, we see many cars of the same make and model on the highway. They must have been there all along, but we didn’t notice. This is not so different as becoming more aware of cancer.

When a suspected cancer cluster is reported, there is a formal series of explorations and research questions that must be answered. Some suspicions are more likely than others to meet the criteria of a cancer cluster. If the reported cancers are of a rare type or occurring in an unusual group of people, that is more worrisome.

As an opposing example, we know that breast cancers are not uncommon among older women. A higher than usual incidence of breast cancer in an area with many retirees would not be alarming. According to the CDC, most investigations of reported cancer clusters are closed after an initial look.

Most of us would like to be able to identify the reason we had cancer. There are many possible environmental risks that, as tempting as it is to label them the culprits, it is close to impossible to separate them out and draw conclusions. Cancer risk often is associated with lifetimes of exposures as well as predisposing genetic factors.

We also know that we are the most vulnerable to exposure when we are in-utero or during adolescence—times when growth is happening quickly. There isn’t much we can do about what happened then; no amount of sunscreen now can make up for lying on the beach, coated in baby oil, and using a reflector. Of course, that is not to say that we should not use sunscreen now to prevent any further damage and reduce the possibility of skin cancers.

The summary here seems to be that it certainly is possible that environmental toxins that are very prevalent in a particular community may result in more cancer cases than otherwise would have happened. However, it is also likely that most of us will never have the answer to our question of “Why did this happen to me?”