Mapping Cancer: Promising legislation must be precise to be effective

Editorial Board By Editorial Board The Post-Standard
on July 11, 2008 at 5:02 AM, updated July 11, 2008 at 5:06 AM


Plotting cancer cases on maps makes a lot of sense.

It's a good way to spot clusters or unusually numerous occurrences of the disease that may have been brought on by environmental causes, like toxic chemicals seeping into groundwater. Once clusters are identified, steps can be taken to eliminate the threat.

But legislation that would require the state departments of Health and Environmental Conservation to create such maps for the public to see may fall short of what's needed to reach sound conclusions.

The bill leaves it up to the agencies to decide what specific information would be used to put the maps together. Unless they're based on comprehensive data, cancer maps generated under this proposed law could be highly misleading. People could get the false impression that they're in danger or, worse, that they're safe when they really are at risk.

Legislators should rethink the bill with an eye toward being more explicit about the information to be used and how it would be collected.

The bill, which was passed by both houses of the Legislature last month, requires the Health Department to gather the genetic history, occupational history, age and address history for each person in the state with a reported case of cancer. That's about as detailed as the bill gets.

The bill allows the department to collect other information it deems relevant and stipulates that, at a minimum, it must consider data it already collects for other purposes. That appears to include the millions of records in the state's cancer registry, which documents more than 100 different pieces of information on each person in the registry.

Limitations of the cancer registry, though, show how the mapping initiative could go awry without careful planning.

The registry, as comprehensive as it is, does not include records on all malignant cancers. Some skin cancers are left out because they're rarely fatal. That kind of reasoning could prove tragic if applied to cancer maps designed to alert the public to risks.

The American Cancer Society, too, points out that just because a half a dozen people with cancer live near a hazardous waste site doesn't necessarily mean that their cancers are related to what is in that dump. Cancer often has a long latency period; the real factors that triggered their diseases may have occurred 20 years earlier somewhere else. Any mapping effort must take that into account, along with lifestyle factors, like smoking and obesity.

More than 100,000 malignant cancers are diagnosed in New York every year. Cancer cluster maps could help lessen the toll somewhat, but only if they're based on exhaustive, epidemiological research.