A Cancer Cluster Is Tough to Prove

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marine with doctor_oncology news australia_800x500By George Johnson – NY Times.

Last month, thousands of Marines and their families were blocked in federal court from pursuing their claim that the government had given them cancer. The decision, involving people exposed to contaminated drinking water while stationed at Camp Lejeune, a base in North Carolina, didn’t consider the science.

Long before expert witnesses could be called to testify, a United States Court of Appeals let stand its earlier ruling that the lawsuit had come too late. It failed to meet the requirements of a state statute banning claims arising more than 10 years after the final occurrence of a harmful act.

The genetic mutations that cause cancer can take decades to manifest themselves, far longer than the North Carolina statute of repose allowed. But the laws we cobble together often trump those of science. And even when legal obstacles can be overcome, a link between a cancer and environmental pollutants is exceedingly difficult to establish, whether in a laboratory or a court of law.

In past investigations, only two residential cancer clusters in the country have been linked, though only weakly, to environmental toxins. Camp Lejeune has become the third.

The plaintiffs in the lawsuit lived at the base at various times from the 1950s through 1985, a period when the drinking water was polluted with dry-cleaning fluid, organic solvents and benzene — chemicals on the National Toxicology Program’s list of known and probable carcinogens.

Even so, epidemiological studies published last year by the Centers for Disease Control and Prevention found that Camp Lejeune’s rate of cancer mortality was lower than that of the general public — 1,078 cases among the Marines during a 10-year period, when 1,272 would have been expected in a population that size.

That would ordinarily seem to rule out a cancer cluster. Epidemiologists, however, suspected that the numbers might have been distorted by a “healthy soldier” or “healthy veteran” effect. The military and their kin may receive better medical care than most people, making them less likely to die prematurely from cancer. To allow for that possibility, cancer deaths at Camp Lejeune were compared with those at Camp Pendleton in Southern California, where there was no water contamination. It was then that hints of a problem appeared.

Over all, Marines who had served at Lejeune were 10 percent more likely to die from cancer than their counterparts at Pendleton. Deaths from kidney cancer, for example, were 35 percent more likely. Altogether, 16 of 21 types of cancer showed modest increases at Lejeune.

Most of these conditions are rare enough that the absolute number of excess deaths was low — 42 from kidney cancer, for example, when 36 was considered average. For multiple myeloma, the increased risk was razor thin: 17 deaths at Lejeune, when 16 would have been expected. (Similar results were found in a separate study involving the base’s civilians.)

The more unusual a cancer, the harder it is to separate genuine influences from statistical noise. Especially puzzling were some 80 Lejeune veterans who came forward with diagnoses of male breast cancer, some at an unusually early age. The annual incidence of this condition is about 1.4 cases per 100,000 men — about 1 percent of the rate for women.

Hundreds of thousands of men may have been exposed, for various lengths of time, to Camp Lejeune water. Whether that is enough to implicate the pollution is still under consideration…read more.

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The ONA Editor curates oncology news, views and reviews from Australia and around the world for our readers. In aggregated content, original sources will be acknowledged in the article footer.

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