Rise in cancer rate was real, study found
'Iexpected one thing and found something else," says Gilbert Welch, M.D., M.P.H. He's talking about a study he recently published that confirmed the rapid rise of a deadly but very rare cancer, esophageal adenocarcinoma. From 1975 to 2001, the incidence of this glandular cancer increased sixfold in the United States-from 4 to 23 cases per million. This got Welch's attention.
Detect: "Whenever the number of new cancers is growing quite rapidly," says Welch, "I ask the question 'Is there a change in diagnostic practice?' " An internist on the DMS faculty, he is the author of Should I Be Tested for Cancer? Maybe Not and Here's Why. His research focuses on problems created by efforts to detect disease early and by expansions in the definition of diseases. Whenever doctors screen more intensively for disease or widen the parameters for defining a disease, they find more of it, he explains. Welch suspected that the rise in esophageal adenocarcinoma was the result of a change in diagnostic capabilities. "In the last 20 years, the use of endoscopy-that flexible tube that we pass into the mouth, down the esophagus, into the stomach- has grown exponentially," he points out.
To test this hypothesis, Welch and Heiko Pohl, M.D., a gastroenterology fellow, compared the number of new cases of esophageal adenocarcinoma with the number of deaths from the cancer, per million Americans.
"If it's real cancer, and it's really increasing," says Welch, "you'd expect death rates to rise." And that's exactly what the research team found. The number of new cases and the number of deaths from the cancer are increasing at nearly the same rate. Between 1975 and 2001, deaths from esophageal adenocarcinoma increased sevenfold, from 2 to 15 deaths per million. "Conclusion: The rising incidence of esophageal adenocarcinoma represents a real increase in disease burden," Pohl and Welch wrote in their article, which was published in the Journal of the National Cancer Institute.
Discover: Not knowing what you're going to discover in a study "is what makes research interesting," says Welch. "You may have an idea, and it may be right or it may not be. Here, either answer was interesting to me." Welch says that he doesn't plan to do any further studies of esophageal adenocarcinoma, but he hopes that others will. It's still a very rare cancer, he emphasizes, but even so "we should be trying to understand why it could possibly be going up so fast."
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