There are two major problems in cancer diagnosis, problems that seem paradoxically opposed. The first is under-diagnosis: colon cancer, breast cancer, cervical cancer, and many others are very curable if caught at an early stage, says Deborah Schrag, a medical oncologist at the Dana Farber Medical Institute. Despite advanced techniques to catch these cancers early, far too many patients die from these diseases because they are detected too late. At the same time, there is an exploding new problem of over-diagnosis, she says. Some types of cancer, especially breast and prostate cancer, will never progress to advanced disease. Yet these cancers that would not prove fatal are being treated, often with significant side effects to the patient. We definitely over-treat prostrate cancer in this country, says Harvard cell biologist Lewis Cantley.
The problem is doctors cannot tell the difference between fatal and non-fatal cases, which presents “an incredible clinical dilemma for people,” says Harold Varmus, the Director of National Cancer Institute. How can we discern between those cancers that will progress and those that will not? Varmus speculates that in the future we might be able to “take just a few cells from those early lesions and examine them genetically for other kinds of marks on the DNA that would predict whether or not this is a lesion which might never be able to progress.” It is also possible, though, that every early tumor has “some probability of expanding and invading and growing to become a medical problem,” he says. Understanding this will be crucial to future cancer diagnosis and treatment.
Until these more accurate diagnostic tools exist, it will just be a game of probability, says Varmus. And these two conflicting narratives of under-diagnosis and over-diagnosis—while both true—will continue to create enormous confusion on the part of the public. “It is tough to get these messages across—not only to the public but to physicians and clinicians too—because we don’t have the techniques…to figure out this is the one you have to pay attention to and we’ve got to deal with and this one we can let it sit,” says Schrag. “Cancer, just the word cancer, is still so terrifying that at the individual level people and physicians feel compelled to act and that is going to be a big challenge for us,” she adds.
—ABCNews: “Is Cancer Being Overdiagnosed?“
—2010 Study of Cancer Over-Diagnosis
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