Overdiagnosis of cancer focus of review

An analysis of cancer diagnosis in the past 30 years related to mortality and screening for the disease shows that overdiagnosis of cancer should become a focus of the medical community. Researchers H. Gilbert Welch, M.D. and William Black, M.D., of the Dept. of Veterans Affairs Medical Center, White River Junction, Vt. and the Dartmouth-Hitchcock Medical Center conducted a review, finding that many cancers are diagnosed that would never require treatment.

Following a systematic review, the researchers learned that though cancer diagnosis has increased, there has been no association with mortality to account for the rising numbers. Overdiagnosis of cancer occurs from sophisticated screening tools that the researchers say could cause harm to some individuals.

The study authors write, "Whereas early detection may well help some, it undoubtedly hurts others. Often the decision about whether or not to pursue early cancer detection involves a delicate balance between benefits and harms…different individuals, even in the same situation, might reasonably make different choices."

The scientists hope to bring focus to the issue that many cancers that would never cause symptoms are overdiagnosed. CT, MRI, colonoscopy and other screening tools may be leading to insignificant reporting of cancers.

Breast cancer and prostate cancer - through mammograms and PSA testing - could be responsible for 25 and 60 percent of overdiagnosis of cancer respectively.

Patients undergoing early cancer screening tests should be advised of the potential for overdiagnosis suggest the researchers. Another way to prevent reporting of insignificant cancer findings might be to raise the threshold of reporting small tumors or incidental findings associated with cancer screening.

"It is possible that new insights from genomics will ultimately allow us to more accurately predict tumor behavior at the individual level," the authors write. "However the field has not advanced to that point yet. We must explore other clinical strategies."

Overdiagnosis of cancer can result in harm, and is the focus of the recent review. The scientists looked at five types of cancer - thyroid, prostate, kidney and breast cancer, and melanoma - finding that more cancer cases have been reported, but there has been no increase in mortality, possibly from overdiagnosis of cancer.