Cancer Biomarkers: Too Many Tests, Too Few Cures
One researcher says many screening tests are more trouble than they are worth.
Aug. 13, 2010— -- Blood tests and imaging studies that find early signs of cancer -- often looking for cellular changes called biomarkers -- are usually reported in banner headlines, but in many cases these "markers" fail to deliver the promised early detection that could lead to a cure.
That was the message delivered in a blistering analysis from Canadian cancer researcher Dr. Eleftherios Diamandis in an opinion piece published by the Journal of the National Cancer Institute.
Diamandis, who works at Mount Sinai Hospital in Toronto, put it this way: "Press releases and news conferences that immediately accompany publication of a high-profile biomarker generate high expectations about the new biomarker." But when follow-up tests fail to confirm the original reports, there are no headlines.
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As a result, the public often beats a path to the doors of medical clinics seeking cancer tests that simply don't exist or are so flawed that they offer no useful information, he said.
Dr. Otis Brawley, chief medical officer at the American Cancer Society and himself a critic of over-selling cancer tests and screenings, applauded Dimandis for going on record with a criticism of the biomarker revolution.
Diamandis "makes an incredibly important point," Brawley, told MedPage Today in an email.
Even PSA (prostate-specific antigen) -- perhaps the most widely used cancer screening test -- remains controversial, Brawley said. While a number of cancer specialists -- and celebrities -- aggressively campaign for PSA screening, Brawley said that the test may eventually "prove useful but the jury is still out."
Biomarkers have undeniable cache, as the idea of a simple blood test or imaging study to rule in or out cancer is an easy sell to a cancer-wary public, but the downside of their use has real economic and medical consequences, Brawley warned.
"I am very worried that doctors and others have overpromised the power of screening and the public expects too much," Brawley said. That increases medical costs but also "prevents us from asking the right scientific questions that can ultimately improve health."
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