Experts Call for Redefinition of 'Cancer'
Many growths are slow to progress and nonlethal, only leading to unnecessary treatment, panel says
By E.J. Mundell
TUESDAY, July 30 (HealthDay News) -- A panel of experts commissioned by the U.S. National Cancer Institute says that the word "cancer" may need to be redefined to prevent overdiagnosis and overtreatment of conditions that are often not lethal.
Writing in the July 29 online edition of the Journal of the American Medical Association, the experts say that widespread cancer screening programs turn up too many growths that would not progress to a lethal stage and are considered "indolent."
Most patients do not understand that distinction, however, and "the word 'cancer' often invokes the specter of an inexorably lethal process," wrote Dr. Laura Esserman of the University of California, San Francisco, Dr. Ian Thompson Jr. of the University of Texas Health Science Center at San Antonio, and Dr. Brian Reid of the Fred Hutchinson Cancer Research Institute in Seattle.
Cancer can take "multiple pathways," the three say, "not all of which progress to metastases and death, and include indolent disease that causes no harm during the patient's lifetime."
This re-examination of what constitutes a cancer diagnosis has been spurred by the explosion over the past few decades of sophisticated screening measures such as the mammogram, colonoscopy and the PSA blood test (for prostate cancer). All were heralded as potentially lifesaving, and many predicted that widespread adoption of these tests would catch disease early and cause cancer rates to fall.
But the cancer screening story has turned out differently, the panel noted, because many of the lesions picked up on screening have turned out to be indolent.
"Screening for breast cancer and prostate cancer appears to detect more cancers that are potentially clinically insignificant," the experts said. The same might be said for screens for thyroid cancers and melanomas -- certainly, lives have been saved because tumors were detected and treated, but "the detection of indolent disease" has risen, too, the panelists wrote.
Issues like this have played out in recent years. The United States Preventive Services Task Force, an influential government panel, caused a furor in 2009 when it called for the abandonment of regular mammography screening for women under 50, reasoning that the benefits of screening for younger women were outweighed by the risks. The same panel also rejected the widespread use of the PSA test, noting that it too often picked up slow-growing lesions that might never harm men's health.
According to the experts writing in JAMA, the best-case scenario for cancer screening is when the tumor is slow-growing but also typically progressive. Colon cancer often acts in this way, the team noted, and colonoscopy has become an "effective" screening program.
In the meantime, however, "overdiagnosis" occurs. The experts say a redefinition of cancer may be needed to quell patient fears over indolent lesions and curb overdiagnosis and overtreatment.