For all the controversy that surrounds it, mammography is the poster child for image-based screening. Lung, colon, and other cancer screening programs will need to approach breast screening's efficacy before they can become standard preventive care, screening leaders said at the RSNA meeting."Breast cancer screening has been around for a long time," said Dr. Ellen Mendelson of Northwestern University during a panel discussion on Friday. "It is a mature program."
Its years of practice have helped x-ray mammography iron out many of the kinks, including standardization and patient compliance, that newer screening modalities still face.
"We have, I think, convinced women that screening mammography is extremely important," Mendelson said.
Now, mammographers face problems of low reimbursement and rising demand and debate about the optimal time to begin screening. But consumers may not wait for science to dictate the best time, if any, to undergo screening for other cancers, according to Dr. Michael Brant-Zawadzki of Hoag Hospital in Newport Beach, CA. Graying baby boomers, the wellness movement, and an increased standard of living are among the factors fueling a trend toward self-referred screening and out-of-pocket payments.
Science doesn't yet support making newer screening tests, such as lung and colon CT, more widely available, said Dr. Denise Aberle of the University of California, Los Angeles. Lung imaging, for example, needs standardization in CT protocol and reliable, efficient, high-sensitivity reading.
"We desperately need software resources to help with computer-aided detection (CAD)," she said.
Colon cancer screening's barriers to viability come primarily in the form of efficacy and patient compliance, said Dr. Judith Yee of the University of California, San Francisco. Her vision of virtual colonoscopy's future included a prepless, more comfortable procedure and improved intravenous contrasts.
The possibility that screening will become more widely available also raises ethical questions, said Robert Smith, Ph.D, of the American Cancer Society.
"It is reasonable to say that we do better to find cancer early," he said.
Improving survival rates is not a simple cause-and-effect motivation behind increased screening, however. Simply finding a cancer early, but not early enough to decrease mortality rates, does not improve the efficacy of a particular screening method, Smith said. Radiologists must heed factors such as lead-time bias, length bias sampling, overdiagnosis, and selection bias when determining the efficacy of screening studies.
"We should encourage people to screen when we know the efficacy of the screening procedure, but we shouldn't gloss over the limitations," he said.
