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To screen or not to screen

November 21, 2012|By Monte Morin
  • A radiologist uses a magnifying glass to check mammograms for breast cancer.
A radiologist uses a magnifying glass to check mammograms for breast cancer. (Associated Press )

A controversial study published in the New England Journal of Medicine that raises questions about the value of routine mammogram screenings is just the latest in a series of papers raising alarms over some forms of cancer treatment.

Earlier this year, another study concluded that most patients diagnosed with early-stage prostate cancer will live just as long if they simply watch their cancers rather than have them surgically removed. 

At the root of both studies is a newly developing view of early cancer diagnosis, particularly for prostate and breast cancer. Some epidemiologists and biostatisticians like Dr. Donald Berry of the MD Anderson Cancer Center in Houston and Dr. H. Gilbert Welch of  Dartmouth's Geisel School of Medicine, argue that broad-based screening has resulted in over-diagnosis of cancer.

The problem, they say, is that some early cancers develop into large malignant tumors, while others regress and never become a problem. While these small initial clusters of cells once escaped the notice of doctors, they are now detected by sophisticated screening.

"The problem is that we do not yet understand the biology of cancer well enough to know which cancers are important to find early and which can be ignored," Berry wrote in the Journal of the National Cancer Institute.

Their position, however, is by no means universal. Some doctors have roundly criticized their statistics-based research, calling it unscientific, because it does not rely on randomized trials.

Dr. Daniel Kopans, a senior breast imager at Massachusetts General Hospital in Boston, has accused Welch and others of targeting screening as a means of reducing healthcare costs.

Kopans says talk of "fake" cancers is "simply malicious nonsense."

"Mammography does not cause 'over-diagnosis,' " Kopans said. "Unfortunately, pathologists are not yet able to distinguish cancers that will be lethal if left untreated from those that do not need treatment."

Still, the idea that screening is not a silver bullet, particularly when fighting breast cancer, has many adherents.

"Early detection is a really nice message -- it makes you feel in control," said Dr. Susan Love, an oncologist and the head of the Susan Love Research Center in Santa Monica. "But it doesn't address our current understanding of how cancer works."

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