Nature Medicine | Spoonful of Medicine

Mammograms not all they’re cracked up to be?

mammogram2.jpgThe utility of regular breast cancer screening is again being questioned after a study published yesterday found that mammogram testing does not reduce the breast cancer death rate as much as once thought. Instead, it appears, increased awareness and improved treatments are mostly responsible for improved survival rates.

A team led by Mette Kalager from the Oslo University Hospital in Norway analyzed medical records from more than 40,000 middle-aged Norwegian women with breast cancer taken from both before and after the Scandinavian country started a breast-cancer screening program in 1996. Reporting in the New England Journal of Medicine yesterday, the researchers found that mammograms reduced the rate of death from breast cancer, but only by around 10% — significantly less than previous estimates of up to 25%.

The new findings add to a growing debate about whether annual or bi-annual mammograms are necessary and useful for women in the 40s and 50s in the modern era of more advanced breast cancer therapies and awareness.

“It is quite plausible that screening mammography was more effective in the past than it is now,” Gilbert Welsh, who studies cancer screening at Dartmouth Medical School in Hanover, New Hampshire, wrote in an accompanying editorial. “The increased awareness about the importance of promptly seeking care for overt breast abnormalities… and the widespread use of adjuvant therapy have probably combined to make screening now less important.”

But the most recent research is not without its flaws, medical experts say. The NEJM study only followed women for around two years after receiving mammograms, which some argue is not long enough to realize the full benefits of screening.

Perhaps the controversy over mammographic screening will be settled not by foregoing the technology, but by improving it. An advisory panel to the US Food and Drug Administration today is set to review a new three-dimensional mammography system that might be a better tool for finding breast tumors than conventional mammography alone. Adding the third dimension means exposing women to more radiation, but the company developing the system, Massachusetts-based Hologic, claims that the reduction from finding breast cancer earlier “greatly outweighs” any extra health risks.

Image: Rhoda Baer / National Cancer Institute

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