Medicare spends more than $1 billion each year for breast cancer screenings such as mammography, according to a new study.

However, all that expenditure may not help produce better results for older women, said Cary Gross, M.D., an associate professor of internal medicine at Yale University School of Medicine. He also directs the Yale Cancer Outcomes, Public Policy, and Effectiveness Research Center.

In the new study, Dr. Gross and his colleagues identified more than 137,000 women, aged 66 to 100, who had no history of breast cancer. Dr. Gross looked at the costs to fee-for-service Medicare for breast cancer screening during 2006-2007.

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The study authors also looked at costs of screening in different regions.

Women living in areas with higher screening costs were as much as 78 percent more likely to be diagnosed with early-stage or in-situ breast cancer as women in regions spending less.

However, regardless of how much was spent on screening, it didn't make a difference in diagnosing late-stage cancers, the investigators found.

This suggests "overdiagnosis" of breast cancers in the regions spending the most on screening, Dr. Gross said. This means a cancer that was diagnosed may not have been problematic during a woman's lifetime. However, other experts argue that it's difficult to determine which cancers will become a threat to health.

The study is published online in the journal JAMA Internal Medicine.

The variation in screening costs by regions, Dr. Gross said, is driven by newer and more expensive screening technologies such as digital mammography and computer-aided detection. The costs varied greatly by region of the country, from $42 to $107 per person.

In older women, he said, research is lacking about whether the newer technologies produce better health outcomes.

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The overall screening costs of a billion dollars annually are higher than previous researchers have found, Dr. Gross noted. He takes issue with Medicare's reimbursement strategy, which the study authors pointed out, "support rapid adoption of newer modalities [methods], frequently without adequate data to support their use."

"Our study is largely directed at policymakers," Dr. Gross said. For older women, he explained, the take-home message is this: "Getting more expensive tests for breast cancer does not necessarily produce a better outcome."

And he added, "Our study highlights the insanity of a system that pays substantially more for a new technology without any evidence that it is beneficial in the older population."

The co-author of an editorial accompanying the study, Jeanne Mandelblatt, M.D., a professor of medicine and associate director of population sciences at the Georgetown Lombardi Comprehensive Cancer Center in Washington, D.C., said that the new study "is a call to action to get more research."

The findings, Dr. Mandelblatt said, raise the possibility that newer technology may not always be better for all women. Research on the breast cancer screening technologies in older women is lacking "because older women have not been included in sufficient numbers" in research studies, she said.

"One important message for older women is they need to get involved in research studies, they need to advocate for research studies," Dr. Mandelblatt said.

Another expert, Judith Malmgren, takes issue with the findings and the emphasis on late-stage cancer detection.

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"By focusing only on stage 4, you are not evaluating the overall effectiveness of screening," said Malmgren, an affiliate faculty member with the department of epidemiology at the University of Washington School of Public Health, who has written about breast cancer screening.

"The purpose of mammography screening is to find early stage cancers," Malmgren said.