The 2006 Massachusetts health overhaul didn't boost the state's mammography rates or lead to more breast cancers being caught early, despite rising insurance rates, new research shows.

Researchers had expected to see an increase in breast cancer screening as the number of insured women went up, because earlier work had suggested women without insurance were less likely to get mammograms.

"We were a bit disappointed that we didn't see any substantial changes," said Dr. Nancy Keating, of Harvard Medical School and Brigham and Women's Hospital in Boston, who led the work.

Massachusetts' health care reform was enacted in 2006, when Mitt Romney - Republican presidential candidate and now an opponent of President Obama's Affordable Care Act - was governor.

Fully implemented by 2008, the legislation required everyone in the state to have health insurance and made subsidized insurance available to residents who were uninsured or had limited coverage.

There are some signs that the reform has had a positive impact on public health, although not all studies have been encouraging. For instance, one report from last year said the number of emergency room visits at a dozen hospitals in the state had not fallen, despite expectations that better access to primary care would take pressure off ERs (see Reuters Health story of June 2, 2011).

Keating's results are based on state health surveys and data from cancer registries. Her team found that in 2006, 69.2 percent of Massachusetts women aged 41 through 64 reported having a mammogram in the previous year. In 2008, the number was 69.5 percent and in 2010, 69.0 percent.

Until the last few months of the study period, major medical organizations all recommended annual breast cancer screening starting at age 40. In November 2010, however, the government-backed U.S. Preventive Services Task Force began advising routine mammography every two years instead, and only for women ages 50 to 74.

The researchers also compared their results to mammography rates in California after adjusting statistically for different income levels, educational backgrounds, race and other variables.

In California, which had no health reform during the study, mammography rates went from 59 percent in 2006 to 56.2 percent in 2010, mirroring the trend seen in Massachusetts.

There were no signs that early detection was affected by the healthcare overhaul, either, according to the study, which was published in the journal Cancer.

Still, Keating told Reuters Health, "in retrospect we might have been able to anticipate that."

In 2006, only 6.4 percent of people in Massachusetts were uninsured. Even though that had dropped to less than two percent by 2010, only a small number of women would have gone from uninsured to insured, Keating said.

"I actually still believe that if we looked at this in Louisiana, where a quarter of people are uninsured, there would still be an effect," said Keating, adding that mammography rates were also high in her state to begin with.

"With the Affordable Care Act I would expect to see a difference, because in the rest of the U.S. we are starting out with a much lower rate of insurance and mammography," she said.

Mario Schootman, who has studied the effect of poverty on cancer screening rates, also emphasized that the conclusions from the new work are limited.

"Studies like the Keating one are becoming increasingly important as the (Affordable Care Act) is further implemented, potentially resulting in cost savings and improvements in public health," Schootman, of Washington University in St. Louis, Missouri, told Reuters Health by email. "Unfortunately, the Keating study does not provide a definitive answer to this question."

The study was published in journal Cancer.