Americans with colon and rectal cancers may get better care when states expand access to health insurance, a new study suggests.

In Massachusetts, after the state expanded access to health insurance, patients with these cancers were more likely than patients in other states to get needed surgery and to get it before their condition grew dire, the study found.

The study "provides cautiously optimistic evidence that expanding insurance doesn't just increase access to healthcare but also increases the receipt of care and optimal care for a common cancer," said lead author Dr. Andrew Loehrer, who worked on the study while at the Codman Center for Clinical Effectiveness in Surgery at Massachusetts General Hospital in Boston.

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In 2006, under then-governor Mitt Romney, Massachusetts overhauled its healthcare system by expanding access to Medicaid, the state and federal insurance for the poor. The state also created a new insurance program for people not eligible for Medicaid and required all residents to be covered by a plan.

The overhaul was a model for the national 2010 Affordable Care Act (ACA), which created insurance marketplaces in each state, mandated coverage and encouraged states to expand their Medicaid programs. There are currently 19 states that haven't expanded Medicaid access, however.

"As 19 states have yet to expand Medicaid in a similar way that Massachusetts has, evaluating the impact of that on a very common and deadly cancer remains important," said Loehrer, who is now at MD Anderson Cancer Center in Houston, Texas.

Colorectal cancer is the third most common cancer for both sexes and the second leading cause of cancer death in the U.S., according to the Centers for Disease Control and Prevention.

For the new study, the researchers compared hospital data collected from 2001 through 2011 on 17,499 colon cancer patients in Massachusetts and 144,253 more patients in New York, New Jersey and Florida - three states that didn't expand insurance access during that time.

Compared to colon cancer patients in the states without expanded insurance access, the patients with government-subsidized insurance or self-pay insurance in Massachusetts after the expansion had a 44 percent increase in surgeries to remove the cancer.

"I certainly cannot say with this study that the insurance expansion increased survival from cancer," Loehrer said. "What I can say is it was associated with an increase in surgery, and we know that surgery plays an important role in survival."

Additionally, the researchers report in the Journal of Clinical Oncology, after the Massachusetts law took effect, there was a roughly 6 percentage point decrease in the likelihood that colon cancer patients would need emergency surgery as well as an 8 percentage point increase in the probability that their surgery could be planned in advance.

"Colon cancer is an important test case," Dr. Benjamin Sommers, of the Harvard T.H. Chan School of Public Health in Boston, told Reuters Health.

The study looked at a very specific condition that may be responsive to more timely care and found people are more likely to get the treatment they need after insurance expansion, said Sommers, who was not involved with the new study.

It's difficult to know how the results apply to other states, he said, because Massachusetts is a high-income state with a lot of doctors. While many states that expanded Medicaid under the ACA aren't in the same position, those states likely have an even greater need for expanded coverage.

It's hard to know which of those effects - Massachusetts' larger number of doctors, or other states' need for broadened access to care - will be bigger, he said.