Cancer patients insured by California’s health plan for low-income people are less likely to get recommended treatment and also have lower survival rates than patients with other types of insurance, according to a new study by University of California-Davis researchers.

While other studies have linked Medicaid insurance status to worse cancer outcomes, the UC-Davis study appears to be the first to examine the impact of various kinds of health insurance across more than one kind of cancer.

Understanding how well Medicaid (called Medi-Cal in California) serves cancer patients is crucial, experts say, because as much as 10 percent of California’s Medicaid expenditures go to cancer care. And Medi-Cal has grown to cover more than 12 million Californians – nearly a third of the state’s population.

“What’s striking is how similar the findings were for Medi-Cal members and the uninsured,” said Dr. Kenneth Kizer, director of the UC Davis’ Institute for Population Health Improvement, which conducted the study. “If we weren’t spending billions of Medi-Cal dollars on cancer care perhaps that would not be surprising, but you’d think that the outcomes might be better when you’re spending that much money.”

The UC Davis researchers used California Cancer Registry data to study the experiences of approximately 700,000 Californians diagnosed with breast, colon, rectal, lung, and prostate cancer between 2004 and 2012. They tracked how early these patients were diagnosed, their quality of treatment and their five-year relative survival rates according to their type of insurance. The types were Medi-Cal, Medicare, dual Medi-Cal/Medicare (for lowest-income seniors), private insurance, Department of Defense (DOD) insurance and Department of Veterans Affairs (VA) insurance.

Among the findings:

* Medi-Cal patients were diagnosed with advanced (stage IV) prostate cancer more than three times as often as patients with private insurance or DOD coverage.

* Medi-Cal patients with breast, colon or rectal cancer were more likely to be diagnosed at an advanced stage and to have worse five-year survival rates than people with other types of insurance.

• Low-income seniors covered by Medicare and Medi-Cal, known as “dual-eligible patients,” were the least likely to receive recommended treatment for breast and colon cancer.
• VA patients waited the longest to be treated for breast, colon, rectal, lung and prostate cancers, but their outcomes compared favorably to patients with other types of health insurance and they were generally more likely to receive recommended treatment.

What researchers still don’t know, Kizer said, is the reason for these disparities. It’s possible that Medi-Cal patients drop on and off the rolls, missing preventive screenings that could help detect cancers earlier. Audits and studies also have shown that some of the state’s Medi-Cal patients have difficulty getting access to doctors and specialists.

Researchers also can’t explain why Medi-Cal patients are less likely than patients with other kinds of insurance to receive recommended treatment after they are diagnosed. And they also don’t know whether cancer patients fare better or worse in Medi-Cal managed care programs, which now cover most of California’s Medicaid population.

“It’s not acceptable to have these variations” based on insurance coverage, particularly regarding breast and colon cancers for which preventive screenings are well-established and effective, said Christina Clarke, a research scientist at the Cancer Prevention Institute of California and a consulting associate professor at the Stanford University School of Medicine. She was not involved in the study.

“What’s particularly poignant is that we’re seeing these big disparate outcomes among groups in cancers where we have strong playbooks. That’s the tragic thing here,” Clarke said. “There’s a body count and we’d like to figure out a better way to insure that all Californians are getting the recommended screening for these deadly cancers and treatment according to guidelines. We have a lot of work to do.”