ATLANTA - Uninsured cancer patients are nearly twice as likely to die within five years as those with private coverage, according to the first national study of its kind.

People without health insurance are less likely to get recommended cancer screening tests, the study also found, confirming earlier research. And when these patients finally do get diagnosed, their cancer is likely to have spread.

Experts said the research, conducted by scientists with the American Cancer Society and published in Cancer, the organization's medical journal, offers important context for the national discussion about health-care reform - even though the uninsured are believed to account for a fraction of cancer deaths.

In an accompanying editorial, the society's president repeated the organization's call for action to fix holes in the health-care safety net.

"The truth is that our national reluctance to face these facts is condemning thousands of people to die from cancer each year," Elmer Huerta wrote.

Hard numbers linking insurance status and cancer deaths are scarce, in part because death certificates don't have an insurance category.

The Associated Press estimated that 20,000 cancer deaths, about 4 percent of the total, are of uninsured people. Experts said that estimate - based on an analysis of hospital cancer deaths in 2005 gathered by the U.S. Agency for Healthcare Research and Quality information and other data - sounded reasonable.

"Insurance makes a big difference in how early you are detecting disease," said Ken Thorpe, an Emory University health policy researcher.

In the new study, researchers analyzed information from 1,500 U.S. hospitals that provide cancer care. They focused on nearly 600,000 adults under age 65 who first appeared in the database in 1999 and 2000 and who had either no insurance, private insurance or Medicaid.

They then checked records for those patients for the five years following. They found that those who were uninsured were 1.6 times more likely to die in five years than those with private insurance.

More specifically, 35 percent of uninsured patients had died at the end of five years, compared with 23 percent of privately insured patients.