A cancer patient is seen through the tube of a magnetic resonance imaging scanner as she prepares to enter the MRI machine for an examination at Georgetown University Hospital in Washington May 23, 2007. REUTERS/Jim Bourg

Fewer than half of all Americans trust that their health insurance plans would pay for the full costs of cancer treatment and nearly two-thirds falsely believe Medicare would not pay anything, according to a survey released on Wednesday.

Nearly 70 percent of more than 1,000 adults surveyed said they were very concerned about paying for cancer treatments if they were diagnosed and 59 percent fear they would leave their families in debt.

The survey, published by the Community Oncology Alliance, suggests Americans are both worried and misinformed about the state of the U.S. healthcare system and changes that might be made as Congress and the White House work to reform the system.

And people rightly fear the expense of paying to treat cancer, the second-leading killer of Americans after heart disease, said Dr. Patrick Cobb, president of the alliance and a managing partner of Hematology-Oncology Centers of the Northern Rockies in Billings, Montana.

Few private insurance plans pay the full cost of cancer treatment, which can run $5,000 a month and more, and Medicare without supplemental coverage pays for 80 percent of the cost, leaving patients to cover the remaining 20 percent themselves or find other coverage.

Monthly out-of-pocket costs for cancer care and treatment, not covered by private insurance plans or Medicare, can easily run to $1,000 or more, Cobb said in a statement.

For many cancer patients, the costs of diagnostic imaging, surgery and expensive cancer medications, especially in the first few months of treatment, can add up to well beyond $2,500 per month.

The telephone survey of 1,022 adults by Opinion Research Corporation found close to 80 percent said they had known a relative or friend with cancer.

Just 45 percent said they believed their private insurance plans would cover the full cost of cancer treatment, while only 25 percent thought Medicare, the federal health insurance plan for the elderly, would cover the full treatment costs. Sixty-four percent wrongly said Medicare would not cover any costs.

And 33 percent said they would stop cancer treatment if it started getting too expensive.

Though the U.S. has the best cancer care delivery system in the world, the system is now in first-stage crisis because Medicare has substantially cut payments for cancer drugs and essential services, Cobb said.

Oncologists are spending an inordinate amount of time dealing with patient financial issues, including trying to find ways of navigating the insurance maze and identifying drug and co-payment assistance for patients in need, he added.

Most of those surveyed -- 85 percent -- said they believed a government-run health plan would have significant disadvantages for cancer care, compared to their own private insurance plans.

Close to three-quarters said it would mean higher taxes, 62 percent worried about longer waits for care and 56 percent thought the quality of care in general would fall.

President Barack Obama has started pressing for a public insurance option to be offered alongside traditional private, employer-sponsored insurance.

But opponents, including many Republicans in Congress, say a public plan would undermine the private plans and some groups have been running advertising campaigns about the issue.