ORLANDO, Fla. (AP) -- Adult survivors of childhood cancer who most need mammograms and other tests to watch for second cancers are less likely to follow screening recommendations than the general public or even their healthy siblings, a new study finds.

Less than half of the cancer survivors in the study received mammograms, colonoscopies or skin cancer screenings as often as recommended.

Cancer survivors are at higher risk of getting the disease again, because treatments like radiation raise this chance, and because of genetic factors that led to the disease in the first place.

Some people may avoid screening tests because they want to put the scary experience of having had cancer behind them.

However, "many survivors do not know the specific treatments they had," let alone what follow-up tests should be done, said Dr. Paul Nathan, a cancer specialist at the Hospital for Sick Children in Toronto. He led the study and gave results Monday at an American Society of Clinical Oncology meeting in Florida.

More than 11 million Americans are cancer survivors, including more than 325,000 who were diagnosed when they were 15 or younger.

Researchers used several government-sponsored studies to compare screening behaviors among 8,318 cancer survivors in the United States and Canada, more than 2,660 of their siblings, and 8,318 healthy people from the general population.

Of the cancer survivors who were at increased risk for a second cancer because of childhood radiation treatments, less than 12 percent were getting colonoscopies every five years, as recommended for survivors. Only 46 percent had had a mammogram within the previous two years, and only 27 percent had had an exam for skin cancer, the most common radiation-linked cancer in survivors.

Those rates were all better among siblings and the general public, although those groups don't need certain screenings as often as survivors do -- every 10 years for colonoscopies, for example.

Researchers are less confident about the skin cancer numbers, because doctors may have done this exam without explicitly telling patients what they were checking.

Still, there is concern that a psychological burden is keeping cancer survivors from getting screenings that can save their lives.

"That's true of people other than children, too," said Ellen Stovall, president of the National Coalition for Cancer Survivorship who has battled cancer three times herself.

"Many cancer survivors have had enough of doctors and hospitals and may purposely avoid certain types of screening that might give them bad news," said Dr. Philip Rosoff, who directs a follow-up clinic for cancer survivors at Duke University.

Others find the opposite problem -- doctors who are reluctant to order screening tests because they think survivors are overreacting.

Stephanie Leser said her doctors resisted her requests for a mammogram when she was 21, even though she had a cancer history and her mother had had breast cancer. Leser, of Wake Forest, N.C., had been treated for Hodgkin's lymphoma at age 10, and guidelines say she should start getting mammograms at age 18 to watch for breast cancer.

"It's been a huge fight" to get a mammogram, she said.

About the time she finally did, she was discovered to have thyroid cancer that likely was due to her childhood radiation treatments. Now, at age 30, she works as a pediatric cancer nurse at Duke and argues with any doctor who won't order a screening test.

"Another cancer could come and bite me in the butt. I just want to be as prepared as I possibly can," she said.

Sophia Smith, 50, of Chapel Hill, N.C., said she wasn't told to get follow-up tests after completing treatment for Hodgkin's lymphoma at age 16.

"They basically told me I was cured and to follow up with my primary care," she said.

Thirteen years ago, she found a breast lump.

"The physician wasn't concerned about it because I was in my 30s. I advocated for myself to get a mammogram. I had a feeling something was not right," and the test revealed a tumor, she said.

Now, she is vigilant about screening.

"I go to the doctor every year. I don't like to go, I don't like the tests. But I know it's the only way you can beat the disease," she said.

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