Sandwiched between multiple reports and alarms about opioids being overprescribed and abused comes this: People who have survived cancer may get even more pain pills than the rest of the population. In this case, however, there may be good reasons.

Although most people are well-aware that cancer can return years after it has been treated, oncologists say that there is an oversimplified belief that the disease, once banished from the body, has few lingering effects.

"Not everybody gets to wear pink ribbons and be happy and go on the [breast-cancer fund-raising] walk," said Curtis Miyamoto, radiation oncology chair at Temple University's Lewis Katz School of Medicine.

Some patients have continuing chronic pain from the treatment. For early-stage lung cancer patients, for example, survival may depend on significant surgery. Some chemotherapies, which kill both cancerous and healthy cells, may cause long-term pain in some patients. Cancer survivors who later experience unrelated pain may be reminded of their diagnosis and seek pain medication earlier than other people would, he said.

The new study, by Toronto researchers using records from Ontario's universal health plan, did not attempt to determine why people were given pain pills. It simply compared records of opioid prescriptions for 8,601 low-income cancer survivors with no recurrence of the disease against an identical number of people who had never had cancer, matched by age, sex, and income. The cancer survivors were receiving 20 percent more opioid prescriptions five years after their diagnosis.

The rate was the same 10 years out.

"We were very surprised," said lead author Rinku Sutradhar, who studies cancer statistics and guidelines at the Institute for Clinical Evaluation Sciences, an independent research organization.

The team had hypothesized that there would be no difference between the two groups, Sutradhar said, because Canadian guidelines recommend that cancer patients with no recurrence after five years be referred to primary-care doctors by oncologists, and treated the same as any other patient.

Guidelines in the United States are more variable, physicians here said, and some patients may continue seeing a cancer specialist for the rest of their lives.

The study, being published Monday in the journal Cancer, found that the highest prescription rates were largely in people with lung, gynecological, and gastrointestinal cancers, all of them known to be painful. There was no increase in prescribing for brain, breast, colorectal, and prostate cancers, among others.

Marilyn J. Heine, a physician at Regional Hematology Oncology Associates in Bucks County, said the findings made sense.

"Cancer survivors may have long-term pain that results from chemotherapy, radiation therapy, and/or surgery. In the study, the cancer groups with the greatest difference are apt to have received a combination of these treatments," Heine said.

Guidelines for prescribing opioids, which are increasingly seen as a way to prevent excess prescribing by physicians and raise awareness among the general public, typically cover the treatment of  "chronic noncancer pain." Historically, cancer was  excluded from general guidelines for several reasons, said Roger Chou, a professor at Oregon Health and Science University's School of Medicine, and a coauthor of federal guidelines released last year by the Centers for Disease Control and Prevention.

Some cancer patients were dying from the disease, so there was less concern about addiction and abuse, he said. In addition, cancer patients "are more likely to have a 'true' lesion that is causing the pain" and "getting bigger," he said. By contrast, with "a lot of low-back pain we can't see what is causing it."

Still, as cancer treatments have improved, for many patients pain should, as well.

Yet for some doctors, knowing that their patient survived cancer might have "some subconscious effect" that makes them more willing to prescribe opioids, said Chou, an internal medicine physician.

And while some cancer survivors do need powerful drugs to manage their pain, the new study's finding of higher prescription rates "raises the question,  'Is having a history of cancer kind of a ticket for more liberal prescribing?'  I'm not sure about that," Chou said.