It's a situation too agonizing to contemplate - a child dying and in pain. Now a small but provocative study suggests that doctors may be giving fatal morphine doses to a few children dying of cancer, to end their suffering at their parents' request.

A handful of parents told researchers that they had asked doctors to hasten their children's deaths - and that doctors complied, using high doses of the powerful painkiller.

The lead author of the study and several other physicians said they doubt doctors are engaged in active mercy killing. Instead, they speculate the parents interviewed for the study mistakenly believed that doctors had followed their wishes.

A more likely scenario is that doctors increased morphine doses to ease pain, and that the children's subsequent deaths were only coincidental, said lead author Dr. Joanne Wolfe, a palliative pain specialist at Dana-Farber Cancer Institute and Children's Hospital in Boston.

The American Medical Association, American Academy of Pediatrics and most other mainstream doctor groups oppose mercy-killing but say withholding life-prolonging treatment for dying patients can be ethical.

Dr. Douglas Diekema, a medical ethicist at Seattle Children's Hospital, said the study results are not surprising.

"I have no doubt that in a small number of cases, some physicians might cooperate with a parent's desire to see a child's suffering ended. This might include giving a drug for sedation or pain control that also suppresses the drive to breathe.

"Most physicians don't intentionally push that drug to the point of stopping a child's breathing, but some may be comfortable not intervening if a child stops breathing in the course of treating him or her for discomfort," Diekema said.

The study was published Monday in the March edition of Archives of Pediatrics & Adolescent Medicine. It was based on interviews with parents of 141 children who had died of cancer and were treated at three hospitals, in Boston and Minnesota.

Among parents studied, one in eight, or 13 percent, said they had considered asking about ending their child's life, and 9 percent said they had that discussion with caregivers. Parents of five children said they had explicitly requested euthanasia for their dying children, and parents of three said it had been carried out, with morphine.

"If there was absolutely no other option, and the patient is suffering, then why wouldn't you" hasten death? said David Reilly, a Boston-area man whose 5-year-old son died of cancer 11 years ago.

Reilly was not part of the study, but Wolfe, the study author, treated his son. The boy had soft-tissue tumors that threatened to spread to his throat and choke him.

"I remember thinking what a horrible, horrible way to go," Reilly said. He recalls asking Wolfe if his son began to suffer, '"Can we just get it over with quickly?'" Wolfe told him no.

Wolfe said in an interview that euthanasia "is going beyond a moral stance that I hold for myself in terms of controlling when a person dies."

She said she could not comment when asked if she knew of any cases occurring at her hospitals, which both were involved in the study.

The third hospital was Children's Hospitals and Clinics of St. Paul, Minn. Dr. Susan Sencer, a cancer specialist there who did not take part in the study, said in a text message that doctors will often tell parents this when dying children are suffering: "'To alleviate pain and suffering we may need to increase the narcotics; increasing the narcotics may result in respiratory depression, which may hasten death,' so that they are aware of the trade-off."

Wolfe said the study highlights the challenges of treating dying children: Parents cannot tolerate seeing their children suffer and do not know about all the legal options for pain relief, which can include sedating children into unconsciousness. Also, many doctors are uncomfortable discussing such issues.

Dr. Melanie Brown, a palliative care specialist at the University of Chicago's Comer Children's Hospital, said she's never had parents ask her to end their child's life, but the general topic has come up.

She said when parents mention the idea, "What they're talking about is ending the pain."

Learning ahead of time about options other than euthanasia can help make these deaths more comfortable for children and their parents, she said.

Dr. Walter Robinson, an ethicist and associate pediatrics professor at Vanderbilt University, said many doctors lack expertise in treating dying children's pain, and many also worry about using opiates including morphine to treat children's pain because there's an unreasonable fear of addiction.

"The lesson we should learn from the paper is the need for expert pain control. That ought to be available in every children's hospital and to every child with a life-limiting illness," Robinson said.