Nov. 27, 2012 -- When 7-year-old Mykayla Comstock was diagnosed with leukemia in July, it was less than three days before her mother filed Oregon medical marijuana paperwork so the child could take lime-flavored capsules filled with cannabis oil.
The decision to give Mykayla the capsules came naturally to Erin Purchase, MyKayla's mother, who believes marijuana has healing power, but doctors aren't so sure it's a good idea.
"The first doctor was not for it at all," Purchase told ABCNews.com. "She was rude and she told us it was inappropriate. "Basically she blew up at us and told us to transfer to another facility."
They found a new doctor, who knows that Mykayla takes about a gram of cannabis oil a day -- half in the morning and half at night -- but he doesn't talk about it with them.
"This is our daughter," Purchase, 25, said. "If they don't agree with our personal choices, we'd rather they not say anything at all."
It's legal for a minor to enroll in the Oregon medical marijuana program as long as the child's parent or legal guardian consents and takes responsibility as a caregiver.
And Mykayla is not alone.
There are currently four other patients enrolled in the Oregon medical marijuana program between the ages of 4 and 9, six between the ages of 10 and 14, and 41 between the ages of 15 and 17, according to the Oregon Public Health Division. Severe pain, nausea, muscle spasms and seizures are among the top conditions cited for medical marijuana use.
Mykayla first started to feel sick in May, when she developed a rash, cough and night sweats. By mid-July, doctors found a mass in her chest and diagnosed her with T-cell acute lymphoblastic leukemia a few days later. The family relocated from Pendleton, Ore. to Portland to be near Randall Children's Hospital for treatment, which included chemotherapy.
At first, Mykayla wasn't responding well to her treatment, and doctors said she might need a bone marrow transplant. Then she started taking the cannabis oil pills. her mother said. By early August, Mykayla was in remission and the transplant was no longer necessary.
"I don't think it's just a coincidence," Purchase said. "I credit it with helping -- at least helping -- her ridding the cancer from her body."
Before Mykayla was diagnosed, Purchase had read about another young boy with cancer who received cannabis oil for nearly two years because his parents believed it kept him alive so much that they defied doctors' orders and broke Montana law to give it to him. She said she knew it was what she would do for her children if they ever got sick.
Cash "Cashy" Hyde died Nov. 14 at four years old, but his parents say he was never in any pain because of the oil.
Purchase said she, too, uses medical marijuana. She said it has helped with her kidney and liver disease since 2010, adding, "I feel that it saved my life"
However, Dr. Donna Seger, the executive director of the Tennessee Poison Center and a professor at Vanderbilt University, said cannabis has no effect on liver or kidney function, and it does not cure cancer.
"If it does anything, it decreases immunity," she said. "It doesn't fight cancer."
Dr. Igor Grant, who directs the University of California Center for Medical Cannabis Research in San Diego, said he's never studied marijuana's effects on children and it's not clear how the pills will affect Mykayla's development if she takes the drugs daily for a period of months or years.
"It's always a tricky issue prescribing really a medication of any kind to developing organisms because they may be more sensitive to the effects, specifically if the prescription drug has an effect on the brain," Grant said.
He said there have been basic laboratory studies that suggest pot slows cancer cells' ability to change, but those studies are only theoretical. They include no clinical data and or animal data.
The American Academy of Pediatrics opposes treating children with medical marijuana.
"The issue is that marijuana isn't a medicine," Dr. Sharon Levy, of the AAP, told the Oregonian.
Seger said she has several concerns about a 7-year-old taking pills filled with cannabis oil because there is little research on its long-term effects on children. Cannabis could have potentially negative effects on cognitive development in children since it affects cognitive ability in adults.
But Purchase said she wasn't afraid to give her daughter the pills last summer. She was a little nervous about determining the right dose. She and her fiancé, Brandon Krenzler, who helped raise Mykayla since she was 3 years old, started MyKayla with .07-gram doses.
"It took a while to get her adjusted to it," Purchase said. "She acted more funny when she first started taking it and after a while gained tolerance. Now, when she takes it, you can't even tell. She's very normal."
Purchase said she knew she'd done the right thing the day Mykayla missed a dose of her cannabis oil pills and her 17-month old sister walked into a room holding string cheese. The smell made Mykayla so sick that she threw up on the spot.
"She actually asked for her dose," Purchase said, adding that she's less perky without it. "She doesn't use pain pills or nausea pills. She has not even lost a single pound since her diagnosis."
Dr. Michel Dubois, who works in NYU Langone's Pain Management Center, said using cannabis is still controversial because of its side effects and addictive qualities.
"This is a new ethical problem because you've got a medication, which is known to have psychoactive affects, approved by the parents and given to a child," he said, adding that the child doesn't have much choice in the matter. (Psychoactive drugs disrupt communication in the brain and alter normal awareness, behavior and mood, according to the National Institute on Drug Abuse.)
Dubois said it would be better to give a child other drugs for nausea because the cannabis oil likely contains at least 50 or 60 different chemicals with unknown long-term health effects. If Mykayla's life expectancy is limited, her risk of toxicity will also be limited. However, if she is expected to make a full recovery, Dubois said there is a worry that the cannabis will add health problems later on.
He said the cannabis shouldn't be used for more than a month or two.
Although Mykayla's doctors told Purchase she was in remission on Aug. 6 when her blood cell counts returned to normal, Mykayla will undergo two and a half or three more years of chemotherapy so that she can one day be officially cured, Purchase said. That could mean years of more medical marijuana.