By one estimate, 75 percent to 80 percent of patients can now expect to live five or more years, up from only 20 percent to 25 percent 30 years ago.
That statistic is one of the first major findings to be released from an unprecedented study into the long-term health of childhood cancer survivors. It was made public yesterday at the American Society of Clinical Oncology meeting in Orlando, Fla.
This encouraging news means aggressive treatments pioneered in the 1970s are working, and working well. However, it also means that, while doctors know the short-term effects of the drugs used to treat young cancer patients, they have little idea what the long-term health prospects are because past survival rates were so low.
"It's become so important to find out what is happening long-term with these kids so we can adjust treatment for kids still coming along," says Dr. Stuart Toledano, a professor of pediatrics and the head of pediatric oncology at the University of Miami. "If we can't prevent the disease, at least we want to give treatment that's not only effective but also the least toxic."
In addition, some treatments may have unforeseen effects as a person ages, Toledano says.
For the Childhood Cancer Survivor Study, researchers at 25 sites nationwide gathered information from 14,000 young people who had had cancer between 1970 and 1986, before they turned 21. The study, which began nine years ago, is funded primarily by the National Cancer Institute.
The study found the majority of survivors over the age of 18 considered themselves to be in good general health, with a quality of life comparable to anyone else.
However, the news isn't all good on all fronts.
Female cancer survivors were found to have more problems with mental health, anxiety and physical activities. Also, survivors of brain tumors, Hodgkin's disease, bone tumors and soft tissue sarcomas seemed to be at the highest risk for health problems.
There was a significantly higher occurrence of pulmonary complications, including lung fibrosis, emphysema and pneumonia, in cancer survivors. Radiation and some forms of chemotherapy are known to have short-term adverse effects on the lungs.
The study confirms that damaging effects can also emerge months and years after therapy, says lead investigator Leslie L. Robison, a professor of pediatrics at the University of Minnesota Medical School.
Survivors of acute lymphoblastic leukemia were much more likely to be obese or overweight than their siblings, especially if they had received cranial radiation. Cranial radiation has been a mainstay of leukemia therapy because it prevents leukemia cells from entering the central nervous system, Robison says.
The long-term health implications of obesity are, of course, considerable.
"If you add that on to a patient or survivor who may have received chemotherapy, which could damage the heart, we may be setting up a population of survivors who are at an extremely high risk for cardiovascular events," Robison says. "If that's the case, that group needs to be followed exceedingly closely."
Bone tumor survivors, on the other hand, reported few difficulties, regardless of whether they had had a limb amputated.
"At this stage, analyses are suggesting that [bone tumor] survivors don't show any difference in terms of physical function, as well as quality-of-life perception," Robison says. This information could help families and physicians when they're faced with the decision of having to amputate or undergo a different procedure that involves its own risk.
The just-released results are the tip of the iceberg. The study will continue indefinitely, while investigators research a whole spectrum of potential health drawbacks from cancer treatments, including the possibility of premature menopause and reduced fertility. Robison expects an average of 10 to 12 new scientific studies to be published every year.
The findings could be critical to the well being of children who are only now being diagnosed with cancer.
Toledano tells the story of a teen-aged boy he successfully treated for Hodgkin's disease more than 10 years ago. Toledano kept in touch infrequently with the boy's mother, learning when his former patient went to college, got married and settled down with a good job.
A year and a half ago, Toledano was shocked to learn the young man had died of a massive heart attack at the age of 30. The autopsy results showed he had extraordinarily severe thickening of the arteries.
In retrospect, Toledano says some of the chemotherapy the boy received, as well as radiation, could have affected his heart. Now, Toledano screens all his young adult patients for lipids, or fats, and other indicators of heart disease.
"You don't wait because the aging process might occur much earlier," he says. "Those things you only gain from long-term follow-up."
What To Do: More complete information on the study, also known as the Long-Term Follow-Up Study, can be found at the University of Minnesota Cancer Center. The American Cancer Society, the National Cancer Institute or the Foundation for Children's Oncology Group all have information on pediatric cancer.