March 27, 2001 (New Orleans) -- As treatments for childhood cancers improve and cancer survivors live longer, there is mounting evidence that people who survived a childhood cancer may be at increased risk of developing another cancer later on. These second incidences of cancer do not seem to be directly related to the first cancer but rather are linked to the treatment initially received, according to a large North American study.
"The leading disease cause of death [in children in the U.S.] far and away is cancer," said expert Barton A. Kamen, MD, PhD, during a press conference Tuesday at the annual meeting of the American Association for Cancer Research held here.
Kamen, an American Cancer Society clinical research professor at the Robert Wood Johnson Medical School Cancer Institute of New Jersey, was not involved in the study but commented on its findings. "Fortunately, [cancer is still] a relatively rare disease. ... There are about 8,000 to 10,000 new diagnoses of cancer in kids in the U.S. every year. ... Kids get leukemia [most often,] and the remarkable cure rate in leukemia is such that in our last 15 years, 90% of the children I've personally taken care of -- which is almost 400 -- are still alive, and 80% of them are free of disease."
That's the good news.
The bad news is that as more and more children survive cancer and live into adulthood, long-term consequences of the cancer therapy they received are sometimes rearing their ugly heads.
Researcher Joseph P. Neglia, MD, PhD, said at the press conference that "as of this year, we're projecting that approximately 70% of all children diagnosed with cancer in the U.S. will be cured of their disease. ... Because of this, it's the responsibility of clinicians and investigators to understand the long-term consequences of this curative therapy in children."
He added that approximately one in 1,000 people in the U.S. between the ages of 20 and 30 is a survivor of childhood cancer. Neglia is an associate professor of pediatrics at the University of Minnesota Medical School in Minneapolis.
For almost 10 years, Neglia and his colleagues have been studying the health and well-being of nearly 14,000 people from the U.S. and Canada who have survived childhood cancer for at least five years. The average length of survival since cancer therapy among these study participants is 15 years.
So far, 298 of these individuals who survived a childhood cancer have gone on to develop different cancers later in life. The most common of these are breast, thyroid, and brain cancer. Both Kaman and Neglia emphasized the importance of keeping these findings in perspective. That is, the risk of developing a cancer later in life after being treated for cancer in childhood is still small and is far outweighed by the great benefits of that initial treatment.
But overall, these individuals appear to have a six times greater risk of developing another cancer compared to a similar people who did not have childhood cancer. Those at highest risk for developing another cancer later in life are those who had Hodgkin's disease or who received radiation therapy in childhood. Those treated for leukemia in childhood are at greatest risk for developing a brain tumor later on.
"We did not find any association at all between age at therapy and the risk of breast cancer," said Neglia. "Previous studies have suggested that young girls treated for Hodgkin's disease with radiation therapy to the chest during times of breast development may be most susceptible [to developing breast cancer later on]. That actually has led to gender and age-specific recommendations for therapy. Our results contradict this finding and really stress the importance of close follow-up for any girl who received radiation to the chest at any point in childhood."
"Patients [who had cancer in childhood] need to know what the treatment was [that] they received, and they need to speak to a ... physician who is actually versed in these long-term consequences of therapy, to discuss what, if any, recommendations for follow-up are important," said Neglia. "An example of this is that any woman who received radiation to the chest during childhood [should] receive a mammogram, probably, at age 25."