Cancer patients who underwent radiation therapy as children are at greater risk of developing diabetes later in life, a finding that should prompt changes in treatment guidelines, French and British researchers said.
By age 45, 6.6 percent of those who had received radiation were diagnosed with diabetes, in which the body lacks or becomes resistant to the hormone insulin, according to the survey of more than 2,500 patients. That compared with 2.3 percent of those who hadn’t had radiation. The higher the dose, the more likely the children were to develop diabetes, the researchers wrote in The Lancet medical journal today.
About four out of 10 people with cancer have radiation therapy, or high-energy X-rays intended to destroy tumors, according to the U.K.’s National Health Service. When exposed to radiation, cells in the tail of the pancreas responsible for insulin production may be damaged, which probably accounts for the higher incidence of diabetes, the researchers said.
“The pancreas needs to be regarded as a critical organ when planning radiation therapy, particularly in children,” said Florent de Vathaire from the Center for Epidemiology and Public Health at the Gustave Roussy Institute in France, an author of the research, in an e-mailed statement.
Lack of Insulin
Diabetes, caused by a lack of insulin needed to convert blood sugar into energy, rarely causes death, though it can lead to life-threatening complications such as kidney damage and cardiovascular disease. The condition can be managed through a combination of dietary control, drug therapy and insulin injections.
Any potential increase in cases raises important public health questions at a time when diabetes cases are rapidly rising around the world, the researchers said. About 366 million people had the illness last year, according to estimates by the International Diabetes Federation. That number will probably increase to 552 million by 2030, caused by an aging population and lifestyle changes in poorer countries, according to the group.
The British and French researchers surveyed childhood cancer patients at least 20 years after their treatment. The scientists then used mathematical models and information about radiation therapy at the time of treatment to reconstruct how patients were exposed to radiation. Childhood cancer survivors undergoing treatment before the age of 2 were most sensitive to radiotherapy, the study found.
Children with kidney cancer were most at risk of developing diabetes, with 14.7 percent of those treated with radiation diagnosed with the condition by age 45, the study found. That’s probably because the radiation treatment was focused on the abdominal area, which includes the pancreas, the researchers said.
Before the study, the effect of cancer treatment on the pancreas was largely unknown, said Kevin Oeffinger, director of the adult long-term follow-up program at Memorial Sloan-Kettering Cancer Center in New York, in a comment accompanying the article in The Lancet.
“The clinical implications of this study are important, since radiation remains an integral part of therapy for many children” with kidney cancer, Oeffinger wrote. “Further study is needed to clarify the mechanisms underlying diabetes after abdominal radiation.”
Although the precise causes of the association remain unknown, the findings suggest that radiation therapy targeting the pancreas should be at the lowest intensity possible, said de Vathaire.