By Corinna Wu

Can Doctors Reduce the Risk of Radiation-Related Second Cancers?

By Corinna Wu

Early diagnosis and more effective treatments have increased survival for patients with many types of cancer. But those very life-saving treatments sometimes lead to another bout with the disease years later. Patients who receive radiation therapy, for example, face a slightly higher risk of developing a secondary cancer—a solid tumor or leukemia. The increased risk is minuscule, says Stephen H. Petersdorf of the University of Washington and the Seattle Cancer Care Alliance, “but it’s higher than if they never had these exposures.”

Now, researchers have developed a computer model to better predict these delayed effects. Currently, a computer designs the radiation therapy for each patient in order to maximize the dose to the tumor while minimizing early side effects, but not the late-effect of radiation-induced cancer. “So the idea is that if you have a model for how it’s produced, you can train the computer to think about this, too, when it’s designing the treatment,” says David J. Brenner, a radiation biologist at Columbia University Medical Center in New York City. He and his colleagues described their model in the Dec. 20, 2006, Journal of the National Cancer Institute.

The model takes into account the different ways in which secondary leukemias can start, including the fact that blood stem cells can circulate to other parts of the body, far from where the radiation was focused. The risks for secondary cancers calculated using the model match well with the numbers of those cancers observed among actual cancer patients who have undergone radiation therapy.

Now, the researchers hope their model will be incorporated into treatment-design software and tested to see if it helps reduce secondary cancers without harming radiation’s ability to kill an original tumor. If these tests prove successful, then manufacturers could build the new model into the software sold with radiation-therapy machines. “It’s not just leukemia risks we hope to reduce,” says Brenner. “It’s all radiation-induced cancers."