document: Benefits of Radiation Therapy Outweigh Risks of a Second Cancer : Study Likelihood that radiotherapy will cause another tumor is low , researchers say TUESDAY , March 29 -LRB- HealthDay News -RRB- - The odds a second cancer will develop after radiation treatment for a first cancer are relatively low , U.S. National Cancer Institute researchers report . In a long-term study of more than 600,000 cancer survivors , an estimated 8 percent of second cancers were attributable to radiation treatment for the original cancer , according to the study . The results suggest that other factors , such as lifestyle risks and genetics , cause the majority of second cancers , the researchers say . '' `` The findings can be used by physicians to really put the risks into perspective when they are talking treatment options with their patients , '' '' said lead researcher Amy Berrington de Gonzalez , an investigator in the NCI 's radiation epidemiology branch . Patients should feel reassured , she added . '' `` In general , the risks -LSB- of radiation therapy -RSB- are smaller than the benefits , '' '' she said . The study , published online March 30 in The Lancet Oncology , is the first to quantify the cancer risks posed by radiation treatment for different malignancies . Berrington de Gonzalez and colleagues collected data on 647,672 adult cancer survivors included in the U.S. Surveillance , Epidemiology and End Results cancer registries . All had survived five years or longer after cancer treatment , and follow-up ran from 1978 to 2007 . The researchers looked at outcomes for 15 different types of cancer for which radiation treatment is routine , including cancers of the rectum , larynx , lung , breast , cervix , testicles , prostate , eye and orbit , brain and thyroid . Over the 30 years of follow-up , 9 percent of these participants developed a second cancer . Of these , about 3,300 -LRB- 8 percent -RRB- might have been the result of radiation treatment , the study authors said . Second cancers related to earlier radiation therapy varied by type , the researchers noted . More than half of the second cancers developed in breast and prostate cancer survivors . Four percent of second cancers were in the eye , and 24 percent were cancer of the testicles , the researchers found . Patients who had their initial cancer when young were at the greatest risk of developing a second cancer . Also at high risk were those whose organs received high doses of radiation . The likelihood of developing a secondary cancer increased over time . When these data are put in perspective , the absolute risk for a second cancer is 3 in 1,000 over 10 years after radiation therapy and 5 in 1,000 over 15 years , Berrington de Gonzalez said . '' `` We know that radiation therapy can increase the risk of getting another cancer , but at the same time the benefits outweigh the risks , '' '' said Elizabeth Ward , national vice president for intramural research at the American Cancer Society . Radiation therapy is an important and relatively safe treatment for cancer , she added . Thanks to treatment advances , Ward said , radiologists today are better able to pinpoint treatment and limit exposure to healthy tissue than they were in the past . Now , studies are needed to determine the cancer risks from newer radiation treatments , the authors noted . Dr. Anthony D'Amico , chief of radiation oncology at Brigham and Women 's Hospital in Boston , agreed that the NCI findings are encouraging . '' `` Despite people 's concerns , radiation is relatively safe with regard to the issue of second cancers , because the number of cancers that result from it are very small , '' '' D'Amico said . More information
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