A new report from the National Council on Radiation Protection and Measurements (NCRP) presents several conclusions and recommendations regarding the risks of radiotherapy in cancer treatment.
Second malignant neoplasms (SMNs) and cardiovascular disease (CVD) are among the most serious and life-threatening late adverse effects experienced by the growing number of cancer survivors worldwide and are due in part to radiotherapy, explained the report authors in a detailed summary published in Journal of the National Cancer Institute (2012;104:357-370). The goal of the NCRP is to develop solid long-term risk estimates and prediction models, establish research priorities, and identify concrete ways to prevent serious additional health problems in cancer survivors.
Some key findings of the NCRP are as follows:
- Although newer radiotherapy methods result in a different distribution of the radiation to organs and tissue than do older regimens, current models used to assess risk of SMNs and CVD are often based on the older treatments. Newer risk-prediction models should be based on the dose absorbed by the organ and the type of radiation prescribed.
- Modern radiation techniques and lower doses result in a much smaller risk of heart problems for patients, but an important noncancer cause of death for some survivors is radiation-related CVD, including pericardial disease, coronary artery disease, valvular dysfunction, conduction abnormalities, and stroke.
- Few studies have described survival after the diagnosis of an SMN.
- More studies are needed to analyze all aspects of the relationship between radiation dose and risks of SMNs and CVD.
- Follow-up studies of cancer survivors should evaluate populations treated with such modern radiotherapy methods as tomotherapy and cyber knife, and at reduced field sizes and lower dosages.
- Interactions between radiotherapy and other potential confounding factors, such as age, sex, race, tobacco and alcohol use, dietary intake, energy balance, and genetic susceptibility should be investigated.
The NCRP also calls for the construction of comprehensive risk-prediction models for SMNs and CVD so that follow-up guidelines and prevention and intervention strategies can be developed.