Proton Radiation Is Not Associated with Increased Risk of Secondary Cancers When Compared with Photon Radiation
A retrospective cohort study of 558 patients treated with proton radiation from 1973 to 2001 at the Harvard Cyclotron Laboratory in Cambridge, Massachusetts, and data from 558 matched patients treated with photon therapy in the Surveillance, Epidemiology, and End Results (SEER) Program cancer registry, found that proton radiation therapy did not significantly increase the risk of secondary malignancies compared with proton therapy. The study was published in the International Journal of Radiation Oncology • Biology • Physics.
The patients were matched by age when radiation treatment started, sex, year of treatment, cancer histology, and cancer site. The primary outcome measure was the incidence of second malignancies after radiation.
The median duration of follow-up was 6.7 years and 6.0 years in the proton and photon patients, respectively, and the median age at treatment for both groups was 59. The researchers found that second malignancies occurred in 29 proton patients (5.2%) and 42 photon patients (7.5%). After adjusting for sex, age at treatment, primary site, and year of diagnosis, proton therapy was not associated with an increased risk of second malignancy (adjusted hazard ratio = 0.52 [95% confidence interval = 0.32–0.85]; P = .009).
Obstacles to Proton Therapy Use
The researchers undertook the study to assess the long-term sequelae of proton therapy because use of the technology is becoming more commonplace, although there are still obstacles to its full implementation in cancer treatment. According to an article on the National Comprehensive Cancer Network (NCCN) patient website, although there are advantages of proton therapy over conventional photon x-ray therapy, including its ability to deposit radiation doses directly to the tumor site and thus preserving healthy surrounding tissue, constructing centers to house the new technology and treat patients is still expensive. According to the NCCN article, only 10 medical facilities in the United States offer proton therapy as of March 2012.
Other drawbacks include:
- Not all insurance carriers cover proton treatment because it is still so new.
- Physicians, physicists, and therapists need to be trained in the use of proton therapy.
- Greater awareness of the benefits of proton therapy needs to be established among physicians and patients.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
