Intensity-Modulated Radiation Therapy Improves Survival in Patients With Head and Neck Cancer
Patients with cancers of the head and neck who received intensity-modulated radiation therapy experienced improved outcomes, as well as reduced toxicities, compared to patients receiving conventional radiation therapy, according to findings published online in Cancer by Beadle et al. The study is the first to document this finding in a large population-based group, as well as the first to suggest intensity-modulated radiation therapy could improve outcomes in head and neck cancer patients.
“Previous studies indicated that patients treated with intensity-modulated radiation therapy did better when it came to treatment-related side effects, however these studies were not designed to examine survival,” said Beth Beadle, MD, PhD, Assistant Professor in the Department of Radiation Oncology at The University of Texas MD Anderson Cancer Center. “The survival data were not well-known because intensity-modulated radiation therapy is intended to spare normal tissues but still deliver radiation to the tumor, so previous models assumed it was equivalent survival at best.”
Intensity-modulated radiation therapy employs multiple beams of radiation, allowing oncologists to provide a dosage that conforms to the tumor, often at varying intensities, while limiting exposure to surrounding tissue. Since being approved in 1999 for the treatment of head and neck cancer, use of the therapy has substantially increased due to its advantages in being able to target complicated tumors while minimizing patient side effects such as xerostomia, dental complications, fibrosis, and range of motion impairments.
Study Details
Researchers on the population-based retrospective study used the Surveillance, Epidemiology, and End Results (SEER)-Medicare database, compiled by the National Cancer Institute, to identify 3,172 patients treated for head and neck cancer between 1999 and 2007 who received either conventional radiation therapy or intensity-modulated radiation therapy.
In total, 1,056 patients were treated with intensity-modulated radiation therapy and 2,116 were treated with conventional therapy. All head and neck cancer subtypes were included, with the most common, squamous cell carcinoma, accounting for 91.2%. The primary outcome was cause-specific survival.
To account for differences in the patient population with those being treated with intensity-modulated radiation therapy possibly representing a different cohort due to the evolution of treatments, researchers used propensity scoring to create a matched comparison. This scoring model takes into account age at diagnosis, gender, race/ethnicity, income and education, among other factors.
Results Show Outcomes Improved
With a median follow-up of 40 months, the investigators found that patients treated with intensity-modulated radiation therapy had a statistically significant improvement in cause-specific survival compared to those treated with conventional therapy, 38.9% vs 18.9%, respectively.
Although propensity scoring matched patients for known variables, the researchers noted there was still a possibility for bias in the two treatment groups as a result of unmeasured variables. To account for this, an instrumental variable model was used that also demonstrated intensity-modulated radiation therapy increased survival.
“From a scientific perspective, the findings support the use of [intensity-modulated radiation therapy] and suggests we can provide excellent care while optimizing cancer outcomes and reducing toxicities,” Dr. Beadle said. “At a more global level, with concerns about health-care financing and resource allocation, [intensity-modulated radiation therapy] is more expensive than conventional radiation therapy, but the data suggest it’s worth it.”
Cost-Effectiveness
The authors noted a separate, recent study by Yong et al that examined the cost-effectiveness of intensity-modulated radiation therapy in the treatment of oropharyngeal cancer found reason to support its use. Despite increased upfront costs, the study found intensity-modulated radiation therapy could avoid a case of xerostomia with an incremental cost of $4,532.
Dr. Beadle said additional work is required to more closely examine the cost-effectiveness of intensity-modulated radiation therapy. However, she noted that if the therapy can reduce or eliminate subsequent disease recurrences, or treatment-related side effects, the cost impact could be favorable.
With observational studies, the authors said limitations do exist including the uncertainty of Medicare claims data and the absence of data for younger patients. Additionally, the authors note there was an absence of human papillomavirus status, which may affect tumor control.
Dr. Beadle is the corresponding author of the Cancer article.
The study authors reported no potential conflicts of interest.
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®.
