Reduced Local Recurrence With Intensity-Modulated vs External-Beam Radiation Therapy in Primary Soft-Tissue Sarcomas of the Extremity
There are no large-scale direct comparisons of outcomes with intensity-modulated radiation therapy vs conventional external-beam radiation therapy in patients with soft-tissue sarcoma of the extremity. In a single-institution experience reported in the Journal of Clinical Oncology, Folkert et al at Memorial Sloan Kettering Cancer Center found that use of intensity-modulated radiation therapy was associated with significantly reduced risk of local recurrence in patients with nonmetastatic extremity soft-tissue sarcoma.
Study Details
The study included 319 consecutive adult patients with primary nonmetastatic soft-tissue sarcoma of the extremity treated with limb-sparing surgery and adjuvant radiation therapy between January 1996 and December 2010. External-beam radiation therapy was used in 154 patients, and intensity-modulated radiation therapy in 165 patients with similar dosing schedules.
The intensity-modulated radiation therapy and external-beam radiation therapy groups were similar in terms of tumor location, histology, tumor size, tumor depth, and use of chemotherapy. Patients receiving intensity-modulated radiation therapy were older (67% vs 58% > 50 years, P = .08) and more likely to have high-grade lesions (87% vs 78%, P = .05), close (< 1 mm) or positive margins (52% vs 40%, P = .04), and preoperative radiation (21% vs 3%, P < .001).
Local Recurrence Risk
Median follow-up was 90 months for patients receiving external-beam radiation therapy and 42 months for those receiving intensity-modulated radiation therapy. Median time to local recurrence was 18 months (range = 2–69 months) with conventional external-beam radiation therapy vs 18 months (range = 9–33 months) for intensity-modulated radiation therapy. Five-year local recurrence rates were 7.6% with intensity-modulated radiation therapy vs 15.1% for conventional external-beam radiation therapy (hazard ratio [HR] = 0.50, P = .04).On multivariable analysis adjusting for age and tumor size, intensity-modulated radiation therapy retained significance as an independent predictor of local recurrence (HR = 0.46, P = .02).
The investigators concluded: “Despite a preponderance of higher-risk features (especially close/positive margin) in the [intensity-modulated radiation therapy] group, [intensity-modulated radiation therapy was associated with significantly reduced local recurrence compared with conventional external-beam radiation therapy] for primary [soft-tissue sarcoma] of the extremity.”
Kaled M. Alektiar, MD, of Memorial Sloan Kettering Cancer Center, is the corresponding author for the Journal of Clinical Oncology article.
The study was supported by the National Cancer Institute. Murray F. Brennan, MD, FACS, reported an employment/leadership position and stock ownership with ZIOPHARM Oncology.
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®.
