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Targeted preoperative radiation reduces late toxicities in extremity sarcoma
The use of preoperative image-guided radiation therapy was associated with a reduction in late toxicities among patients with extremity soft tissue sarcoma, according to study results.
“This study proves that we are able to use this modern technology — image-guided radiotherapy — to irradiate smaller target volumes … and reduce long-term side effects in extremity sarcoma compared with conventional radiotherapy,” Dian Wang, MD, professor of radiation oncology at Rush University Medical Center, said in a press release. “This is one of few successful multi-institutional studies on localized sarcoma in almost a decade.”
Wang and colleagues evaluated data from 79 patients with extremity sarcoma who underwent image-guided radiation therapy — which helps spare the surrounding normal tissues from radiation — followed by limb-sparing resection. The median age of the population was 61 years, and the median tumor size was 10.5 cm.
Median follow-up was 3.6 years (range, 0.1-5). Five patients were unable to undergo disease resection due to metastatic tumor progression.
Data on late toxicities were available from 57 patients. At 2 years, six (10.5%) of these patients experienced a toxicity of grade 2 or worse, the most common of which included subcutaneous tissue fibrosis, joint stiffness and edema.
Researchers then compared these data with results from the National Cancer Institute of Canada SR2 (CAN-NCIC-SR2) phase 3 randomized study evaluating preoperative and postoperative conventional radiation therapy in extremity soft tissue sarcoma. The rate for grade 2 or worse toxicity at 2 years was significantly greater in the preoperative arm of the CAN-NCIC-SR2 trial compared with results from the current analysis (37% vs. 10.5%; P ˂ .001). The current analysis reported lower rates for grade 2 or worse fibrosis (5.3% vs. 31.5%), joint stiffness (3.5% vs. 17.8%) and edema (5.3% vs. 15.1%).
Twenty-five of the 79 patients in the analysis died during follow-up, 22 of whom died due to disease progression. Local treatment failure occurred in five patients.
Using CAN-NCIC-SR2 criteria, estimated 2-year local RFS was 94% (95% CI, 88.2-99.7), regional and/or distant RFS was 65.3% (95% CI, 54.2-76.3) and PFS was 61.5% (95% CI, 50.3-72.7). Estimated 2-year OS was 80.6% (95% CI, 71.8-89.4).
“[This study] should provide oncologists with validation and evidence of this new radiotherapy approach that takes full advantage of rapidly developing technologies,” Wang said. “The absence of marginal-field recurrence and favorable toxicity profiles suggest that parameters used in this study are appropriate for preoperative image-guided radiotherapy of extremity sarcoma.” – by Alexandra Todak
Disclosure: The researchers report stock ownership in; honoraria and research funding from; and employment, speakers bureau or consultant/advisory roles with 21st Century Oncology, Bayer/Algeta, Blue Earth, Dendreon, GlaxoSmithKline, Lumicell, Medivation/Astellas and Wolters Kluwer Health.