A Comparative Study of Sequential Boost Versus Simultaneous Integrated Boost Radiation Therapy in Postoperative Treatment of Extremity and Trunk Wall Soft Tissue Sarcoma.

PURPOSE: To compare toxicities and oncological outcomes of postoperative sequential boost (Seq) versus simultaneous integrated boost (SIB) radiation therapy in extremity and trunk wall soft tissue sarcoma.

METHODS AND MATERIALS: This retrospective study compared postoperative Seq and SIB radiation therapy in 152 patients with extremity/trunk wall soft tissue sarcoma, analyzing clinicopathologic characteristics, major wound complications, Radiation Therapy Oncology Group (RTOG) late toxicity, and oncological outcomes (overall survival [OS], disease-free survival [DFS], local recurrence [LR], and distant metastasis) from a prospectively maintained database.

RESULTS

Baseline characteristics (age, tumor location/site) were similar, but tumors were significantly larger in the SIB group (median 12.2 cm vs 7.4 cm; P = .007). Radiation therapy was delivered as Seq (66 Gy: 50 Gy/25 fractions + 16 Gy/8 fractions) or SIB (56/66 Gy in 33 fractions). Median follow-up was 5.3 years but was substantially longer for the Seq group (7.4 vs 3.4 years; P < .001). Major wound complications were comparable (Seq: 19.7% vs SIB: 17.9%; P = .91) with tumor size as the only significant factor (odds ratio, 1.08; P = .018). Late ≥G2 toxicities were similar: skin (23.2% vs 23.1%), subcutaneous fibrosis (37.2% vs 25.0%; P = .29), joint stiffness (7.0% vs 11.5%; P = .51), and edema (7.0% vs 13.5%; P = .50). One bone fracture occurred in the SIB cohort. Five-year LR was 3.1% (Seq) versus 2.4% (SIB). There were no significant differences in OS, DFS, LR, or distant metastasis. Multivariable analysis significantly linked age, tumor size, and grade 3 to OS, and tumor size and grade 3 to DFS.

CONCLUSIONS

Postoperative radiation therapy in soft tissue sarcoma using Seq or SIB appears to have similar toxicity and oncological outcomes, despite larger tumors in the SIB group. As SIB requires intensity modulated radiation therapy-which prior studies show reduces long-term adverse effects-it may be preferred, particularly in patients with larger treatment volumes undergoing postoperative radiation therapy.