Histologic Appearance After Preoperative Radiation Therapy for Soft Tissue Sarcoma: Assessment of the European Organization for Research and Treatment of Cancer-Soft Tissue and Bone Sarcoma Group Response Score

Int J Radiat Oncol Biol Phys. 2017 Jun 1;98(2):375-383. doi: 10.1016/j.ijrobp.2017.02.087. Epub 2017 Feb 24.


Purpose: To critically assess the prognostic value of the European Organization for Research and Treatment of Cancer-Soft Tissue and Bone Sarcoma Group (EORTC-STBSG) response score and define histologic appearance after preoperative radiation therapy (RT) for soft tissue sarcoma (STS).

Methods and materials: For a cohort of 100 patients with STS of the extremity/trunk treated at our institution with preoperative RT followed by resection, 2 expert sarcoma pathologists evaluated the resected specimens for percent residual viable cells, necrosis, hyalinization/fibrosis, and infarction. The EORTC response score and other predictors of recurrence-free survival (RFS) and overall survival (OS) were assessed by Kaplan-Meier and proportional hazard models.

Results: Median tumor size was 7.5 cm; 92% were intermediate or high grade. Most common histologies were unclassified sarcoma (34%) and myxofibrosarcoma (25%). Median follow-up was 60 months. The 5-year local recurrence rate was 5%, 5-year RFS was 68%, and 5-year OS was 75%. Distribution of cases according to EORTC response score tiers was as follows: no residual viable tumor for 9 cases (9% pathologic complete response); <1% viable tumor for 0, ≥1% to <10% for 9, ≥10% to <50% for 44, and ≥50% for 38. There was no association between EORTC-STBSG response score and RFS or OS. Conversely, hyalinization/fibrosis was a significant independent favorable predictor for RFS (hazard ratio 0.49, P=.007) and OS (hazard ratio 0.36, P=.02).

Conclusion: Histologic evaluation after preoperative RT for STS showed a 9% pathologic complete response rate. The EORTC-STBSG response score and percent viable cells were not prognostic. Hyalinization/fibrosis was associated with favorable outcome, and if validated, may become a valid endpoint for neoadjuvant trials.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Cell Survival
  • Disease-Free Survival
  • Female
  • Fibrosarcoma / mortality
  • Fibrosarcoma / pathology
  • Fibrosarcoma / radiotherapy
  • Fibrosarcoma / surgery
  • Fibrosis / pathology
  • Follow-Up Studies
  • Humans
  • Infarction / pathology
  • Kaplan-Meier Estimate
  • Leiomyosarcoma / mortality
  • Leiomyosarcoma / pathology
  • Leiomyosarcoma / radiotherapy
  • Leiomyosarcoma / surgery
  • Liposarcoma / mortality
  • Liposarcoma / pathology
  • Liposarcoma / radiotherapy
  • Liposarcoma / surgery
  • Male
  • Middle Aged
  • Necrosis / pathology
  • Neoplasm, Residual
  • Proportional Hazards Models
  • Sarcoma / mortality
  • Sarcoma / pathology*
  • Sarcoma / radiotherapy*
  • Sarcoma / surgery
  • Time Factors
  • Treatment Outcome
  • Tumor Burden