Correlation of Radiologic and Pathologic Response in Patients Receiving Neoadjuvant Radiotherapy for Soft Tissue Sarcoma

Ramiz Abu Hijlih¹*, Sara Mheid¹, Fawzi Abuhijla¹, Wafa Asha¹, Issa Mohamad¹, Sameer Yaser², Ahmed Shehadeh³, Samer Abdal³, Abdelatif Almousa² and Samer Salah MD¹

Received: September 11, 2018;   Published: September 20, 2018

DOI: 10.26717/BJSTR.2018.09.001765

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Abstract

Background: It is unknown if the radiologic response after neoadjuvant radiation (RT) in patients with soft tissue sarcoma correlates with the histologic response or disease outcomes. The purpose of this study is to evaluate radiographic and histologic responses in patients who received neoadjuvant RT, and to evaluate the relation between these short-term surrogates.

Patients and Methods: We sought to review consecutive patients with primary localized STS, who were treated with preoperative RT, between 2016 and 2018 at a single institution. All patients were required to have initiated RT with the intention to be followed by curative surgical resection. Data on demographics and disease characteristics were retrospectively collected, the tumor volume (cc) was calculated before and after RT, pathology specimens were reviewed for percent of necrosis and status of surgical margins.

Results: Twenty-three patients with primary localized STS were treated with preoperative radiotherapy followed by surgery. There were 11 extremity (48%), 7 retroperitoneal (30%) and 5 thoracic (22%) tumors. The tumor volume decreased after neoadjuvant RT in 10 cases (43%) to a maximum of 50% (range, -5 to -50%), while in eight patients (35%) the tumor grew in size to a maximum of 40% (range, +10 to +40%). The tumor volume was stable in five patients (22%). Complete resection (R0) was achieved in 18 cases (79%), microscopically involved margins (R1) were observed in 4 (17%), and gross residual (R2) in one patient (4%). The median tumor necrosis was 40%. Five patients (22%) demonstrated complete or near-complete pathologic response (≥ 95% necrosis). Pearson correlation coefficient test revealed no correlation between radiologic and histologic responses (- 0.07). Major wound complication after surgery was observed in four patients (17%).

Conclusion: Radiologic response after neo-adjuvant RT was a poor predictor of pathologic response. Complete and near complete histologic responses seem to be associated with favorable clinical outcomes. Larger studies are needed to test these surrogates in a prospective fashion.

Abbreviations: CT: Computed Tomography; MLS: Myxoid Liposarcoma; MRI: Magnetic Resonance Imaging; IRB: Institutional Review Board; CTV: Clinical Target Volume; PTV: Planning Target Volume; IMRT: Intensity Modulated Radiotherapy; VMAT: Volumetric Modulated Arc Therapy; DFS: Disease Free Survival; OS: Overall Survival

Abstract | Introduction | Materials and Methods | Results | Discussion | Conclusion | References |