[26] Pathologic Response to Neoadjuvant Radiotherapy (NRT) as Potential Prognostic Factors in Soft Tissue Sarcomas (STS)

Jason C Chang, Meena Bedi, David L Stockman, Dian Wang, Eduardo V Zambrano. Medical College of Wisconsin, Milwaukee, WI

Background: This study aims to elucidate the prognostic value of pathologic response to NRT in STS and its correlation to RECIST criteria and survival outcomes (SO).
Design: 84 patients aged 19-92 years (mean, 57 years) who underwent resection for STS after NRT were analyzed, including 36 patients who also received neoadjuvant chemotherapy (NCT). Pathologic response was assessed by scoring % of viable tumor, necrosis, fibrosis, and other stromal changes. Other pathologic (tumor size, histologic type, tumor grade, margin status) and clinical parameters (age, sex, location, radiologic response by changes in maximal tumor diameter and RECIST criteria, and SO) were obtained.
Results: Mean % of viable tumor, necrosis, fibrosis, and other stromal changes was 30.8%, 22.2%, 41.2%, and 5.8%, respectively. Pre-NRT and post-NRT MRI results available in 50 patients showed median % change in maximal tumor diameter of 1.4% (range, -60.2 to +55.7%). By RECIST criteria: 8 patients had progressive disease, 37 had stable disease, and 5 had partial response. Tumors that decreased in maximal diameter post-RT exhibited less necrosis (16 ± 4% vs. 36 ± 7%, p=0.015) and more fibrosis (53 ± 5% vs. 23 ± 6%, p=0.001) than tumors that increased in maximal diameter. Comparable findings were found when pathologic response was analyzed with respect to RECIST criteria. Tumors with >80% fibrosis were associated with better SO than tumors with moderate (10-80%) or minimal fibrosis (<10%) (p=0.003, overall survival). Tumors with >5% necrosis were associated with worse SO. Intermediate-grade tumors exhibited higher degree of viable tumor (45 ± 8% vs. 27 ± 3%, p=0.014) and lower degree of necrosis (4 ± 1% vs. 27 ± 3%, p=0.001) compared to high-grade tumors. Tumors <10cm showed higher degree of viable tumor (37 ± 4% vs. 20 ± 4%, p=0.007) and lower degree of necrosis (14 ± 3% vs. 34 ± 5%, p=0.007) than tumors >10cm. No difference in pathologic response was found for tumor type, location, depth, or NCT.
Conclusions: Percent fibrosis showed strong correlation with radiologic response. In contrast, % viable tumor and necrosis showed correlation with inherent aggressiveness of STS. High % fibrosis and low % necrosis were correlated with better OS, and may complement the RECIST criteria in prognosticating patients with STS. We propose incorporating % fibrosis in addition to viable tumor and necrosis as an independent prognostic factor in evaluating post-NRT STS specimens.
Category: Bone & Soft Tissue

Monday, March 19, 2012 1:00 PM

Poster Session II # 38, Monday Afternoon

 

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