Pathologic necrosis following neoadjuvant radiotherapy or chemoradiotherapy is prognostic of poor survival in soft...

Neoadjuvant radiotherapy ± chemotherapy and wide local excision is an accepted management of localized soft tissue sarcomas (STS). Necrosis is prognostic for survival in osteosarcomas, but the significance for STS is undetermined. This study aimed to determine if percent true necrosis, opposed to a combination of necrosis and fibrosis, leads to improved survival in extremity and trunk STS.

From 2000 to 2015, 162 patients with STS were treated with neoadjuvant therapy and resection. Patient and tumor variables were reviewed, and resected specimens underwent pathological assessment. Necrosis was ratiometrically determined. Overall (OS), distant metastasis-free (DMFS), and progression-free survival (PFS) were calculated using Kaplan-Meier estimator. Survival was determined using the Fisher's exact test for univariate analysis (UVA) and logistic regression for multivariate analysis (MVA).

Median follow-up was 4.5 years and median necrosis was 24.97%. Necrosis predicted worse OS, DMFS, and PFS on UVA, and DMFS and PFS on MVA. Necrosis was positively correlated with size and grade. To mitigate the role of size, a sub-analysis of ≥ 10 cm tumors was performed revealing necrosis predicted decreased DMFS and PFS on UVA and MVA. In high-grade tumors, necrosis correlated with decreased DMFS and PFS on UVA. Necrosis did not predict OS in ≥ 10 cm or high-grade tumors.

Our data suggests necrosis may be an additional independent, prognostic variable with increased necrosis predicting a worse prognosis. Necrosis may not be a measure of treatment response and instead suggests more aggressive tumor biology as high-grade, large STS were associated with increased necrosis.