Pathologic complete response in patients with localized soft tissue sarcoma treated with neoadjuvant therapy and its correlation with clinical outcomes: a systematic review

Soft tissue sarcomas (STS), comprising approximately 1% of adult solid malignancies, are primarily treated with surgery, with the choice of perioperative treatment being a challenging and highly individualized decision. Clinical trials assessing neoadjuvant modalities in STS predominantly use clinical outcomes or radiologic response as endpoints, with pathologic complete response (pCR) not being employed as a designated study endpoint. Our systematic review aimed to assess the rates of pCR in clinical trials of different neoadjuvant modalities for STS and its correlation with patient clinical outcomes. 23 phase I, II and III studies were included, from which data regarding rates of pCR with each treatment, as well as correlation of pCR with clinical outcomes were retrieved. In 16 trials that assessed pCR, the percentage of patients who achieved a pCR ranged from 8 to 58%. Most of these trials did not aim to establish an association between pCR and clinical outcomes. However, among those that did investigate this correlation, a positive association was identified between pCR and both 5-year disease-specific survival (DSS) and 5-year overall survival (OS). While pCR serves as a crucial marker guiding treatment decisions in other neoplasms like triple negative breast cancer and urothelial cancer, it is not yet used in a similar setting for STS. Our findings indicate variability in patients achieving pCR across different neoadjuvant treatments for STS and a possible positive correlation with patient outcomes. Consequently, we propose considering pCR as a surrogate endpoint in future prospective trials for STS.