Prognostic relevance of the mitotic count and the amount of viable tumour after neoadjuvant chemotherapy for primary, localised, high-grade soft tissue sarcoma

Background: We sought to examine whether mitotic count (MC) and the amount of viable tumour (VT) following neoadjuvant systemic chemotherapy (SC) for primary, localised, high-grade soft tissue sarcoma (STS) correlate with prognosis. Methods: Retrospective analysis of 57 patients who underwent SC involving a combination of an anthracycline and an alkylating agent, followed by surgical resection between 2001 and 2011. Results: The amount of VT after chemotherapy was significantly associated with disease-specific survival (DSS) and event-free survival (EFS). Patients with <10% VT had a DSS of 94% at 5 years, compared with 61% for patients with >= 10% VT (P = 0.033); EFS was 75%, compared with 48% (P = 0.030). Patients with an MC of >= 20/10 high power fields (HPF) after chemotherapy had a significantly lower DSS (33% vs 84% at 5 years, P<0.001) and EFS (40% vs 63% at 5 years, P = 0.019) than patients with an MC of <20/10 HPF. Conclusions: The MC and the amount of VT after neoadjuvant therapy for primary, localised, high-grade STS appear to correlate with prognosis. If these results are validated prospectively, then they could provide a rational for the design of neoadjuvant treatment modification/escalation studies, analogue to the EURAMOS-1 trial for bone sarcomas.