Sarcoma and Cutaneous Tumors
PV QA 2 - Poster Viewing Q&A 2
Purpose/Objective(s): Soft tissue sarcoma (STS) is a heterogeneous disease composed of many histological subtypes that is treated largely with the same paradigm. Surgery is the primary treatment for localized STS. Peri-operative radiation (RT) and chemotherapy are adjunctive treatments; their use can be tailored by the presence of nodal and/or distant metastases. For patients receiving pre-operative RT, we aimed to determine the impact of time from RT to surgery on survival. Survival and disease outcomes were also evaluated, stratified by histologic subtype, timing of peri-operative RT, and the presence of genetic alterations.
Materials/Methods: We retrospectively reviewed STS patients from 2000-2015 undergoing multimodality management including surgery and RT at a single institution. They were stratified by time from RT to surgery (defined as the end of radiotherapy to the date of resection), receipt of pre- vs post-operative RT by histologic subtype, survival by histologic subtype and genetic aberrations. Actuarial overall survival (OS) and freedom from distant metastases (FDM) were assessed by the Kaplan-Meier method and subgroups compared by log-rank tests.
Results: 302 patients with localized STS were treated with surgery and either pre-operative (n=213) or post-operative (n=89) RT. 78 patients received chemotherapy, given either neoadjuvantly, adjuvantly, or both. On multivariable analysis (MVA), a longer interval from RT to surgery was associated with inferior OS (HR: 1.10 (95% CI 1.02-1.18), p=0.012) in patients who received pre-operative RT. Receiving post-operative RT vs pre-operative RT was associated with a trend towards improved FDM (90% vs 63.6%, p=0.087) and OS (100% vs 72.4%, p=0.078) in leiomyosarcoma patients. This effect of radiation sequencing was not seen in any other histologic subtype (p>0.05). 3-year FDM and OS rates by histologic subtype were: 67.3% and 77.3% for malignant histiocytoma/ pleomorphic sarcomas (n=115), 77.4% and 78.3% for liposarcoma (n=58), 71.5% and 81.8% for leiomyosarcomas (n=37), 75.7% and 85.4% for synovial sarcomas (n=31), 76.3% and 68.8% for fibrosarcomas (n=19), 67.5% and 87.5% for peripheral nerve sheath tumors (n=10). Genetic alternations, specifically DDIT3-gene fusions (n=2), MDM2 amplifications (n=8) or SYT translocations (n=11), did not affect DFM or OS in the univariate setting (p=0.84).
Conclusion: A longer interval between the end of radiation therapy and surgery is an independent predictor of worse overall survival. Post-operative RT may be associated with favorable FDM and OS in leiomyosarcoma compared to pre-operative RT. These findings may help refine treatment decision-making in a highly heterogeneous disease.
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