Volume changes in soft tissue sarcomas during preoperative radiotherapy of extremities evaluated using cone-beam CT

Abstract

ObjectiveThe objective of this study is to quantify volume changes in the gross target volume (GTV) during preoperative radiotherapy for extremity soft tissue sarcomas (ESTS).MethodsTwenty-seven patients with ESTS, treated with preoperative radiotherapy, were included in this study. Weekly cone-beam CT scans acquired for setup correction were used for GTV delineation in order to quantify volume changes over the course of treatment. Age, anatomical location, tumour type and tumour volume were evaluated as predictive factors for volume changes. Finally, the optimal time point for adaptive intervention was quantified.ResultsA GTV increase to a maximum of 28 % occurred in five patients. Thirteen patients showed no change and nine patients (all diagnosed with myxoid liposarcoma (MLS)) showed a GTV decrease to a maximum of 57 % of the GTV volume at start of treatment. In the multivariate analysis, only the relative volume change for tumour type was significant (p = 0.001). The optimal time point for adaptive intervention in non-MLS patients was the first week and for MLS patients the third week.ConclusionsVolume changes were quantified during preoperative RT of ESTS. Volume decrease was observed only in MLS patients. Individualised treatment resulting in plan adaptations could result in a clinically useful volume reduction for MLS patients.

A phase I study on the combination of neoadjuvant radiotherapy plus pazopanib in patients with locally advanced soft tissue sarcoma of the extremities

“…This observation underlines the heterogeneity in sensitivity to pazopanib across different EsTs subtypes. Like differences in outcome to pazopanib, differences in radiosensitivity among EsTs histological subtypes have also been demonstrated [8,20,21] further stressing the importance of stratification in EsTs studies. Future clinical trials combining 50 Gy RT with 800 mg pazopanib in EsTs should not only include assays and image modalities providing insight in the underlying (radio)biology, but should also include early stopping rules for futility and unacceptable toxicity, with an emphasis on hepatotoxicity.…”

“…Myxoid liposarcomas (MLs), with their dense vasculature, regress markedly during preopRT. some suggest that the RT target may not so much be the sarcoma cells but the supplying vasculature [20,21]. In this subtype, de-escalating the preopRT dose is currently under investigation (ClinicalTrials.…”

Preoperative radiotherapy for extremity soft tissue sarcoma; past, present and future perspectives on dose fractionation regimens and combined modality strategies

“…Finally, reports for myxoid liposarcomas (MLS) have consistently shown exquisite radiation sensitivity, characterized by a marked tumor volume reduction during radiotherapy and excellent local control rates [32–34]. After surgery, the resection specimens frequently show a fibrotic myxoid stroma containing, nonlipogenic, hyalinized structures.…”

Hypofractionated Radiotherapy in Locally Advanced Myxoid Liposarcomas of Extremities or Trunk Wall: Results of a Single-Arm Prospective Clinical Trial

“…MLPS, when compared to other STS subtypes, shows higher sensitivity to RT. There are reports of the substantial decrease in the volume of lesions and also histological features of response to radiation treatment such as induction of adipogenesis [11,12]. Furthermore, in MLPS patients treated with the aforementioned hypofractionated RT regimen, pathological response to therapy was observed despite the very short gap between the RT completion and surgery, i.e., between two and seven days [13].…”