RADICAL CARBON-ION RT FOR UNRESECTABLE THORACOABDOMINAL SOFT TISSUE SARCOMAS: EFFICACY AND SAFETY
MO-0945
Abstract
RADICAL CARBON-ION RT FOR UNRESECTABLE THORACOABDOMINAL SOFT TISSUE SARCOMAS: EFFICACY AND SAFETY
Authors: Sofia Paola Bianchi1, Viviana Vitolo2, Amelia Barcellini2, Maria Rosaria Fiore2, Agnieszka Chalaszczyk2, Angelica Ghirelli2, Stefania Russo2, Giulia Fontana2, Claudia Sangalli3, Mario Ciocca2, Ester Orlandi2
1University of Milan Bicocca - Department of Radiation Oncology, Monza, National Center of Oncological Hadrontherapy, (CNAO), Clinical Departement, Pavia, Italy; 2National Center of Oncological Hadrontherapy, (CNAO), Clinical Departement, Pavia, Italy; 3Fondazione IRCCS Istituto Nazionale dei Tumori, Department of Radiotherapy, Milan, Italy
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Purpose or Objective
Poor outcomes have been reported with conventional photon-based radiotherapy (RT) for soft tissue sarcomas (STS) deemed unfit for surgery. This retrospective study aimed to evaluate the preliminary results of carbon ion radiotherapy (CIRT) in patients with STS treated with radical intent.
Material and Methods
Data from consecutive patients treated with CIRT from January 2014 to December 2021 for a new diagnosis or a recurrence of unresectable STS were retrospectively collected. Patients were classified as highly radioresistant sarcoma and conventionally radioresistant ones according to the radiosensitivity index previously published. The endpoints of this study were: 5- years local recurrence-free survival (LRFS), the 3 and 5-years overall survival (OS) and acute/late toxicity rates. Actuarial survival outcomes were evaluated using the Kaplan-Meier method. Any correlation between histological type, GTV volume and LRFS was tested using Wilcoxon rank test. Statistical significance was defined as p-value < 0.05. Acute and late toxicities were scored according to the Common Terminology Criteria for Adverse Events (CTCAE) v5.0.C.
Results
A total of 24 patients with a median age of 52 (range, 13-79) underwent radical CIRT. Eleven (46%) of the analyzed patients were treated for the primary disease and 13 (54%) at time of recurrence. 13 (54%) were males and 11 (46%) were females. None of the patients received previous irradiation at CIRT-target. CIRT was delivered for a thoracic localization in 14 (58%) cases and for abdominal in 10 (42%). The most frequent histology was liposarcoma (20%) followed by leiomyosarcoma (13%). There were 15 (63%) highly radioresistant and 9 (37%) conventionally radioresistant tumors. Median GTV was 263 cc (range 14-3603). Eleven patients (44%) received at least one line of chemotherapy before CIRT. The median prescription dose was 64 Gy(RBE) (range 50.4-76.8), with a median dose per fraction of 3.5 Gy(RBE) (range 3-4.8). After a median follow-up of 31 months (range 1-100), 10 patients (41.6%) experienced an in-field recurrence (local recurrence) and the 5-year LRFS rate was 33.1% (95% CI: 14.0%-77.9%). The radioresistant histology (p=0.7) and the GTV (p = 0.93) were not related with LRFS.
The 3-year and 5-year OS was 86% (95% CI: 73.4%-100%) and 72.0% (95% CI: 55.2%-93.8%) (Fig1). GTV volume was not significantly correlated with OS (p = 0.15). With regards to toxicity, no patients needed treatment interruption; the most common acute tocixities were G2 pain and G2 erythema while the most frequent late toxicity was G2 peripheral neuropathy. No G≥3 toxicities were reported.
Conclusion
CIRT appeared a safe non-invasive option treatment for unresectable STS, but clinical trials with a longer follow-up and larger cohort are necessary to evaluate the effectiveness and late toxicity.