Metronomic Chemotherapy After Palliative Radiotherapy in Rare Soft Tissue Sarcomas: An Insight into Radiation Therapy and the Immune Response.

Abstract

Soft tissue sarcomas (STSs) account for less than 1% of the overall human burden of malignant tumors. The intent of treatment in metastatic STSs is palliative and prognosis is dismal. This study aims to evaluate the role of low-dose radiotherapy and low-dose oral metronomic therapy in heavily pretreated metastatic infrequent STSs. This study was conducted in a prospective observational manner in a tertiary care center. A total of 16 cases met the inclusion criteria for enrollment in the study group. The diagnosis of all subtypes of STS was confirmed by histopathology and immunohistochemistry or cytogenetic studies. All the enrolled patients with metastatic STSs who were treated with surgery and two lines of chemotherapy were initially treated with low-dose radiotherapy of 20Gy in 5 fractions or 30Gy in 10 fractions according to the ECOG performance status of the patient. Out of 16 patients, seven patients (43.75%) were treated with 20Gy, 5#, and 9 patients (56.25%) were treated with 30Gy, 10# radiotherapy (RT). Out of 16 patients, four were of malignant fibrohistiocytic sarcoma, three were angiosarcoma, three were malignant phylloides tumor of the breast, two were fibrosarcoma, and one patient from each of the following subtypes inflammatory myofiroblastic tumor, leiomyosarcoma, synovial sarcoma, and dermato fibrosarcoma protuberance. Out of 16 patients, seven (43.75%) had a partial response (PR), nine (56.25%) had stable disease (SD) at 3months, and all the patients had SD at 6months of evaluation. All the patients had enjoyed a better quality of life as compared to their life during injectable chemotherapy. Targeted low-dose radiation and metronomic chemotherapy leads to quantifiable antiangiogeneic effects and immune effects in the local tumor microenvironment, and influences circulating immune mediators and anti-angiogenesis that could potentially help eradicate disease both within and outside the radiation treatment field.