Abscopal Effect of Radiotherapy in Imatinib-resistant Dermatofibrosarcoma Protuberans

Abstract

Local tumor control and symptom relief have been the major advantage of radiotherapy in clinical practice. In the past years, the systemic anti-tumor effect of radiotherapy, also known as the abscopal effect, has been reported with limited studies. With the advent of immunotherapy, the frequency of the abscopal effect has increased in patients who receive sequential treatment with radiotherapy and immunotherapy or patients who receive radiotherapy after acquiring resistance to immunotherapy. A novel cancer treatment modality, such as molecular targeted therapy, has been associated with the immune response within the tumor but its systemic anti-tumor effect, when combined with radiotherapy, is yet to be documented. There have been few studies to date assessing the immunological effects of imatinib on tumors; however, the mechanism of tumor regression or resistance acquisition is poorly understood. We present a 56-year-old male diagnosed with dermatofibrosarcoma protuberans (DFSP) who developed resistance to imatinib after five months of treatment. Following subsequent local radiotherapy to the primary tumor, he had complete clinical remission of the primary and metastatic lesions.

Dermatofibrosarcoma Protuberans: Update on the Diagnosis and Treatment

“…Multiple studies have shown that DFSP is a radio-responsive tumor and adjuvant radiation therapy is effective to control tumor growth and reduce the incidence of postoperative recurrence [102][103][104][105][106]. A retrospective analysis of 53 DFSP patients treated with surgery and either preoperative or postoperative radiation therapy in the MD Anderson Cancer Center showed disease-free survival rates of 98% and 93% at 5 and 10 years, respectively [105].…”

A Patient-Level Data Meta-analysis of the Abscopal Effect

“…50 studies (n=55 subjects) published from 1954 -2019 met inclusion criteria and were used. 23,24,[33][34][35][36][37][38][39][40][41][42]25,[43][44][45][46][47][48][49][50][51][52]26,[53][54][55][56][57][58][59][60][61][62]27,[63][64][65][66][67][68][69][70][71][72]28,[73][74][75][76][77][29][30][31][32] The median patient age was 65 years (interquartile range, IQR: 57-70); 34 (62%) males and 21 (...…”

“…(1) Prior treatment courses were as follows (treatments in this phase were not mutually exclusive): 9 (16%) had radiotherapy, 28,33,38,41,46,53,64,73,75 26 (47%) had surgery, 23,24,45,48,[53][54][55]61,[67][68][69][70]28,71,[75][76][77]31,33,[38][39][40][41][42] 23 (42%) had chemotherapy, 23,27,42,48,49,51,53,56,60,64,68,69,28,[71][72][73]31,32,35,36,38,40,41 ...…”

“…28,29,69,71,73,77,32,39,41,45,53,54,66,68 (2) During the course of treatment leading up to an abscopal response, 34 (62%) patients received radiotherapy alone, 24,32,49,[51][52][53][55][56][57][58][59][60]33,63,65,[67][68][69][70]72,74,75,77,34,36,37,40,43,45,46 5 (9.1%) underwent surgery with radiotherapy, 25,27,28,35,54 4 (7.3%) received chemotherapy with radiotherapy, 28,39,45,62 and 11 (20%) received immunotherapy with radiotherapy. 29,31,73,38,41,42,54,61,66,…”

Recurrent Dermatofibrosarcoma Protuberans of the Head and Neck: a Case Series

“…In the literature, tumors with close or positive surgical margins, recurrent tumors, metastatic tumors, and large unresectable tumors are treated with radiation therapy and systemic therapy as adjuvant treatment modalities [ 5 ]…”