Analysis of PET parameters predicting response to radiotherapy for myeloid sarcoma

Abstract

Purpose Positron-emission tomography (PET)-CT has recently been used for diagnostic imaging and radiotherapy for myeloid sarcoma, but there is little research on predicting the response of radiotherapy. The aim of this study was to analyze the association between PET-CT variables and the response to radiotherapy in patients with myeloid sarcoma. Materials and methods This study was conducted in myeloid sarcoma patients who received radiotherapy and PET-CT before and after radiotherapy. The response to radiotherapy was evaluated based on the European Organization for Research and Treatment of Cancer PET response criteria, and binary regression analysis was performed to assess the factors predicting reductions in the maximum standardized uptake value (SUVmax). Results Twenty-seven sites in 12 patients were included in the study. Complete metabolic responses were seen in 24 patients after radiotherapy, a partial metabolic response in one, and progressive metabolic disease in two patients. The prescribed dose of more than 3000 cGy10 was significantly greater in the treatment control group (P = 0.024). In binary logistic regression analysis predicting reductions in the SUVmax of more than 70% after radiotherapy, the pretreatment SUVmax (≥ 7.5) and further chemotherapy after radiotherapy showed significant differences in univariate and multivariate analyses. Conclusion Good metabolic responses (complete or partial) to radiotherapy were achieved in 92.6% of the myeloid sarcoma patients. Radiation doses < 3000 cGy10 and increased SUVmax were related to treatment failure and high SUVmax before radiotherapy was a factor influencing SUVmax reduction. Further large-scale studies are needed.

PET/CT in leukemia: utility and future directions

“…Some studies have focused on the prognostic value of the [ 18 F]FDG PET/CT findings in patients with leukemia; the prognostic significance of extramedullary involvement in leukemia is still being investigated [42]. A total of 12 patients with myeloid sarcoma who received radiotherapy were assessed by [ 18 F]FDG PET/CT before and after treatment [103]. In those patients, high pretreatment SUVmax was related to treatment failure.…”

“…In those patients, high pretreatment SUVmax was related to treatment failure. However, the sample size was small, and further studies in this field are, therefore warranted [103]. Zhao et al .…”

Myeloid Sarcoma: A Primer for Radiologists

“…Furthermore, the authors noted that there were no significant toxicities associated with the treatment. 58 A review of 135 lesions in 12 patients by Choi et al 59 assessed the predictive value of FDG-PET/CT parameters in predicting response to radiotherapy. They found that treatment failed more often when biologically effective dose was low and when SUVmax increased after intervention.…”

“…Interestingly, the observed posttreatment decreases in SUVmax did not seem to be related to radiation site, irradiated volume, or dose. 59 Despite the apparent efficacy and advantages of FDG-PET/CT imaging in detecting MS, it is still recommended to order CT and MRI imaging when extramedullary disease is suspected. 37…”