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  • resazurin Introduction Bone metastases are a common

    2019-05-10

    Introduction Bone metastases are a common manifestation of cancer [1]. Most patients present with pain and impaired mobility, while others can develop complications such as pathological fractures and resazurin of the spinal cord or cauda equina [2]. Many randomized studies have been conducted to determine if a dose response exists for pain relief from palliative radiation therapy in patients with painful bone metastases. The most recent systematic review of these trials conclude the equivalency of single fraction (SF) and multiple fraction (MF) treatments for pain relief from “uncomplicated” bone metastases, though the meaning of the term is not explicitly stated in most of the examined studies [3]. The United States national guidelines published by the American Society of Radiation Oncology and the American College of Radiology suggest that there are no differences between SF and MF dosing in palliative treatment for bone metastases [2,4], although definitions distinguishing between complicated and uncomplicated bone metastases were not consistently provided. In practice, most radiation oncologists consider bone metastases causing pathologic fractures or compression of the spinal cord and cauda equina to be complicated. Some also consider those with associated soft tissue components or those within weight bearing bones at high risk of fracture to be complicated as well, but operational definitions vary among practice settings. A clearer definition of “uncomplicated bone metastases” is required to determine the patient population in which the results of the prospective randomized trials apply. Whereas a workgroup or committee could be established to explore this issue, the translation of existing data to practice patterns necessitates a comprehensive evaluation of the completed trials. So, the purpose of the current study was to examine the inclusion and exclusion criteria of the randomized studies as described in the recent systematic review [5–29], thereby clearly defining the characteristics of the patient population in which a SF is equivalent to MF for the palliation of “uncomplicated” bone metastases.
    Materials and methods Only fully published trials from the systematic review were included in the analysis, and therefore abstract by Kirkbride et al. [13] was omitted. Study by Amouzegar-Hashemi et al. [24] and abstract by Haddad et al. [29] used the same trial, and therefore the former was used in the analysis. Study by Steenland et al. [26] and follow-up by van der Linden et al. [18] used the same trial, and therefore the former was used in the analysis. Study by Kaasa et al. [28] and its follow-up by Sande et al. [27] also used the same trial, and therefore the former was used in the analysis. The methods sections of 21 studies comparing SF to MF course of radiation therapy for painful bone metastases out of 25 studies included in the most recent systematic review of bone metastases treatment were examined by PMC, EW and NT for their patient inclusion and exclusion criteria [5–29].
    Results The inclusion and exclusion criteria of the 21 studies are listed in Table 1. All 21 studies included patients with bone metastases, whereas all but one study specified painful resazurin bone metastases. Thirteen of the 21 studies required cytological or histological evidence of malignancy as part of the inclusion criteria, and 9 of these studies required radiographic evidence of bone metastases. Five of such studies did not specify the method of imaging, 1 specified X-ray, 2 specified X-ray or bone scan, and 1 specified X-ray, bone scan, CT or MRI. Only 2 studies limited accrual to patients with a previously specified primary tumor location, and only 2 studies included patients with pain deemed to have resulted from neuropathic pain.
    Discussion A systematic review showed that SF radiotherapy resulted in equivalent pain relief to MF courses of radiation therapy for patients with uncomplicated painful bone metastases [3]. However, in order to apply the findings of this paper to the appropriate patient population, a description for the term “uncomplicated bone metastases” is preferred. Based upon an analysis of inclusion/exclusion criteria for 21 prospective randomized studies, we suggest the following working definition: uncomplicated bone metastases are those unassociated with impending or existing pathologic fracture or existing spinal cord compression or cauda equina compression.