Factors Influencing Pain Reduction: Bone Metastases From Renal Cell Carcinoma (RCC) Treated With Radiation Therapy

Abstract

The efficacy of palliative radiation therapy for RCC is not well documented in the literature. The purpose of this study is to evaluate, retrospectively, the outcomes, especially concerning pain reduction with radiation therapy in the management of bone metastases from RCC. Conventional three-dimensional conformal radiation therapy (3D-CRT) was used in the treatment of patients with bone metastases from RCC at our institution from 2010-2012. The median age was 67 years (range, 45-85 years). The median dose administered was 36Gy (range, 30-50 Gy). In patients, 3 Gy daily fractional dose was employed. Effectiveness of radiation therapy with respect to tumor control and palliation of pain was assessed using numerical rating scale (NRS) and the amount of analgesia. Survival was calculated using Kaplan-Meier analysis, with a statistically difference tested by log-rank test. A P value of less than .05 was considered to be statistically significant. Thirty-five patients treated with a total of 63 metastatic sites. A median follow-up time was 6.9 months (range,1.2-46.6 months). A 1-year overall survival was 50.6%. Radiation was delivered to 24 vertebral, 12 pelvic and other metastatic lesions including ribs and extremities. The average size of metastatic tumor of bone was 37 mm measured by the longest tumor diameter using axial CT or MRI images. Two of metastatic sites (femur and humerus) got a fracture after the radiation therapy within a year. Forty-seven percent of metastatic sites treated with radiation therapy alone had experienced durable pain relief more than one year without increasing the amount of analgesia. Among them, patients with the long interval (>3 years) measured from the date of the initial diagnosis of RCC to the first day of radiation therapy had statistically significant pain relief (P = .001). Other factors, such as sex, age, tumor size and tumor location, were not significant for alleviating pain. Patients with the long interval from the date of the initial diagnosis of RCC to the first day of radiation therapy of bone metastasis had a favorable pain relief with a statistically significant difference (P = .001). Therefore, patients with well controlled RCC by surgery and/or targeted agents have a greater possibility of gaining durable pain relief by radiation therapy to their bone metastases from RCC.