A phase II study of palliative radiotherapy combined with zoledronic acid hydrate for metastatic bone tumour from renal cell carcinoma.

Palliative radiotherapy is the standard of care for bone metastases. However, skeletal-related events, defined as a pathologic fracture, paraplegia, surgery or radiotherapy for local recurrence, or severe pain in previously irradiated bone with radio-resistant histology type still present high incidence. The primary objective of this study was to determine whether zoledronic acid hydrate and palliative radiotherapy could prevent local skeletal-related events.

Eligible patients with bone metastases from renal cell carcinoma were treated with zoledronic acid hydrate every 3 or 4 weeks and concurrent palliative radiotherapy of 30 Gy in 3 Gy fractions. The criteria for radiotherapy were established by the treating physician, but patients with complicated bone metastases (impending pathological fracture or spinal cord compression) which needed immediate surgery were excluded. The primary endpoint was the local skeletal-related event-free survival rate at 1 year.

Twenty-seven patients were included in the study. The median age was 65 (range, 50-84) years. Radiotherapy dose was 30 Gy for all patients except 1 whose radiotherapy was terminated due to brain metastasis progression at 18 Gy. Zoledronic acid hydrate was administered in a median of 12 (range, 0-34) times. The median follow-up period was 12 months and 19 months in patients who were still alive. Of 27 patients in the efficacy analysis, the 1-year local skeletal-related event-free rate was 77.6% (80% confidence interval, 66.2-89.0). Common grade 3 toxicities were hypocalcemia (1 [4%]), sGPT level increase (1 [4%]) and sGOT level increase (1 [4%]). There was no grade 4 or 5 toxicity.

Zoledronic acid hydrate administration and palliative radiotherapy were a well-tolerated and promising treatment reducing skeletal-related events for bone metastases from renal cell carcinoma.

Japanese journal of clinical oncology. 2020 Sep 01 [Epub ahead of print]

Hideyuki Harada, Naoto Shikama, Hitoshi Wada, Nobue Uchida, Miwako Nozaki, Kazushige Hayakawa, Kazunari Yamada, Hisayasu Nagakura, Hirofumi Ogawa, Kazunari Miyazawa, Hirohisa Katagiri, Naoki Nakamura

Division of Radiation Therapy, Radiation and Proton Therapy Center, Shizuoka Cancer Center, Shizuoka, Japan., Department of Radiation Oncology, Graduate School of Medicine, Juntendo University, Tokyo, Japan., Department of Radiation Oncology, Southern TOHOKU Proton Therapy Center, Fukushima, Japan., Department of Radiation Oncology, Tottori University, Tottori, Japan., Dokkyo Medical Unversity, Saitama Medical Center, Saitama, Japan., Department of Radiology and Radiation Oncology, Kitasato University School of Medicine, Kanagawa, Japan., Department of Radiation Oncology, Seirei Mikatahara General Hospital, Shizuoka, Japan., Department of Radiology, KKR Sapporo Medical Center, Hokkaido, Japan., Department of Radiation Oncology, Showa General Hospital, Tokyo, Japan., Division of Orthopedic Oncology, Shizuoka Cancer Center, Shizuoka, Japan., Department of Radiation Oncology, St. Marianna University School of Medicine, Kanagawa, Japan.