The treatment of primary and metastatic renal cell carcinoma (RCC) with stereotactic body radiation therapy (SBRT) and stereotactic radiosurgery (SRS)

Abstract

14572 Background: RCC is often regarded as a radio-resistant tumor. However, brain metastases from RCC have been successful treated with SRS. Therefore, metastases to extra-cranial sites may be treated with similar success using stereotactic body radiation therapy (SBRT), where image-guidance allows for the delivery of precise high dose radiation in a few fractions. We report our experience with SRS/SBRT in the management of primary and metastatic RCC. Methods: The image-guided Novalis radiation therapy system was used. Thirty patients with brain metastases were treated with SRS (16–22 Gy in a single fraction). Five of these patients underwent resection of their metastatic lesions after SRS and their pathology were reviewed. Twenty patients with extra-cranial metastatic lesions (orbits, head and neck, lung, mediatinum, sternum, clavicle, scapula, humerus, rib, spine, abdomen) and 2 patients with biopsy proven primary RCC (not surgical candidates), were treated with SBRT (24–32 Gy in 3–4 fractions over 1–2 weeks). All patients were immobilized in body cast and image-guidance was used for all fractions. 4D-CT was utilized in the treatment planning to assess tumor motion. Results: Of the 30 patients who received SRS to brain metastases, 25 showed decreasing or stable lesion size. Five patients showed an increase in size and underwent resection. Their pathology revealed necrosis in >99% of the specimen, with no viable RCC. Nineteen patients who received SBRT to extra-cranial metastases achieved symptom relief. One patient had local progression, yielding a local control rate of 95%. In the 2 patients with primary RCC, tumor size remained unchanged but their pain improved, and their renal function was unchanged post SBRT. There was no significant treatment related side-effect. Conclusions: Precise high dose radiation can cause significant tumor cell death in “radio-resistant” metastases from RCC. It also offers excellent local control and symptom palliation, without significant toxicity. Therefore, SBRT may represent a novel non-invasive, nephron-sparing option for the treatment of primary RCC as well as extra-cranial metastatic RCC. A prospective clinical trial using SBRT for primary and metastatic RCC is on-going. No significant financial relationships to disclose.