PURPOSE: To describe our 3-dimensional conformal planning approaches and report early toxicities with stereotactic body radiation therapy for the management of primary renal cell carcinoma.
METHODS AND MATERIALS: This is an analysis of a phase 1 trial of stereotactic body radiation therapy for primary inoperable renal cell carcinoma. A dose of 42 Gy/3 fractions was prescribed to targets ≥5 cm, whereas for < 5 cm 26 Gy/1 fraction was used. All patients underwent a planning 4-dimensional CT to generate a planning target volume (PTV) from a 5-mm isotropic expansion of the internal target volume. Planning required a minimum of 8 fields prescribing to the minimum isodose surrounding the PTV. Intermediate dose spillage at 50% of the prescription dose (R50%) was measured to describe the dose gradient. Early toxicity (< 6 months) was scored using the Common Terminology Criteria for Adverse Events (v4.0).
RESULTS: From July 2012 to August 2013 a total of 20 patients (median age, 77 years) were recruited into a prospective clinical trial. Eleven patients underwent fractionated treatment and 9 patients a single fraction. For PTV targets < 100 cm3 the median number of beams used was 8 (2 noncoplanar) to achieve an average R50% of 3.7. For PTV targets >100 cm3 the median beam number used was 10 (4 noncoplanar) for an average R50% value of 4.3. The R50% was inversely proportional to decreasing PTV volume (r=-0.62, P=.003) and increasing total beams used (r=-0.51, P=.022). Twelve of 20 patients (60%) suffered grade ≤ 2 early toxicity, whereas 8 of 20 patients (40%) were asymptomatic. Nausea, chest wall pain, and fatigue were the most common toxicities reported.
CONCLUSION: A 3-dimensional conformal planning technique of 8-10 beams can be used to deliver highly tolerable stereotactic ablation to primary kidney targets with minimal early toxicities. Ongoing follow-up is currently in place to assess long-term toxicities and cancer control.
Written by:
Pham D, Thompson A, Kron T, Foroudi F, Kolsky MS, Devereux T, Lim A, Siva S. Are you the author?
Department of Radiotherapy Services, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia; Department of Medical Imaging and Radiation Sciences, Monash University, Melbourne, Victoria, Australia; Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia; Sir Peter MacCallum Department of Oncology, Melbourne University, Melbourne, Victoria, Australia; Department of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.
Reference: Int J Radiat Oncol Biol Phys. 2014 Dec 1;90(5):1061-8.
doi: 10.1016/j.ijrobp.2014.07.043
PubMed Abstract
PMID: 25442039