Nephron-Sparing Robotic Radiosurgical Therapy for Primary Renal Cell Carcinoma: Single-Institution Experience and Review of the Literature.

PURPOSE: We report our single-institution stereotactic body radiation therapy (SBRT) experience on stage I renal cancer with prospectively collected toxicity and efficacy data. METHODS AND MATERIALS: A total of 21 patients with solitary renal tumors, including 14 surgical candidates who refused surgery (66%), were treated with SBRT. Histologic confirmation was obtained on all patients before treatment; 2 had transitional cell carcinoma and 19 had renal cell carcinoma. The median age was 71 years (range, 58-88). Nearly all patients received 48 Gy in 3 fractions. RESULTS: The median follow-up was 78 months (range, 5-107). At 5 years post treatment, the local tumor control rate was 100%. Tumor size decreased by a median value of 5.3% at 1 year post treatment, 15.6% at 2 years post treatment, and 15.4% at 5 years post treatment. Glomerular filtration rate had decreased by a median value of 1.5% at 1 year post treatment, 7.0% at 2 years post treatment, and 14.2% at 5 years post treatment. Three patients experienced grade 1 toxicity; no other treatment-related adverse effects were reported. CONCLUSIONS: SBRT is a promising noninvasive treatment in the management of primary renal cell carcinoma, with evolving clinical evidence demonstrating encouraging results with respect to local control and toxicity.

Prevention of needle displacement in multifraction high-dose-rate prostate brachytherapy: A prospective volumetric analysis and technical considerations.

PURPOSE: We conducted a prospective study to evaluate needle displacements between prostate high-dose-rate (HDR) brachytherapy fractions and offer technical recommendations to help prevent displacements from the outset. METHODS AND MATERIALS: Planning computed tomography and verification computed tomography scans were obtained at 1-mm slice thickness and prospectively assessed for interfraction needle movement for each fraction of a 2-fraction HDR prostate boost. For both the planning and verification CTs, distances from each needle tip to the centroid of 3 implanted prostate gold seeds were measured. We determined the mean and range of the displacement distances. RESULTS: Thirty-three consecutive patients (66 fractions, 540 needle-pair positions for a total of 1080 needles) were evaluated for changes in the length between the needle tip and centroid displacement. Overall, only 0.2% of the needles had any change greater than 3.5 mm between the needle tip and centroid. The mean amount of displacement was 0.97 mm, with a standard deviation of 0.76 mm. Among the patients, no fraction had more than 1 needle with a variation greater than 3.0 mm. CONCLUSIONS: Needle displacements in HDR prostate brachytherapy have been reported by numerous institutions using various techniques. We report the first study to demonstrate needle displacement of less than 1 mm on average, and we describe our process of care surrounding the implantation.

Preliminary comparison of helical tomotherapy and mixed beams of unmodulated electrons and intensity modulated radiation therapy for treating superficial cancers of the parotid gland and nasal cavity.

BACKGROUND AND PURPOSE: To investigate combining unmodulated electron beams with intensity-modulated radiation therapy to improve dose distributions for superficial head and neck cancers, and to compare mixed beam plans with helical tomotherapy. MATERIALS AND METHODS: Mixed beam and helical tomotherapy dose plans were developed for two patients with parotid gland tumors and two patients with nasal cavity tumors. Mixed beam plans consisted of various weightings of a enface electron beam and IMRT, which was optimized after calculation of the electron dose to compensate for heterogeneity in the electron dose distribution within the target volume. RESULTS: Helical tomotherapy plans showed dose conformity and homogeneity in the target volume that was equal to or better than the mixed beam plans. Electron-only plans tended to show the lowest doses to normal tissues, but with markedly worse dose conformity and homogeneity than in the other plans. However, adding a 20% IMRT dose fraction (i.e., IMRT:electron weighting = 1:4) to the electron plan restored target conformity and homogeneity to values comparable to helical tomotherapy plans, while maintaining lower normal tissue dose. CONCLUSIONS: Mixed beam treatments offer some dosimetric advantages over IMRT or helical tomotherapy for target depths that do not exceed the useful range of the electron beam. Adding a small IMRT component (e.g., IMRT:electron weighting = 1:4) to electron beam plans markedly improved target dose homogeneity and conformity for the cases examined in this study.