Phase 1/2 trial of single-session stereotactic body radiotherapy for previously unirradiated spinal metastases.

BACKGROUND: In this phase 1/2 study, the authors tested the hypothesis that single-fraction stereotactic body radiotherapy (SBRT) for previously unirradiated spinal metastases is a safe, feasible, and efficacious treatment approach. METHODS: All patients were evaluated by a multidisciplinary team. Spinal magnetic resonance imaging studies were obtained before treatment and at regular intervals to define both target volume and response to treatment. SBRT was delivered to a peripheral dose of 16 to 24 grays in a single fraction while limiting the dose to the spinal cord. Higher doses were used for renal cell histology. The National Cancer Institute Common Toxicity Criteria 2.0 and McCormick neurologic function score were used as toxicity assessment tools. RESULTS: In total, 61 patients who had 63 tumors of the noncervical spine were enrolled and received SBRT between 2005 and 2010 on a prospective, phase 1/2 trial at The University of Texas M. D. Anderson Cancer Center. The mean follow-up was 20 months. The actuarial 18-month imaging local control rate for all patients was 88%, the actuarial 18-month overall survival rate for all patients was 64%, and the median survival for all patients was 30 months. No significant differences in outcomes were noted with respect to tumor histology or SBRT dose. Two patients experienced radiation adverse events (grade 3 or higher). The actuarial rate of 18-month freedom from neurologic deterioration from any cause was 82%. CONCLUSIONS: Data from this phase 1/2 trial supported an expanded indication for SBRT as first-line treatment of spinal metastases in selected patients. The authors concluded that additional studies that can prospectively identify predictive factors for spinal cord toxicity after SBRT are warranted to minimize the incidence of this serious yet rare complication.

Effects of variable placement of superior tangential/supraclavicular match line on dosimetric coverage of level III axilla/axillary apex in patients treated with breast and supraclavicular radiotherapy.

PURPOSE: To determine the differences in dosimetric coverage of the Level III axillary node target as a function of the superior tangential/supraclavicular match line in breast cancer patients undergoing with tangential breast and supraclavicular fossa radiotherapy. METHODS AND MATERIALS: The data from 20 consecutive breast cancer patients who were treated with breast conservation surgery and Level I and II axillary dissection followed by radiotherapy to the undissected Level III axilla/supraclavicular fossa were retrospectively analyzed. The nodal volumes were delineated from the computed tomography simulation data set. Three composite treatment plans were generated for each patient according to the placement of the match line. RESULTS: Coverage of the contoured Level III/axillary apex varied significantly with respect to the ipsilateral clavicular head, depending on the placement of the superior tangential/supraclavicular match line. The mean volume of the Level III/axillary apex covered by the 90% isodose line (45 Gy) was 100% for caudal placement of the match line, significantly greater than the 92% for intermediate placement (bisecting the clavicular head; p = 0.001) and the 68% for cranial placement with respect to the clavicular head (p < 0.001). CONCLUSION: Placement of the superior tangential/supraclavicular match line caudal to the clavicular head results in statistically improved dosimetric coverage of the Level III axilla/axillary apex in breast cancer patients undergoing tangential/supraclavicular radiotherapy.

Field-in-field technique with intrafractionally modulated junction shifts for craniospinal irradiation.

PURPOSE: To plan craniospinal irradiation with "field-in-field" (FIF) homogenization in combination with daily, intrafractional modulation of the field junctions, to minimize the possibility of spinal cord overdose. METHODS AND MATERIALS: Lateral cranial fields and posterior spinal fields were planned using a forward-planned, step-and-shoot FIF technique. Field junctions were automatically modulated and custom-weighted for maximal homogeneity within each treatment fraction. Dose-volume histogram analyses and film dosimetry were used to assess results. RESULTS: Plan inhomogeneity improved with FIF. Planning with daily modulated junction shifts provided consistent dose delivery during each fraction of treatment across the junctions. Modulation minimized the impact of a 5-mm setup error at the junction. Film dosimetry confirmed that no point in the junction exceeded the anticipated dose. CONCLUSIONS: Field-in-field planning and modulated junction shifts improve the homogeneity and consistency of daily dose delivery, simplify treatment, and reduce the impact of setup errors.

Intensity-modulated radiotherapy (IMRT) and conventional three-dimensional conformal radiotherapy for high-grade gliomas: does IMRT increase the integral dose to normal brain?

PURPOSE: To determine whether intensity-modulated radiotherapy (IMRT) treatment increases the total integral dose of nontarget tissue relative to the conventional three-dimensional conformal radiotherapy (3D-CRT) technique for high-grade gliomas. METHODS AND MATERIALS: Twenty patients treated with 3D-CRT for glioblastoma multiforme were selected for a comparative dosimetric evaluation with IMRT. Original target volumes, organs at risk (OAR), and dose-volume constraints were used for replanning with IMRT. Predicted isodose distributions, cumulative dose-volume histograms of target volumes and OAR, normal tissue integral dose, target coverage, dose conformity, and normal tissue sparing with 3D-CRT and IMRT planning were compared. Statistical analyses were performed to determine differences. RESULTS: In all 20 patients, IMRT maintained equivalent target coverage, improved target conformity (conformity index [CI] 95% 1.52 vs. 1.38, p < 0.001), and enabled dose reductions of normal tissues, including brainstem (D(mean) by 19.8% and D(max) by 10.7%), optic chiasm (D(mean) by 25.3% and D(max) by 22.6%), right optic nerve (D(mean) by 37.3% and D(max) by 28.5%), and left optic nerve (D(mean) by 40.6% and D(max) by 36.7%), p < or = 0.01. This was achieved without increasing the total nontarget integral dose by greater than 0.5%. Overall, total integral dose was reduced by 7-10% with IMRT, p < 0.001, without significantly increasing the 0.5-5 Gy low-dose volume. CONCLUSIONS: These results indicate that IMRT treatment for high-grade gliomas allows for improved target conformity, better critical tissue sparing, and importantly does so without increasing integral dose and the volume of normal tissue exposed to low doses of radiation.