Spine stereotactic radiosurgery for metastatic sarcoma: patterns of failure and radiation treatment volume considerations.

OBJECTIVE Given the relatively lower radiosensitivity of sarcomas and the locally infiltrative patterns of spread, the authors sought to investigate spine stereotactic radiosurgery (SSRS) outcomes for metastatic sarcomas and to analyze patterns of failure. METHODS The records of 48 patients with 66 sarcoma spinal metastases consecutively treated with SSRS between 2002 and 2013 were reviewed. The Kaplan-Meier method was used to estimate rates of overall survival (OS) and local control (LC). Local recurrences were categorized as occurring infield (within the 95% isodose line [IDL]), marginally (between the 20% and 95% IDLs), or out of field. RESULTS Median follow-up time was 19 months (range 1-121 months), and median age was 53 years (range 17-85 years). The most commonly treated histology was leiomyosarcoma (42%). Approximately two-thirds of the patients were treated with definitive SSRS (44 [67%]) versus postoperatively (22 [33%]). The actuarial 1-year OS and LC rates were 67% and 81%, respectively. Eighteen patients had a local relapse, which was more significantly associated with postoperative SSRS (p = 0.04). On multivariate modeling, receipt of postoperative SSRS neared significance for poorer LC (p = 0.06, subhazard ratio [SHR] 2.33), while only 2 covariates emerged as significantly correlated with LC: 1) biological equivalent dose (BED) > 48 Gy (vs BED ≤ 48 Gy, p = 0.006, SHR 0.21) and 2) single vertebral body involvement (vs multiple bodies, p = 0.03, SHR 0.27). Of the 18 local recurrences, 14 (78%) occurred at the margin, and while the majority of these cases relapsed within the epidural space, 4 relapsed within the paraspinal soft tissue. In addition, 1 relapse occurred out of field. Finally, the most common acute toxicity was fatigue (15 cases), with few late toxicities (4 insufficiency fractures, 3 neuropathies). CONCLUSIONS For metastatic sarcomas, SSRS provides durable tumor control with minimal toxicity. High-dose single-fraction regimens offer optimal LC, and given the infiltrative nature of sarcomas, when paraspinal soft tissues are involved, larger treatment volumes may be warranted.

Outcomes for Spine Stereotactic Body Radiation Therapy and an Analysis of Predictors of Local Recurrence.

PURPOSE: To investigate local control, survival outcomes, and predictors of local relapse for patients treated with spine stereotactic body radiation therapy. METHODS AND MATERIALS: We reviewed the records of 332 spinal metastases consecutively treated with stereotactic body radiation therapy between 2002 and 2012. The median follow-up for all living patients was 33 months (range, 0-111 months). Endpoints were overall survival and local control (LC); recurrences were classified as either in-field or marginal. RESULTS: The 1-year actuarial LC and overall survival rates were 88% and 64%, respectively. Patients with local relapses had poorer dosimetric coverage of the gross tumor volume (GTV) compared with patients without recurrence (minimum dose [Dmin] biologically equivalent dose [BED] 23.9 vs 35.1 Gy, P<.001; D98 BED 41.8 vs 48.1 Gy, P=.001; D95 BED 47.2 vs 50.5 Gy, P=.004). Furthermore, patients with marginal recurrences had poorer prescription coverage of the GTV (86% vs 93%, P=.01) compared with those with in-field recurrences, potentially because of more upfront spinal canal disease (78% vs 24%, P=.001). Using a Cox regression univariate analysis, patients with a GTV BED Dmin ≥33.4 Gy (median dose) (equivalent to 14 Gy in 1 fraction) had a significantly higher 1-year LC rate (94% vs 80%, P=.001) compared with patients with a lower GTV BED Dmin; this factor was the only significant variable on multivariate Cox analysis associated with LC (P=.001, hazard ratio 0.29, 95% confidence interval 0.14-0.60) and also was the only variable significant in a separate competing risk multivariate model (P=.001, hazard ratio 0.30, 95% confidence interval 0.15-0.62). CONCLUSIONS: Stereotactic body radiation therapy offers durable control for spinal metastases, but there is a subset of patients that recur locally. Patients with local relapse had significantly poorer tumor coverage, which was likely attributable to treatment planning directives that prioritized the spinal cord constraints over tumor coverage. When possible, we recommend maintaining a GTV Dmin above 14 Gy in 1 fraction and 21 Gy in 3 fractions.

Incidence and predictors of severe acute esophagitis and subsequent esophageal stricture in patients treated with accelerated hyperfractionated chemoradiation for limited-stage small cell lung cancer.

PURPOSE: Clinical and dosimetric predictors of severe (grade 3 or greater) acute esophageal toxicity and subsequent esophageal dilation were explored in patients with limited-stage small cell lung cancer treated with accelerated hyperfractionated chemoradiation. METHODS AND MATERIALS: A total of 130 patients were identified who were treated to 45 Gy in 1.5-Gy twice-daily fractions with concurrent platinum-based chemotherapy between 2000 and 2009. Data on clinical, disease-related, and treatment-related variables were collected. Patients with percutaneous endoscopic gastrostomy tube insertion or intravenous hydration because of poor oral intake were designated as having acute grade 3 esophagitis. Univariate and multivariate analyses that associated treatment characteristics with esophagitis were assessed via logistic regression, and optimal cut points were identified with recursive partitioning analysis. RESULTS: Twenty-five patients developed severe acute esophagitis, at a rate of 26% (18/69) in patients treated with earlier 3-dimensional conformal radiation therapy techniques and 11.5% (7/61) in patients treated with intensity modulated radiation therapy techniques and omission of elective nodal irradiation. The incidence of esophageal stricture was 6% overall (8 of 128 eligible) but 26% (6/23) among those who experienced prior grade 3 acute esophagitis and 2% (2/105) among those with acute esophagitis less than or equal to grade 2. Significant multivariate predictors of acute esophagitis were mean dose and volume of esophagus receiving at least 5% to 35% of the prescribed dose (V5 to V40). Patients with V5 ≥ 74% had a 44.4% risk of severe acute esophagitis (12/27) versus 12.6% (13/103) among those with V5 < 74%. V45 was the only dosimetric predictor for esophageal stricture, with 13.7% of patients in whom V45 was ≥37.5% requiring subsequent dilation. CONCLUSIONS: Modern radiation techniques are associated with a lower frequency of severe acute esophagitis than previous paradigms. The proportion of esophagus receiving low- to moderate-range doses (mean, V5 through V40) predicts acute esophagitis, whereas the proportion of esophagus that receives high doses (V45) predicts the development of esophageal stricture that requires dilation. Patients who develop grade 3 acute esophagitis are at significant risk for subsequent esophageal stricture, whereas those with acute esophagitis of grade 2 or less display minimal risk.

Generalizable class solutions for treatment planning of spinal stereotactic body radiation therapy.

PURPOSE: Spinal stereotactic body radiation therapy (SBRT) continues to emerge as an effective therapeutic approach to spinal metastases; however, treatment planning and delivery remain resource intensive at many centers, which may hamper efficient implementation in clinical practice. We sought to develop a generalizable class solution approach for spinal SBRT treatment planning that would allow confidence that a given plan provides optimal target coverage, reduce integral dose, and maximize planning efficiency. METHODS AND MATERIALS: We examined 91 patients treated with spinal SBRT at our institution. Treatment plans were categorized by lesion location, clinical target volume (CTV) configuration, and dose fractionation scheme, and then analyzed to determine the technically achievable dose gradient. A radial cord expansion was subtracted from the CTV to yield a planning CTV (pCTV) construct for plan evaluation. We reviewed the treatment plans with respect to target coverage, dose gradient, integral dose, conformality, and maximum cord dose to select the best plans and develop a set of class solutions. RESULTS: The class solution technique generated plans that maintained target coverage and improved conformality (1.2-fold increase in the 95% van't Riet Conformation Number describing the conformality of a reference dose to the target) while reducing normal tissue integral dose (1.3-fold decrease in the volume receiving 4 Gy (V(4Gy)) and machine output (19% monitor unit (MU) reduction). In trials of planning efficiency, the class solution technique reduced treatment planning time by 30% to 60% and MUs required by ∼20%: an effect independent of prior planning experience. CONCLUSIONS: We have developed a set of class solutions for spinal SBRT that incorporate a pCTV metric for plan evaluation while yielding dosimetrically superior treatment plans with increased planning efficiency. Our technique thus allows for efficient, reproducible, and high-quality spinal SBRT treatment planning.

Radiation for Hodgkin's lymphoma in young female patients: a new technique to avoid the breasts and decrease the dose to the heart.

PURPOSE: To demonstrate how, in young female patients with Hodgkin's lymphoma, using an inclined board technique can further decrease the volume of breasts and heart in the treatment field. METHODS AND MATERIALS: An inclined board was constructed with the ability to mount an Aquaplast face mask, a Vacu-Lock, and a hip stopper. Eight female patients with early-stage Hodgkin's lymphoma were planned and compared using the conventional flat position and the inclined board position. All patients on the inclined board were planned with 90° degree table position and 15° gantry angle rotation to compensate for the beam divergence resulting from the patient's position on the inclined board. Dose-volume histograms were generated, as well as the mean V30 and V5 of both breasts and heart using both treatment positions. RESULTS: The mean value of V30 of the right breast, left breast, and heart decreased from 3%, 3%, and 13%, respectively, using the flat position to 0, 0.4%, and 5%, respectively, using the inclined board. The mean value of V5 of the right breast, left breast, and heart decreased from 6%, 13%, and 36%, respectively, using the flat position to 2%, 8%, and 29%, respectively, using the inclined board. CONCLUSIONS: Compared with conventional flat positioning, this simple device and technique allows better sparing of the breasts and the heart while maintaining comparable target coverage and total lung dose.

Beam path toxicities to non-target structures during intensity-modulated radiation therapy for head and neck cancer.

BACKGROUND: Intensity-modulated radiation therapy (IMRT) beams traverse nontarget normal structures not irradiated during three-dimensional conformal RT (3D-CRT) for head and neck cancer (HNC). This study estimates the doses and toxicities to nontarget structures during IMRT. MATERIALS AND METHODS: Oropharyngeal cancer IMRT and 3D-CRT cases were reviewed. Dose-volume histograms (DVH) were used to evaluate radiation dose to the lip, cochlea, brainstem, occipital scalp, and segments of the mandible. Toxicity rates were compared for 3D-CRT, IMRT alone, or IMRT with concurrent cisplatin. Descriptive statistics and exploratory recursive partitioning analysis were used to estimate dose "breakpoints" associated with observed toxicities. RESULTS: A total of 160 patients were evaluated for toxicity; 60 had detailed DVH evaluation and 15 had 3D-CRT plan comparison. Comparing IMRT with 3D-CRT, there was significant (p 36 Gy, occipital scalp dose >30 Gy, and anterior mandible dose >34 Gy, respectively. CONCLUSIONS: Dose reduction to specified structures during IMRT implies an increased beam path dose to alternate nontarget structures that may result in clinical toxicities that were uncommon with previous, less conformal approaches. These findings have implications for IMRT treatment planning and research, toxicity assessment, and multidisciplinary patient management.