Long-term clinical outcomes of stereotactic radiotherapy for bilateral vestibular schwannomas in neurofibromatosis type 2 patients.

PURPOSE: The evidence for treating patients with neurofibromatosis 2-related vestibular schwannoma (VS-NF2) using hypofractionated stereotactic radiation therapy (HSRT) is limited. This study aimed to investigate clinical outcomes in patients with VS-NF2 treated with Robotic HSRT. METHODS: We retrospectively analyzed 25 NF2 patients with 48 VSs who were treated using Robotic HSRT at Ramathibodi Hospital from January 2009 to January 2020. RESULTS: Median follow-up was 98 months (range, 24-155 months). Median tumor volume was 2.3 cm3 (range, 0.4-28.3 cm3). Median prescribed dose was 18 Gy (range, 18-25 Gy) in three fractions (range, 3-5). The 5- and 10-year local control rates were 87% and 80%, respectively. The 5- and 10-year hearing preservation rates were 59% and 35%, respectively. Three patients developed new symptoms associated with transient volume expansion after treatment: hydrocephalus in one, facial weakness in one, and ataxia in one. No patient developed worsening of trigeminal nerve function. No histologically confirmed of radiation induced malignancy was reported in the study. CONCLUSIONS: Robotic HSRT demonstrated excellent long-term tumor control with a low non-auditory complication rate in patients with VS-NF2. However, preservation of hearing remains a major concern.

Clinical and Dosimetric Factors Predicting Grade ≥2 Radiation Pneumonitis After Postoperative Radiotherapy for Patients With Non-Small Cell Lung Carcinoma.

PURPOSE: To identify clinical and dosimetric factors that would predict grade ≥2 radiation pneumonitis (RP) for patients undergoing postoperative radiation therapy (PORT) for non-small cell lung cancer (NSCLC); and to use the factors identified to generate a predictive model to quantify risk of RP in such patients. METHODS AND MATERIALS: We retrospectively reviewed radiation therapy, radiographic, and clinical data from 199 patients who had received PORT, with or without chemotherapy, for NSCLC. Potential associations between dosimetric and clinical factors and RP were evaluated in univariate and multivariate Cox regression hazard models and competing risk analysis. Kaplan-Meier analysis was used to estimate overall survival and the cumulative incidence of RP, and receiver operating characteristic curve analysis to identify cutpoints for variables found to influence RP risk. The endpoint was grade ≥2 RP (symptomatic, requiring steroids or limiting instrumental activities of daily living). RESULTS: Thirty-seven patients (19%) developed grade ≥2 RP. Patient-related factors, type of surgery or chemotherapy, and radiation therapy-related factors were not associated with grade ≥2 RP; only lung V10 > 30% and lung V20 > 20% predicted grade ≥2 RP. Risk groupings were as follows: high risk, V10 > 30% and V20 > 20% (24 of 72 patients, 33%); intermediate risk, V10 > 30% and V20 ≤ 20% or V10 ≤ 30% and V20 > 20% (6 of 26 patients, 23%); and low risk, V10 ≤ 30% and V20 ≤ 20% (6 of 101 patients, 6%) (P < .0001). In a subgroup analysis of patients who had had lobectomy, corresponding incidences of RP were as follows: high risk, 20 of 59 (34%); intermediate risk, 5 of 22 (23%); and low risk, 6 of 70 (9%) (P = .001). CONCLUSIONS: The lung dose-volume variables V10 and V20 predicted risk of grade ≥2 RP among patients who underwent PORT for NSCLC.

Placement of an absorbable rectal hydrogel spacer in patients undergoing low-dose-rate brachytherapy with palladium-103.

PURPOSE: Rates of rectal toxicity after low-dose-rate (LDR) brachytherapy for prostate cancer are dependent on rectal dose, which is associated with rectal distance from prostate and implanted seeds. Placement of a hydrogel spacer between the prostate and rectum has proven to reduce the volume of the rectum exposed to higher radiation dose levels in the setting of external beam radiotherapy. We present our findings with placing a rectal hydrogel spacer in patients following LDR brachytherapy, and we further assess the impact of this placement on dosimetry and acute rectal toxicity. METHODS AND MATERIALS: Between January 2016 and April 2017, 74 patients had placement of a hydrogel spacer, immediately following a Pd-103 seed-implant procedure. Brachytherapy was delivered as follows: as a monotherapy to 26 (35%) patients; as part of planned combination therapy with external beam radiotherapy to 40 (54%) patients; or as a salvage monotherapy to eight (11%) patients. Postoperative MRI was used to assess separation achieved with rectal spacer. Acute toxicity was assessed retrospectively using Radiation Oncology Therapy Group radiation toxicity grading system. Rectal dosimetry was compared with a consecutive cohort of 136 patients treated with seed implantation at our institution without a spacer, using a 2-tailed paired Student's t test (p < 0.05 for statistical significance). RESULTS: On average, 11.2-mm (SD 3.3) separation was achieved between the prostate and the rectum. The resultant mean rectal volume receiving 100% of prescribed dose (V100%), dose to 1 cc of rectum (D1cc), and dose to 2 cc of rectum (D2cc) were 0 (SD 0.05 cc), 25.3% (SD 12.7), and 20.5% (SD 9.9), respectively. All rectal dosimetric parameters improved significantly for the cohort with spacer placement as compared with the nonspacer cohort. Mean prostate volume, prostate V100 and dose to 90% of gland (D90) were 29.3 cc (SD 12.4), 94.0% (SD 3.81), and 112.4% (SD 12.0), respectively. Urethral D20, D5cc, and D1cc were 122.0% (SD 17.27), 133.8% (SD 22.8), and 144.0% (SD 25.4), respectively. After completing all treatments, at the time of first the followup, 7 patients reported acute rectal toxicity-6 experiencing Grade 1 rectal discomfort and 1 (with preexisting hemorrhoids) experiencing Grade 1 bleeding. CONCLUSIONS: Injection of rectal spacer is feasible in the post-LDR brachytherapy setting and reduces dose to the rectum with minimal toxicity. Prostate and urethral dosimetries do not appear to be affected by the placement of a spacer. Further studies with long-term followup are warranted to assess the impact on reduction of late rectal toxicity.

A relative increase in circulating platelets following chemoradiation predicts for poor survival of patients with glioblastoma.

BACKGROUND: Thrombocytosis is triggered by and promotes tumor growth. The relationship between the change in circulating platelets after chemoradiation therapy (CRT) or adjuvant temozolomide (TMZ) and survival in glioblastoma remains unclear. We hypothesized that an increase in platelets after these treatments would be predictive of a shorter survival. METHODS: We retrospectively reviewed data on 122 patients with newly diagnosed, pathologically proven glioblastoma who had been treated with surgery, followed by CRT and adjuvant TMZ, from 2007 to 2016. The association between the changes in blood count levels and survival was analyzed by the log-rank test. To adjust for confounding, we performed a multivariate analysis using known prognostic co-variates. RESULTS: Patients were dichotomized on the basis of the relative change in platelets after CRT from the baseline: ≤30% increase, low (n = 101) vs >30% increase, high (n = 12). The median survival for high vs. low platelets were 11 vs 28 months (p = 0.0062). No significant survival differences were observed on the basis of platelet changes during adjuvant TMZ. Similarly, changes in lymphocyte counts were not significantly prognostic. On multivariate analysis, MGMT, performance status, and an increase in platelets after CRT were significantly associated with survival (HR for platelets, 4.5; 95% confidence interval, 1.6-12.6). CONCLUSIONS: Increased platelet counts after CRT are predictive of poor survival in glioblastoma. The effect is platelet specific and does not reflect bone marrow changes, as lymphocyte changes were not significantly prognostic. These results suggest an interaction between platelets and tumor aggressiveness. Thus, platelets serve as a novel, minimally invasive liquid biopsy for predicting outcome.