Background: To review a single institutional experience of the Radiation Therapy Oncology Group (RTOG) 8502 “QUAD shot” regimen using volumetric modulated arc radiotherapy (VMAT) for incurable head and neck cancer (HNC). Methods: Thirty-four consecutive patients with HNC were treated with at least one cycle of the RTOG 8502 regimen. Treatment plans included the use of VMAT with 6 MV photons generated by a linear accelerator. Two daily fractions of 3.7 Gy were delivered with an interval of at least 6 h for 2 consecutive days, totaling 14.8 Gy over 4 fractions. This was repeated every 3–4 weeks for a total of three cycles. No concurrent systemic therapy was performed. Results: The number of completed cycles was 1 in 6 (18%) patients, 2 in 5 (15%), and 3 in 23 (68%). Tumor response was achieved in 29 (85%) patients and symptom relief in 20 (77%) of 26 patients. Overall response (tumor response or symptom relief) was achieved in 32 (94%) patients. All patients who received 2 or more treatment cycles achieved overall response. Median overall survival (OS) was 5.7 months. Multivariate analysis revealed that completion of all three treatment cycles was significantly associated with better OS (P = 0.002). Grade 2 toxicity was observed in four (12%) patients, but no acute Grade ≥ 3 or late toxicity was observed. Conclusions: The RTOG 8502 “QUAD shot” regimen using VMAT is effective for incurable HNC with highly reduced toxicity. Treatment with multiple cycles is recommended for better treatment response and/or survival.

Purpose: To analyze the efficacy of adaptive radiotherapy (ART) for glioblastoma. Methods: Sixty-one glioblastoma patients who received ART were prospectively evaluated. The initial clinical target volume (CTVinitial) was represented by T2 hyperintensity on postoperative MRIs (pre-RT MRI [MRIpre])plus 10 mm. The initial planning target volume (PTVinitial) was the CTVinitial plus a 5-mm margin. The PTVinitial received 40 Gy. An MRI and a second planning CT were performed during radiotherapy (MRImid). Two types of boost CTVs (the resection cavity and residual tumor on enhanced T1-weighted MRI plus 10 mm) were created based on the MRIpre and MRImid (CTVboost-pre and -mid). The boost PTV (PTVboost) was the CTVboost plus 5 mm. Two types of boost plans (fixed and adaptive boost plans in the first and second planning CT, respectively) of 20 Gy were created. The PTV based on the post-RT MRI (PTVboost-post) was created, and the dose-volume histograms of the PTVboost-post in the fixed and adaptive boost plans were compared. Additionally, the conformity indices (CIs) of the fixed and adaptive boost plans were compared. Results: The median V95 of the PTVboost-post of the fixed and adaptive boost plans (V95pre and V95mid) were 95.6% and 98.3%, respectively (P < 0.01). The median V95pre and V95mid of patients after gross total resection (GTR) were 97.4% and 98.8%, respectively (P = 0.41); in contrast, the median values of patients after non-GTR were 91.9% and 98.2%, respectively (P < 0.01). The median CIs of the fixed and adaptive boost plans in all patients were 1.45 and 1.47, respectively (P = 0.31). The median CIs of the fixed and adaptive boost plans in patients after GTR were 1.61 and 1.48, respectively (P = 0.01); in contrast, those in patients after non-GTR were 1.36 and 1.44, respectively (P = 0.13). Conclusion: ART for glioblastoma improved the target coverage and dose reduction for the normal brain. By analyzing the results according to the resection rate, we can expect a decrease in normal brain dose in patients with GTR and an increase in coverage in those with partial resection or biopsy.

Supporting data defining the selection criteria of level VIIb for inclusion in the target volume in radiotherapy (RT) planning are insufficient. We evaluated the prevalence of level VIIb retro-styl...

Background: Glioblastoma (GBM) is an aggressive primary brain tumor with a high recurrence rate despite multimodal treatment approaches. Adaptive radiation therapy (ART) involves adjusting the treatment plan based on tumor and resection cavity changes during radiotherapy, potentially improving treatment precision while reducing radiation exposure to normal brain tissue. However, the clinical outcomes and recurrence patterns associated with ART remain unclear. We aimed to evaluate the efficacy of ART for GBM treatment, focusing on survival outcomes and recurrence patterns. Methods: We retrospectively analyzed a prospectively collected cohort of 59 patients with pathologically confirmed GBM who received postoperative three-dimensional conformal radiotherapy (3D-CRT)–based ART between April 2015 and November 2018. Mid-treatment magnetic resonance imaging was performed after delivery of 34–36 Gy. Based on these images, an offline single-time-point ART boost plan was generated to accommodate changes in tumor size and the resection cavity. Radiotherapy consisted of 40 Gy in 20 fractions to the initial target, followed by a 20 Gy boost in f10 fractions (total 60 Gy in 30 fractions over six weeks). Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan–Meier method. Recurrence patterns were classified by the spatial relationship between recurrent tumor volume and the 95% isodose line. Results: During a median follow-up period of 19.2 (range, 2.1–81.6) months, 36 patients (61.0%) experienced tumor recurrence, and 32 (54.2%) died. The 1- and 2-year OS rates were 93.9% and 54.6%, respectively, with a median OS of 26.6 months. The 6- and 12-month PFS rates were 71.1% and 46.1%, respectively, with a median PFS of 10.5 months. Central recurrence was the most common pattern (29 patients, 78%), followed by distant (5 patients, 14%) and in-field recurrences (3 patients, 8%). Marginal recurrence was not observed. No cases of grade 2 or higher radiation necrosis were observed, and only two cases of grade 1 radiation necrosis were identified. Conclusions: ART for GBM is associated with favorable survival outcomes and low toxicity. ART does not increase the risk of marginal recurrence, and the incidence of radiation necrosis is low. Further studies are required to optimize ART protocols to maximize their clinical benefits.