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Objectives A pooled analysis of PORTEC-1 & 2 identified substantial lymphovascular space invasion (LVSI) in 4.8% of patients, which predicted for pelvic recurrence, distant metastasis, and overall survival. Our institution implemented the PORTEC three-tier system of LVSI reporting (absent, focal, or substantial). We aimed to quantify the incidence of substantial LVSI in a North American population and to correlate extent of LVSI with lymph node (LN) involvement. Methods A retrospective review was conducted on patients with clinically uterine-confined, endometrioid type endometrial cancer who underwent surgical staging and were found to have pT1a-b disease. Binary logistic regression was used to assess predictors of LN involvement (defined as ITC, micrometastases, or macrometastases). Results In total, 438 patients with pT1a-b disease were identified. In the overall cohort and in the subset meeting PORTEC-1 inclusion criteria (n = 195), no LVSI was present in 67.4% and 50.8%; focal LVSI was present in 16.7% and 24.1%; and substantial LVSI was present in 16.0% and 25.1%, respectively. Among patients who underwent surgical LN assessment (79.2%, n = 347), LNs were involved in 3.3% without LVSI, 7.5% with focal LVSI (OR 2.4), and 15.2% with substantial LVSI (OR 5.3) (p = .005), with a similar trend in the PORTEC-1 cohort. Extent of LVSI correlated with disease burden in LN metastases. Conclusion Our incidence of substantial LVSI was three to five times higher than reported by PORTEC and correlated with LN involvement. This questions the reproducibility of the three-tier LVSI reporting system and emphasizes the need for multi-institutional data outside PORTEC for confirmation of our findings.

OBJECTIVE: It has been postulated that treatment outcomes are similar between transoral robotic surgery (TORS) and definitive chemoradiation (CRT) for oropharyngeal squamous cell carcinomas (OPSCC). We compared oncologic and quality of life (QOL) outcomes between definitive CRT and definitive TORS. MATERIALS AND METHODS: An observational comparison study was performed on 92 patients treated with TORS ± adjuvant therapy and 46 patients treated with definitive CRT between July 2005 and January 2016. The Kaplan Meier method was used for survival analyses, and the Mann-Whitney test was used to compare QOL scores between groups. RESULTS: All patients had T0-T2 and N0-N2 disease, although CRT patients had higher clinical staging (p < 0.001). HPV+ disease was present in 79% (n = 73) of TORS patients and 91% (n = 19) of tested CRT patients. Median follow-up was 22.1 months (range: 0.33–83.4). There were no significant differences in locoregional control or overall survival between CRT and TORS groups. Definitive TORS resulted in better saliva-related QOL than definitive CRT at 1, 6, 12, and 24 months (p < 0.001, p = 0.025, p = 0.017, p = 0.011). Among TORS patients, adjuvant therapy was associated with worse QOL in the saliva domain at 6, 12, and 24 months (p < 0.001, p < 0.001, p = 0.007), and taste domain at 6 and 12 months (p = 0.067, p = 0.008). CONCLUSION: Definitive CRT and definitive TORS offer similar rates of locoregional control, overall survival, and disease-free survival in patients with early stage OPSCC. TORS resulted in significantly better short and long-term saliva-related QOL, whereas adjuvant therapy was associated with worse saliva and taste-related QOL compared to TORS alone.

PURPOSE: To correlate carotid dose and risk of carotid blowout syndrome (CBOS) after stereotactic body radiation therapy (SBRT), hypothesizing that carotid dose does not correlate with CBOS. METHODS AND MATERIALS: We retrospectively reviewed 186 patients with recurrent, previously irradiated head and neck cancer treated between January 2008 and March 2013. Patients treated early in our experience with incomplete dosimetry were excluded from analysis (n = 111). A total of 75 patients were identified, providing 150 carotid arteries for analysis. Median follow-up was 8 months (range, 1–91 months) for all patients, and 37 months for surviving patients (range, 31–91 months). Patients were treated with linear accelerator–based SBRT to a median dose up to 44 Gy (range, 40–50 Gy) in 5 fractions delivered on a twice-weekly basis. Concurrent cetuximab was used in 63 patients (84%). The bilateral common, internal, and external carotid arteries were delineated 2 cm above and below the planning target volume. The maximum dose to 0.1 cm(3) (D(0.1cc)), 1 cm(3) (D(1cc)), and 2 cm(3) (D(2cc)) of the carotid and the mean carotid dose from SBRT were recorded and analyzed for association with carotid bleeding events, using binary logistic regression. RESULTS: Median reirradiation interval was 20 months (range, 3–423 months), and median prior radiation dose was 70 Gy (range, 52.5–140 Gy). Sixteen patients (21.3%) received more than 1 course of SBRT, and the cumulative carotid doses from fused summary plans were recorded. The overall median D(0.1cc,) D(1cc,) D(2cc), and mean carotid doses were 40.8 Gy (interquartile range [IQR], 21.6–47.6 Gy), 26.8 Gy (IQR, 14.1–42.1 Gy), 15.4 Gy (IQR, 8.4–32.7 Gy), and 15.0 Gy (IQR, 8.9–23.3 Gy), respectively. There were a total of 4 bleeding events (5.3%): 2 patients (2.7%) had mucosal bleeds that resolved after embolization of carotid branches, and 2 patients (2.7%) died from complications of CBOS. In the 2 patients with CBOS the D(0.1cc) was 48.4 Gy and 47.6 Gy, respectively. There was no significant association between bleeding events and D(1cc) (P = .280), D(2cc) (P = .571), or mean dose (P = .568). There was a trend toward increased risk of bleeding and D(0.1cc) (P = .080). CONCLUSIONS: These results demonstrate a low risk of bleeding after reirradiation with SBRT when 5 fractions are delivered on nonconsecutive days, even when tumor is completely encasing the carotid artery. Although limited by the low number of events, no significant association was found between dose-volume parameters and the risk of carotid bleeding. No CBOS was noted when D(0.1cc) was

full 3D motion of CTV. A prototype Hexamotion 6D motion platform was used in the validation study. It was used to simulate patient specific tumor motion pattern. The platform moves with input at every 20 ms. Three different VMAT plans were delivered with movement and compared with static measurements. In addition, each of the VMAT plans was also delivered with a sinusoidal motion pattern with peak to peak amplitudes of 1, 2 and 3 cm and target period of 3.5 seconds. All the measurements were performed using a 3D dosimeter with each of the VMAT plan irradiated 3 times, each irradiation starting at a random point in respiratory cycle. The average monitor units (MU) per plan was 2910 MU, the average number of segments per plan was 191 with 2 MU being minimum MU per control point. Results: All static plans passed with local gamma at 99.6% and 96.8% at 3%, 3mm and 2%, 2mm threshold criteria respectively. The average passing rate for local gamma with patient specific tumor motion was 96.7 % and 90% at 3%, 3mm and 2%, 2mm threshold criteria respectively. The average passing rate at 3% 3mm threshold criteria was 97.2% with 2cm peak to peak sinusoidal motion in the superior-inferior (SI) direction and 76.7% for the 3 cm peak to peak SI amplitude sinusoidal motion pattern. Conclusion: Dosimetry measurements using 3D and Hexamotion 6D platform indicate that single arc VMAT plans can be accurately delivered and that interplay effect is not significant for target amplitudes less than or equal to 2cm. The interplay effect is low because of the larger averaging effect associated with increased dose per fraction (1000 cGy) delivered during at least 90 breathing cycles. Author Disclosure: R. Varadhan: None. S. Way: None. C. Overbeck: None. K. Nisi: None.