IMPORTANCEThe optimal approach for treatment deescalation in human papillomavirus (HPV)-related oropharyngeal squamous cell carcinomas (OPSCCs) is unknown.OBJECTIVE To assess a primary radiotherapy (RT) approach vs a primary transoral surgical (TOS) approach in treatment deescalation for HPV-related OPSCC. DESIGN, SETTING, AND PARTICIPANTSThis international, multicenter, open-label parallel-group phase 2 randomized clinical trial was conducted at 9 tertiary academic cancer centers in Canada and Australia and enrolled patients with T1-T2N0-2 p16-positive OPSCC between February 13, 2018, and November 17, 2020. Patients had up to 3 years of follow-up.INTERVENTIONS Primary RT (consisting of 60 Gy of RT with concurrent weekly cisplatin in node-positive patients) vs TOS and neck dissection (ND) (with adjuvant reduced-dose RT depending on pathologic findings). MAIN OUTCOMES AND MEASURESThe primary end point was overall survival (OS) compared with a historical control. Secondary end points included progression-free survival (PFS), quality of life, and toxic effects. RESULTSOverall, 61 patients were randomized (30 [49.2%] in the RT arm and 31 [50.8%] in the TOS and ND arm; median [IQR] age, 61.9 [57.2-67.9] years; 8 women [13.6%] and 51 men [86.4%]; 31 [50.8%] never smoked). The trial began in February 2018, and accrual was halted in November 2020 because of excessive toxic effects in the TOS and ND arm. Median follow-up was 17 months (IQR, 15-20 months). For the OS end point, there were 3 death events, all in the TOS and ND arm, including the 2 treatment-related deaths (0.7 and 4.3 months after randomization, respectively) and 1 of myocardial infarction at 8.5 months. There were 4 events for the PFS end point, also all in the TOS and ND arm, which included the 3 mortality events and 1 local recurrence. Thus, the OS and PFS data remained immature. Grade 2 to 5 toxic effects occurred in 20 patients (67%) in the RT arm and 22 (71%) in the TOS and ND arm. Mean (SD) MD Anderson Dysphagia Inventory scores at 1 year were similar between arms (85.7 [15.6] and 84.7 [14.5], respectively). CONCLUSIONS AND RELEVANCEIn this randomized clinical trial, TOS was associated with an unacceptable risk of grade 5 toxic effects, but patients in both trial arms achieved good swallowing outcomes at 1 year. Long-term follow-up is required to assess OS and PFS outcomes.

One year of adjuvant trastuzumab is considered the standard treatment for patients with HER2 positive breast cancer. However, a shorter duration of trastuzumab may be associated with reduced costs and side effects. Results from randomized trials with diverse non-inferiority margins comparing one year to a shorter duration of adjuvant trastuzumab are not consistent and have not been systematically reviewed using a non-inferiority meta-analysis approach. We conducted a systematic review and meta-analysis of randomized trials to assess whether a shorter duration of adjuvant trastuzumab was non-inferior to one year of treatment or not. The non-inferiority margin for the meta-analysis was pre-defined as the median of the margins of all the trials included. Data of 11,376 patients from 5 trials were analyzed. Non-inferiority margins in included studies varied from 1.15 to 1.53 with median of 1.29 for HR of DFS. A shorter duration of trastuzumab was non-inferior to one year of therapy for DFS (HR 1.13, 95%CI 1.03–1.24) but inconclusive for OS (HR 1.14, 95%CI 1.00–1.30). In a subgroup analysis for DFS outcome, shorter therapy was non-inferior in patients with ER positive disease (HR 1.10, 95%CI 0.95–1.28) and those with sequential therapy (HR 0.97, 95%CI 0.75–1.27) and when the duration of treatment was 6 months (HR 1.09, 95%CI 0.98–1.22). Although a shorter duration of adjuvant trastuzumab was non-inferior to one year of therapy for DFS in patients with HER2 positive breast cancer based on our HR margin of 1.29, any benefit of a shorter duration comes at a loss of efficacy with an increase in absolute risk up to 3.9% for 5 year DFS. Whether the potential increased risk is clinically acceptable for the benefits of a shorter duration remains debatable.

522 Background: One year of adjuvant trastuzumab (T) remains the standard treatment for patients with HER2 positive breast cancer. Results from randomized trials with diverse non-inferiority margins comparing one year to a shorter duration of adjuvant T were not consistent, particularly with the PERSEPHONE and the final PHARE and Short-HER trials’ results. Our objective was to conduct a systematic review and meta-analysis of randomized trials in patients with HER2 positive breast cancer to assess whether a shorter duration of adjuvant T was non-inferior to one year of treatment. Methods: PubMed, EMBASE and The Cochrane Library were searched for eligible randomized trials. Hazard ratios (HR) for disease free and overall survival (DFS, OS) were weighted using generic inverse variance and pooled in a meta-analysis using random-effects models. The median of non-inferiority margins derived from each trial was calculated to set a non-inferiority margin of 1.29 for the pooled analysis. Subgroup analyses compared survival outcomes by estrogen receptor (ER) status, nodal status, length and timing of trastuzumab treatment. Results: Data of 11,376 patients from 5 trials were analyzed. A shorter duration of T was non-inferior to one year of therapy for DFS (HR 1.13, 95%CI 1.03-1.24) but worse for OS (HR 1.16, 95%CI 1.01-1.32). In addition, the non-inferiority for DFS was met for patients with ER positive disease (HR 1.1, 95%CI 0.95-1.28) and patients treated with 6 months (HR 1.09, 95%CI 0.98-1.22) or sequential T (HR 0.97, 95%CI 0.75-1.27). Conversely, the non-inferiority for DFS was not met for patients with ER negative disease (HR 1.22, 95%CI 1.06-1.41), patients treated with 9 weeks (HR 1.26, 95%CI 1.02-1.55) or concomitant T (HR 1.25, 95%CI 1.07-1.45) and patients with node negative (HR 1.12, 95% 0.93-1.35) or positive (HR 1.16, 95%CI 0.99-1.36) disease. Conclusions: Within the limitations of the available data and the different non-inferiority margins used in randomized trials, a shorter duration of adjuvant T is non-inferior to one year of therapy for DFS in patients with HER2 positive breast cancer, particularly in patients with ER positive disease. Further trials with appropriately chosen non-inferiority margins are needed to confirm the optimal duration of T in patients with low-risk disease.

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Background: Patients with resected oral cavity squamous cell carcinoma (OCSCC) are often treated with adjuvant radiation (RT) ± concomitant chemotherapy based on pathological findings. Standard RT volumes include all surgically dissected areas, including the tumour bed and dissected neck. RT has significant acute and long-term toxicities including odynophagia, dysphagia, dermatitis and fibrosis. The goal of this study is to assess the rate of regional failure with omission of radiation to the surgically dissected pathologically node negative (pN0) hemi-neck(s) compared to historical control, and to compare oncologic outcomes, toxicity, and quality of life (QoL) profiles between standard RT volumes and omission of RT to the pN0 neck. Methods: This is a multicentre phase II study randomizing 90 patients with T1-4 N0-2 OCSCC with at least one pN0 hemi-neck in a 1:2 ratio between standard RT volumes and omission of RT to the pN0 hemi-neck(s). Patients will be stratified based on overall nodal status (nodal involvement vs. no nodal involvement) and use of concurrent chemotherapy. The primary endpoint is regional failure in the pN0 hemi-neck(s); we hypothesize that a 2-year regional recurrence of 20% or less will be achieved. Secondary endpoints include overall and progression-free survival, local recurrence, rate of salvage therapy, toxicity and QoL. Discussion: This study will provide an assessment of omission of RT to the dissected pN0 hemi-neck(s) on oncologic outcomes, QoL and toxicity. Results will inform the design of future definitive phase III trials.