## 4 Discussion  
We conducted a retrospective analysis of HPV-positive OPSCC patients treated with definitive or postoperative CRT at a large NCI-designated comprehensive cancer center (COH) main campus and compared it to selected institutional satellite sites with availability of dedicated radiation therapy facilities staffed with COH faculty with primary endpoint of OS and secondary endpoints including treatment response, feeding tube dependency, and weight loss throughout treatment and 6 months post-treatment. Our analysis is the first to compare patient outcomes in a comprehensive NCI designated cancer center and its affiliated satellite sites. COH main site and satellite sites demonstrated OS rates consistent with already published favorable survival rates in OPSCC treated with multimodality therapy approach [7,19], while median OS at \(\sim\)12 years was not reached (Figure 2A). No significant difference in two-year (94% vs. 84%, \(p=0.12\)) and five-year (92% vs. 84%, \(p=0.23\)) PFS was observed between the main campus and the satellite sites (Table 2). Our data did not align with previously reported analyses of head and neck cancer outcomes in academic centers versus community sites that demonstrated superior survival rates in patients treated at academic institutions [16,18]. One major difference between our study and the previously mentioned analyses [16,18] relates to the fact that our patients were treated under an umbrella institution, COH, regardless of treatment center location. Overall, our institution takes strides to standardize patient care across all sites by the longstanding establishment of weekly radiation oncology web rounds dedicated to reviewing all radiation treatment plans at any COH site. Our outcomes are possible because of these efforts of treatment compliance between main and satellite centers where there is some uniformity in dose delivery, nodal coverage based on primary site and nodal disease distribution, overall treatment volumes, and establishedguidelines for treatment planning. Furthermore, the medical oncologists at the COH satellites are part of the medical oncology main department and are required to attend quarterly retreats with the oncologists at main campus. Regarding differences in the choice of concurrent systemic therapy, the oncologists at the main campus site strongly favored cisplatin as the chemotherapy agent of choice (78%), whereas satellite site medical oncologists equally favored cisplatin (48%) and cetuximab (48%) when treating their patients (\(p\) = 0.001). Considering the different distribution of tumor size between the two groups of patients with main campus seeing a higher number of T3-4 disease (19 [38%] vs. six [14%], \(p\) = 0.008) (Table 1 and Figure 1B), the choice of cisplatin-based therapy could have been influenced by the more advanced stage of disease at presentation. In addition, these patients were treated before the completion and publication of The Radiation Therapy Oncology Group (RTOG) 1016 clinical trial that compared systemic therapy agent cisplatin versus cetuximab, a monoclonal antibody against EGFR, in HPV-positive OPSCC, and reported superior PFS with cisplatin over cetuximab (78% vs. 67%, \(p\) < 0.001) [20]. A small subset of patients underwent treatment with induction chemotherapy followed by CRT in our analysis (five at the main campus vs. two patients at the satellite sites, \(p\) = 0.31). While the use of induction chemotherapy in head and neck cancers is controversial, a recent phase II trial demonstrated feasibility of different induction regimens stratified by disease risk in locally advanced head and neck squamous cell carcinoma [21]. In our study, chemotherapy dose reductions occurred among patients who were treated with high-dose cisplatin, underscoring the heavy burden of side effects that this treatment carries and the need for continuous monitoring by the medical oncologist to avoid permanent renal and neurological impairment effect on quality of life and survival outcomes.