## 2 Materials and Methods
### Statistical Considerations  
The primary analysis of this retrospective study design is to determine the differences in outcomes of OPSCC patients treated at COH Cancer Center main campus versus selected COH-associated satellite sites. Before carrying out inferential statistical procedures, exploratory data analysis was performed. Patient characteristics, including age, gender, race, smoking status, stage at diagnosis, cancer site, and p16 status by immunohistochemistry (IHC), and treatment variables, including chemotherapy agent selected, and dose reduction or interruption, and treatment responses were summarized using descriptive statistics. For continuous variables, means/medians, standard deviations, range and for categorical variables, patient counts, and percentages were provided by cancer center sites (Tables 1 and 2). Two sample mean/proportion tests (one-sided/two-sided) were performed for quantitative variables. To test homogeneity (equivalent to testing independence) between the main campus and the COH-associated satellite cancer center sites grouped by categorical patient characteristics and treatment outcomes, [PERSON]'s chi-square test was performed. [PERSON]'s exact test was performed as an alternative where the expected cell counts were small (less than 5). PEG Tube replacement and feeding tube dependency were also compared between two groups (sites).  
\begin{table}
\begin{tabular}{c c c c c} \hline  & & **Main Campus (\(n\) = 50)** & **Satellite Sites (\(n\) = 44)** & \(p\)**-Value** \\  & & \(n\), \% & \(n\), \% & \(p\)**-Value** \\ \hline Age median & & 58 & 61 & \\ Gender & Female & 10 (20) & 5 (11) & \(p\) = 0.25 \\  & Male & 40 (80) & 39 (89) & \\ Vital Status & Alive & 44 (88) & 43 (98) & \(p\) = 0.12 \\  & Deceased & 6 (12) & 1 (2) & \\ Race & Caucasian & 38 (76) & 32 (73) & \(p\) = 0.08 \\  & African American & 1 (2) & 1 (2) & \\  & Asian & 8 (16) & 3 (7) & \\  & Native American & 1 (2) & 0 (0) & \\  & Other/Unknown & 2 (4) & 8 (18) & \\ Smoking status & Never & 25 (50) & 22 (50) & \(p\) = 1.00 \\  & Former/Current & 25 (50) & 22 (5) & \\ AJCC 7 th Edition Stage & I & 0 (0) & 0 (0) & \(p\) = 0.24 \\  & II & 2 (4) & 2 (5) & \\  & III & 5 (10) & 9 (20) & \\  & IV & 43 (86) & 33 (75) & \\ T stage & T0–2 & 31 (62) & 38 (86) & \(p\) = 0.008 \\  & T3–4 & 19 (38) & 6 (14) & \\ N stage & N0–2a & 14 (28) & 19 (43) & \(p\) = 0.124 \\  & N2b-N3 & 36 (72) & 25 (57) & \\ M stage & M0 & 50 (00) & 44 (100) & \\  & M1 & 0 (0) & 0 (0) & \\ Cancer site & Tonsil & 17 (34) & 25 (57) & \(p\) = 0.06 \\  & Base of Tongue & 29 (58) & 15 (34) & \\  & Oropharynx, NOS & 4 (8) & 4 (9) & \\ P16 status & Positive & 42 (84) & 30 (68) & \(p\) = 0.18 \\  & Negative & 4 (8) & 6 (14) & \\  & Unknown & 4 (8) & 8 (18) & \\ \hline \end{tabular}
\end{table}
Table 1: Patient Characteristics by Treatment Site.  
Survival estimates were calculated based on the Kaplan-Meier product-limit method, and 95% confidence intervals were calculated using the \"exponential\" Greenwood variance (log-log transformation) estimate. Differences between Kaplan-Meier curves were assessed by the log-rank test. OS was measured from the date of diagnosis to death from any cause. Patients who were alive at the last contact date were censored. Progression-free survival (PFS) was measured from the date of diagnosis to disease progression or death, whichever occurred first. All calculations were performed using RStudio 1.2.5033; study data were locked for analysis on 15 January 2020.