The purpose of this study was to characterize the effects of institutional policies routine SARS-CoV-2 testing before treatment starts with mandatory quarantine periods for COVID-positive patients during the first year of the COVID19 pandemic across radiation oncology sections at our tertiary cancer center. Electronic medical databases were queried to identify all patients treated with curative intent at a large urban cancer center and regional satellites a year prior to the pandemic (02/11/19-12/30/19; pre-pandemic) and the first year of the pandemic (03/11/20-12/30/20; post-pandemic). New treatment starts were filtered for those undergoing treatment under a single ICD-10 diagnosis and the first treatment in each time period for each patient. Chi-square tests were used for categorical variables, and the t-test was used for continuous variables to correlate differences in demographic and clinical factors before and during the pandemic. The total number of new treatment starts were similar between the pre-pandemic (2,218 patients) and post-pandemic (2,130 patients) periods, but there was a 26% decrease in treatments in April 2020 compared to April 2019 and a 40% increase in treatments in November 2020 compared to November 2019. Post-pandemic patients had higher minimum Charlson Comorbidity Index scores (mean 46.0 vs 42.6, P = 0.0013) and were younger (62.8 yo vs 64.3 yo, P = 0.0001). The proportion of patients being treated from the same state as our institution was higher in the post-pandemic period compared to pre-pandemic (77.8% vs 72.43%, P = 0.0259). Distribution of treatments across department disease-site sections were significantly different (P<0.0001), with the proportion of patients treated by the Breast service having increased by 22% whereas the metropolitan area regional satellites experienced a 18% reduction. There were no statistically significant differences amongst pre- and post-pandemic patients with respect to race, marital status, or smoking status. Post-pandemic patients had less total radiation-related clinical visits (mean 24.8 vs 28.6, P<0.0001), lower administered dose (4329 cGy vs 4533 cGy, P<0.0001), and lower radiation fraction count (17 vs 19, P<0.0001). There was no statistically significant difference in the duration between CT simulation and treatment start, but post-pandemic patients had shorter duration of elapsed days during treatment (27 days vs 29 days, P = 0.0001). A disease-site-specific analysis demonstrated that these differences were most pronounced in patients treated for breast cancer. In the first year of the COVID19 pandemic, our institution saw a dynamic change in the number of new radiation treatments. Additional analyses across individual disease-specific services may reveal insight into dose, fractionation, and technique, which may account for the observed differences.