Background: Effective cancer screening leads to a substantial increase in the detection of earlier stages of cancer, while decreasing the incidence of later stage cancer diagnoses. Timely screening programs are critical in reducing cancer-related mortality in both breast and colorectal cancer by detecting tumors at an early, curable stage. The COVID-19 pandemic resulted in the postponement or cancellation of many screening procedures, due to both patient fears of exposures within the healthcare system as well as the cancellation of some elective procedures. We sought to identify how the COVID-19 pandemic has impacted the incidence of early and late stage breast and colorectal cancer diagnoses at our institution. Methods: We examined staging for all patients presenting to UCSD at first presentation for a new diagnosis of malignancy or second opinion in 2019 and 2020. Treating clinicians determined the stage at presentation for all patients using an AJCC staging module (8^th edition) in the electronic medical record (Epic). We compared stage distribution at presentation in 2019 vs 2020, both for cancers overall and for colorectal and breast cancer, because these cancers are frequently detected by screening. Results: Total numbers of new patient visits for malignancy were similar in 2019 and 2020 (1894 vs 1915 pts), and stage distribution for all cancer patients was similar (stage I 32% in 2019 vs 29% in 2020; stage IV 26% in both 2019 and 2020). For patients with breast cancer, we saw a lower number of patients presenting with stage I disease (64% in 2019 vs 51% in 2020) and a higher number presenting with stage IV (2% vs 6%). Similar findings were seen in colorectal cancer (stage I: 22% vs 16%; stage IV: 6% vs 18%). Conclusions: Since the COVID-19 pandemic, there has been an increase in incidence of late stage presentation of colorectal and breast cancer, corresponding with a decrease in early stage presentation of these cancers at our institution. Cancer screening is integral to cancer prevention and control, specifically in colorectal and breast cancers which are often detected by screening, and the disruption of screening services has had a significant impact on our patients. We plan to continue following these numbers closely, and will present data from the first half of 2021 as it becomes available.