AbstractBackgroundWith access to cancer care services limited because of coronavirus disease 2019 control measures, cancer diagnosis and treatment have been delayed. The authors explored changes in the counts of US incident cases by cancer type, age, sex, race, and disease stage in 2020.MethodsData were extracted from selected US population‐based cancer registries for diagnosis years 2015–2020 using first‐submission data from the North American Association of Central Cancer Registries. After a quality assessment, the monthly numbers of newly diagnosed cancer cases were extracted for six cancer types: colorectal, female breast, lung, pancreas, prostate, and thyroid. The observed numbers of incident cancer cases in 2020 were compared with the estimated numbers by calculating observed‐to‐expected (O/E) ratios. The expected numbers of incident cases were extrapolated using Joinpoint trend models.ResultsThe authors report an O/E ratio <1.0 for major screening‐eligible cancer sites, indicating fewer newly diagnosed cases than expected in 2020. The O/E ratios were lowest in April 2020. For every cancer site except pancreas, Asians/Pacific Islanders had the lowest O/E ratio of any race group. O/E ratios were lower for cases diagnosed at localized stages than for cases diagnosed at advanced stages.ConclusionsThe current analysis provides strong evidence for declines in cancer diagnoses, relative to the expected numbers, between March and May of 2020. The declines correlate with reductions in pathology reports and are greater for cases diagnosed at in situ and localized stage, triggering concerns about potential poor cancer outcomes in the coming years, especially in Asians/Pacific Islanders.Plain Language Summary To help control the spread of coronavirus disease 2019 (COVID‐19), health care organizations suspended nonessential medical procedures, including preventive cancer screening, during early 2020. Many individuals canceled or postponed cancer screening, potentially delaying cancer diagnosis. This study examines the impact of the COVID‐19 pandemic on the number of newly diagnosed cancer cases in 2020 using first‐submission, population‐based cancer registry database. The monthly numbers of newly diagnosed cancer cases in 2020 were compared with the expected numbers based on past trends for six cancer sites. April 2020 had the sharpest decrease in cases compared with previous years, most likely because of the COVID‐19 pandemic.