The 2019 coronavirus disease (COVID-19) pandemic has impacted cancer care and the diagnosis of new cases of cancer. We analyzed the impact of the COVID-19 pandemic on patients with cancer by comparing the number of newly diagnosed cases, cancer stage, and time to treatment in 2020 with those in 2018, 2019, and 2021. A retrospective cohort of all cancer cases treated at A.C. Camargo Cancer Center in 2018–2021, identified from the Hospital Cancer Registry, was studied. We analyzed single and multiple primary cancer case and patient characteristics—by year and by clinical stage (early v advanced). Times from diagnosis to treatment were compared according to the most frequent tumor sites between 2020 and the other study years. Between 2018 and 2021, a total of 29,796 new cases were treated at the center including 24,891 with a single tumor and 4,905 with multiple tumors, including nonmelanoma skin cancer. The number of new cases decreased by 25% between 2018 and 2020 and 22% between 2019 and 2020, followed by an increase of about 22% in 2021. Clinical stages differed across years, with the number of new advanced cases decreasing from 17.8% in 2018 to 15.2% in 2020. Diagnoses of advanced-stage for lung and kidney cancer decreased between 2018 and 2020, while the number of thyroid and prostate cancer cases diagnosed in advanced-stages increased from 2019 to 2020. The time from diagnosis to treatment decreased between 2018 and 2020 for breast (55.5 v 48 days), prostate (87 v 64 days), cervical/uterine (78 v 55 days) and oropharyngeal (50 v 28 days) cancers. The COVID-19 pandemic affected the numbers of single and multiple cancers diagnosed in 2020. An increase in the number of advanced-stage cases diagnosed was observed only for thyroid and prostate cancer. This pattern may change in coming years due to the possibility that a significant number of cases went undiagnosed in 2020.
