Changes in the number of cancer diagnosis practices due to the COVID-19 pandemic: interrupted time-series analysis using the National Database of Japan.

purposeThis study aimed to reveal the impact of coronavirus disease 2019 on the number of practices commonly used for cancer diagnosis in Japan.

methodsThe sampling dataset of the National Database of Japan from January 2015 to January 2021 was used to generate 25-point time-series data for the number of practices (21 points before and 4 points during the pandemic outbreak). The decreased number was estimated by interrupted time-series analysis using a seasonal autoregressive integrated moving average model. Using the pre-pandemic data, expected counterfactual numbers during the pandemic were predicted, and decreased rate was calculated.

resultsIn most practices, the number dramatically decreased in the early stage of the pandemic and recovered rapidly thereafter. As of April 2020, gastric endoscopy decreased at the top of the practices (- 42.1%, with 95% confidence intervals of - 50.5% and - 33.7%), followed by gastric biopsy (- 38.6%, with 95% confidence intervals of - 46.7% and - 30.6%). The period of declined practices for lung cancer was relatively prolonged. The number of sentinel lymph node biopsies for breast cancer and colposcopies and biopsies for cervical cancer did not decrease in April 2020, but significantly decreased later in July 2020, which is assumed to be the time lapse after the primary testing before surgical treatment or intense scrutiny.

conclusionIn general, the number of practices for cancer diagnosis in Japan showed only a temporary decline, which was concordant with reports from several other countries.