Purpose
This study aimed to reveal the impact of coronavirus disease 2019 on the number of practices commonly used for cancer diagnosis in Japan.
Methods
The 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.
Results
In 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.
Conclusion
In general, the number of practices for cancer diagnosis in Japan showed only a temporary decline, which was concordant with reports from several other countries.
Supplementary Information
The online version contains supplementary material available at 10.1007/s00432-022-04557-2.
Various countries have reported a decrease in breast cancer surgeries during the coronavirus disease 2019 (COVID-19) pandemic; however, inconsistent results have been reported in Japan. This study revealed changes in the number of surgeries during the pandemic using the National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB) from January 2015 to January 2021, where insurance claims data from Japan as a whole are comprehensively accumulated. The number of breast-conserving surgeries (BCS) without axillary lymph node dissection (ALND) significantly decreased in July (− 846; 95% confidence interval (CI) − 1190 to − 502) and October 2020 (− 540; 95% CI − 861 to − 218). No decrease was observed for other types of surgery, BCS with ALND, and mastectomy with or without ALND. In the age-specific subgroup analysis, significant and transient reduction in BCS without ALND was observed in all age groups (0–49, 50–69, and ≥ 70 years). The number of BCS without ALND significantly decreased for a relatively short period in the early pandemic stages, suggesting reduced surgery for patients with a relatively low stage of cancer. Some patients with breast cancer might have been left untreated during the pandemic, and an unfavorable prognosis would be a concern.
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