Impact of COVID-19 on gynecological cancer incidence: a large cohort study in Japan

Background The influence of the coronavirus disease 2019 (COVID-19) pandemic on the number of newly diagnosed gynecological cancers has not been extensively investigated in Japan. This study determined the impact of COVID-19 on the incidence of gynecological cancer. Methods Using the Japanese Society of Obstetricians and Gynecologic Oncology registry database, the distribution of the number of patients based on clinical staging or tumor-node-metastasis classifications before and during the COVID-19 pandemic was analyzed to compare the trends. The clinical staging classification of cervical cancer in Japan was based on the International Federation of Gynecology and Obstetrics (FIGO) 2008 from 2018 to 2020 and on the FIGO 2018 from 2021. Since FIGO-2018 classified N1 cases as stage IIIC, we focused on T classification without referencing the clinical staging (FIGO staging) of patients with cervical cancer in 2021. Results The number of patients with endometrial cancer and malignant ovarian tumors of all clinical stages increased uniformly yearly, while that of those with stage III cervical cancer rapidly increased in 2021 owing to the adoption of the revised classification. On comparing cases of cervical cancer in 2020 and 2021, we found that T1 cases decreased and T2 and T3 cases increased in 2021 compared to those in 2020 (p = 0.006). Cervical intraepithelial neoplasia/adenocarcinoma in situ incidence decreased in 2020 compared to that in 2019 but increased again in 2021. The number of patients with cervical cancer decreased in most prefectures in 2020. Conclusion The incidence of locally advanced cervical cancer increased during the COVID-19 pandemic.