Changes in oncological surgical volume and postoperative survival during the COVID-19 pandemic: a retrospective multicenter study in a regional German hospital network.

Purpose: The COVID-19 pandemic led to delays in elective procedures and a reduction in oncological resections worldwide, potentially affecting the prognosis of cancer patients. This study assessed changes in surgical volume, tumor stage distribution, and postoperative overall survival across the pre-pandemic, pandemic, and post-pandemic periods within a regional network comprising one tertiary referral center and two peripheral hospitals. Methods: This retrospective multicenter observational study included oncological surgical procedures performed in three surgical departments in Halle (Saale) between August 1, 2017, and April 30, 2025. The data were stratified into pre-pandemic, pandemic, and post-pandemic periods. Study outcomes included surgical volume, tumor stage distribution, and postoperative overall survival. Survival analyses were performed in a patient-based cohort using the first eligible procedure as the index operation and assessed at predefined postoperative time points. Results: A total of 2871 oncological surgical procedures were analyzed across pre-pandemic (n=952), pandemic (n=940), and post-pandemic (n=979) periods. Monthly surgical volume fluctuated across the observation period, reaching its lowest value in April 2020 and December 2021 (n = 20) and its highest value in January 2021 (n = 40). Among patients included in the survival analysis, the proportion of UICC stage IV was higher during the pandemic (26.8%) than in the pre-pandemic (23.9%) or post-pandemic (24.2%) periods. Kaplan-Meier analysis showed a trend toward shorter postoperative overall survival during the pandemic period (log-rank p = 0.066). In multivariable Cox regression adjusted for age, sex, tumor stage, and resection site, the pre-pandemic cohort was associated with a lower hazard of death than the pandemic cohort (HR 0.78, 95% CI 0.65-0.93; p = 0.005). Conclusion: Changes in oncological surgical volume were observed across the study periods. During the pandemic period, a higher proportion of advanced tumor stages at presentation and a trend toward shorter postoperative overall survival were observed. After adjustment for baseline characteristics, the pre-pandemic cohort showed a lower mortality hazard than the pandemic cohort. These findings support the importance of resilient healthcare infrastructures for continuous, guideline-concordant oncological care.