Impact of the COVID-19 pandemic on the diagnosis, tumor characteristics, and survival outcomes of colorectal cancer: a retrospective cohort study.

Background: The coronavirus disease (COVID-19) pandemic has significantly disrupted healthcare systems, delaying the diagnosis and treatment of various diseases, including colorectal cancer (CRC).

Objectives: To determine differences in patient demographics, clinical and histopathological characteristics, and survival rates in patients diagnosed with CRC before and during the first year of the pandemic.

Design: Retrospective cohort study.

Setting: Tertiary-care center.

Patients and methods: We included 284 patients newly diagnosed with CRC, stratified into two cohorts: those diagnosed one year before and during the first year of the pandemic. Patient demographics, tumor characteristics (diameter, location, histological type, grade, multifocality, invasion depth, lymphovascular and perineural invasion, number of metastatic lymph nodes, tumor budding, and deposits), and clinical factors (operability, presence of distant metastases, and survival status) were evaluated.

Main outcome measures: Tumor stage at diagnosis, histopathological aggressiveness, and overall survival rates.

Sample size: 284 patients.

Results: Patients diagnosed during the pandemic had a significantly higher incidence of distant metastasis (14.8% vs. 5.1%, P=.005), a greater proportion of pT4b stage tumors (12.9% vs. 0.6%, P<.001), and a higher prevalence of rectosigmoid tumors (41.4% vs. 24.4%, P=.002). Additionally, tumor budding (63.6% vs. 47.3%, P=.014) and perineural invasion (35.2% vs. 24.5%, P=.053) were more common in the pandemic cohort. During the pandemic, significant shifts occurred in treatment modalities (P=.005), with increased utilization of neoadjuvant chemotherapy (18.8% vs. 11.5%), radiotherapy (22.7% vs. 12.2%), and palliative treatments (14.9% vs. 5.1%). Survival analysis showed no differences in survival rates between groups across all time points, including at three-year follow-up (P>.05).

Conclusions: The COVID-19 pandemic has led to increased metastasis and advanced tumor rates in CRC cases, possibly owing to diagnostic delays. Although survival outcomes were similar between the periods, delayed effects on prognosis may manifest, necessitating long-term follow-up.

Limitations: Retrospective design, single-center study.