The early impact of the COVID-19 pandemic on access to colorectal cancer treatment in Brazil: a spatial and interrupted time-series analysis.

Background: The coronavirus disease 2019 (COVID-19) pandemic has caused unprecedented disruptions in cancer care globally, disproportionately affecting access in low- and middle-income countries. In Brazil, data on how specific treatment modalities and delays have evolved during the pandemic remain limited. This study aims to evaluate the impact of the COVID-19 pandemic on access to colorectal cancer (CRC) treatment in Brazil, focusing on regional disparities in the time from diagnosis to treatment initiation across therapeutic modalities. Methods: We conducted a nationwide, population-based study using data from the Oncology Panel of the Brazilian Unified Health System (SUS). Therapeutic modalities included surgery, chemotherapy, radiotherapy, and combined chemoradiotherapy, categorized by treatment initiation intervals: within 30 days, 31-60 days, and over 60 days. The age-standardized treatment access rate (ASTAR) were defined as the rate of patients initiating treatment within each interval. Spatial analyses were performed to examine regional disparities across Health Regions using ASTAR percentage change. For temporal evaluation, we applied an interrupted time-series (ITS) analysis using monthly ASTAR and the impact of the COVID-19 pandemic on the treatment access rate (ITAR), defining the pre-pandemic period as January 2018-March 2020 and the post-pandemic period as beginning in April 2020. ITAR was estimated by comparing observed and expected delay rates in 2020. Findings: A total of 118,720 CRC treatment records were analyzed, of which 50.44% were male and 49.56% female. The most pronounced disruptions occurred in the Health Regions in the North, Northeast, and Midwest. ITS analysis revealed a significant level decrease by April 2020 for early access to all the treatments combined (-0.035; 95% CI: -0.091 to -0.022), chemotherapy (-0.040; 95% CI: (-0.096 to 0.018) and surgery (-0.040; 95% CI: (-0.096 to 0.018), while radiotherapy (0.002; 95% CI: 0.000-0.004) showed no meaningful level change. In 2020, a marked decline in access to early treatment was observed: surgery, chemotherapy and chemoradiotherapy initiated within 30 days decreased by 18% compared with the expected levels (0.82; 95% CI: 0.68-0.96). Conversely, the rate of radiotherapy within 30 days increased by 43% (ITAR = 1.43; 95% CI: 1.27-1.58). Overall, access rates remained below pre-pandemic trends until 2022. Interpretation: The COVID-19 pandemic substantially disrupted access to colorectal cancer treatment in Brazil, particularly for timely surgical and chemotherapeutic interventions. Regional inequalities were exacerbated, disproportionately affecting underserved areas with historical structural limitations. Although partial recovery occurred with some modalities, treatment rates remained below expected levels through 2022. These findings highlight the vulnerability of oncology care pathways during public health crises and underscore the need for resilient, regionally coordinated strategies to protect timely cancer treatment in future emergencies. Funding: None.