The COVID-19 pandemic has reduced the capacity to diagnose and treat cancer worldwide due to the prioritization of COVID-19 treatment. The aim of this study was to investigate treatment and outcomes of colon cancer in Sweden before and during the COVID-19 pandemic.In an observational study, using the Swedish Colorectal Cancer Registry, we included (i) all Swedish patients diagnosed with colon cancer, and (ii) all patients undergoing surgery for colon cancer, in 2016-2020. Incidence of colon cancer, treatments and outcomes in 2020 were compared with 2019.The number of colon cancer cases in Sweden in April-May 2020 was 27% lower than the previous year, whereas no difference was observed on an annual level (4,589 vs. 4,763 patients [-4%]). Among patients with colon cancer undergoing surgery in 2020, the proportion of resections was 93 vs. 94% in 2019, with no increase in acute resections. Time from diagnosis to elective surgery decreased (29 days vs. 33 days in 2020 vs. 2019). In 2020, more patients underwent a two-stage procedure with a diverting stoma as first surgery (6.1%) vs. (4.4%) in 2019 (p = 0.0020) and more patients were treated with preoperative chemotherapy (5.1%) vs. (3,5%) 2019 (p = 0.0016). The proportion of patients that underwent laparoscopic surgery increased from 54% to 58% (p = 0.0017) There were no differences in length of stay, surgical complications, reoperation, ICU-stay or 30-day mortality between the years.Based on nationwide annual data, we did not observe adverse effects of the COVID-19 pandemic on colon cancer treatment and short time outcomes in Sweden.