Colorectal cancer T stage, size at diagnosis, and presentation 2017 to 2023: an analysis using Veterans Affairs data.

[PURPOSE] Colorectal cancer is the fourth most common cancer in the United States, and early detection decreases mortality. We evaluated recent trends in colon cancer incidence and changes in rates of presentation with bowel obstruction before and during the COVID-19 pandemic.

[METHODS] This was a longitudinal study of United States veterans from 2017 to 2023. The primary exposure was the time period prepandemic (January 1, 2017, to February 29, 2020) compared with pandemic (March 1, 2020, to October 31, 2023). The primary outcome was new colon cancer diagnoses. We compared observed with expected diagnoses during the pandemic period. Malignant bowel obstruction at the index diagnosis date, American Joint Committee on Cancer tumor stage, and tumor size at the time of diagnosis were compared by period using standardized differences and bootstrapped CIs.

[RESULTS] There were 22,256 new colon cancer diagnoses made in United States Department of Veterans Affairs Medical Centers (VA): mean age of 71 ± 11 years, 96% male, and 72% White. Comparing the pandemic with prepandemic periods, the proportion of cancers >4 cm increased from 48.9% to 57.3% and the proportion with malignant bowel obstruction at presentation doubled from 2.7% to 5.3%. An estimated 619 cases were "missed" during the pandemic: they were expected but not observed diagnoses. There were greater observed than expected large cancers and fewer observed than expected small cancers during the pandemic according to forecast analyses.

[CONCLUSION] Interruptions in care after the onset of the COVID-19 pandemic had measurable consequences among United States veterans through the end of 2023. Among those diagnosed, the median size was larger and more presented with bowel obstruction. This may be because decreased screening activity combined with lower healthcare utilization changed the distribution of cancer size at diagnosis to be larger, underlining the importance of encouraging engagement or re-engagement of veterans in colorectal cancer screening.