Time trend and geographical distribution of colorectal cancer incidence before and after COVID-19 pandemic in southern Iran: an interrupted time series analysis.

AIM: This study aimed to assess the trend and geographical distribution of colorectal cancer (CRC) in Fars province from 2011 to 2024, and its changes during COVID-19.

BACKGROUND

Research has indicated that the risk of CRC varies significantly across different regions of the world.

METHODS

From 2011 to 2024, data from 1,453 CRC patients who were registered in the Shiraz Colorectal Cancer Surgery (SCORCS) program were analyzed. Using R software (v4.2.0), we applied interrupted time series analysis to evaluate the impact of COVID-19 on CRC incidence and mortality. Spatial distribution was examined with ArcGIS (v10.4.1), and Moran's I test was used to determine high- and low-risk regions. A 5% significance level was applied to all analyses.

RESULTS

In this study, 56.2% of the patients were men and 43.8% were women. Most patients (49%) were between 30 and 59 years old. Rectal cancer was slightly more common (57.7%) than colon cancer (41.8%), and only a very small number (less than 0.5%) had both. About half of the patients were classified as T3, and over 80% already had metastasis. At the pandemic onset, both outcomes showed a significant immediate increase, followed by a significant post-pandemic decline in slope. Among the studied areas, Kazerun and Jahrom had the highest incidence rate, while Zarqan and Kazerun showed the highest mortality rate.

CONCLUSION

This study shows that CRC incidence and mortality declined during COVID-19, likely due to restrictive policies. However, the high rates in some cities of Fars province highlight the need for targeted interventions to reduce the disease burden.