Cancer incidence during the COVID-19 pandemic by region of residence in Manitoba, Canada: A cancer registry-based interrupted time series study.

INTRODUCTION

Health care in Manitoba, Canada is divided into five regions, each with unique geographies, demographics, health care access, and health status. COVID-19-related restrictions and subsequent responses also differed by region. To understand the impact of the pandemic on cancer incidence in the context of these differences, we examined age-standardized cancer incidence rates by region over time before and after the COVID-19 pandemic.

METHODS

We used a population-based quasi-experimental study design, population-based data, and an interrupted time series analysis to examine the rate of new cancer diagnoses before (January 2015 until December 2019) and after the start of COVID-19 and the interventions implemented to mitigate its impact (April 2020 until December 2021) by region.

RESULTS

Overall cancer incidence differed by region and remained lower than expected in Winnipeg (4.6% deficit, 447 cases), Prairie Mountain (6.9% deficit, 125 cases), and Southern (13.0% deficit, 238 cases). Southern was the only region that had a significantly higher deficit in cases compared to Manitoba (ratio 0.92, 95% CI 0.86, 0.99). Breast and colorectal cancer incidence decreased at the start of the pandemic in all regions except Northern. Lung cancer incidence decreased in the Interlake-Eastern region and increased in the Northern region. Prostate cancer incidence increased in Interlake-Eastern.

CONCLUSIONS

The impact of the COVID-19 pandemic on cancer incidence differed by region. The deficit in the number of cases was largest in the southern region and was highest for breast and prostate cancers. Cancer incidence did not significantly decrease in the most northern, remote region.