# Estimating the impact of missed colorectal cancer diagnoses on life expectancy in Minamisoma City following the 2011 triple disaster

## TL;DR

This study estimates how missed colorectal cancer screenings after a disaster in Japan affected life expectancy, showing the importance of maintaining health services during crises.

## Contribution

A novel quantitative model to estimate life expectancy loss due to disrupted cancer screening after a disaster.

## Key findings

- Estimated 1.794 missed CRC cases in men and 1.203 in women due to decreased screening.
- Modeled additional life expectancy loss of 0.428 person-years for men and 0.229 for women.
- Cost per life-year saved was higher for women compared to men.

## Abstract

After the 2011 Great East Japan Earthquake, participation in colorectal cancer (CRC) screening significantly decreased in Minamisoma City, Fukushima Prefecture. However, the long-term health effects of this decline in screening participation have not been quantified. This study aims to construct a model to evaluate the impact of post-disaster decreases in CRC screening participation on population health.

We utilized the population and CRC screening data targeting 40–74 years-old residents in Minamisoma City. We compared the actual screening participation in 2011 with projected participation rates based on pre-disaster levels to estimate the number of residents who missed screening due to the disaster. Based on national CRC screening performance data and stage-specific survival rates in Japan, we estimated the number of missed CRC cases and modeled the additional the loss of life expectancy (LLE) due to CRC resulting from a one-year delay in diagnosis.

The estimated number of colorectal cancer cases that might have been missed due to decreased screening participation was 1.794 (95% uncertainty interval: 1.597 to 1.994) for men and 1.203 (0.931 to 1.491) for women. The missed detection opportunities estimated result in 0.428 (0.282 to 0.582) person-years [2.684 (1.793 to 3.604) years per 10,000 persons] and 0.229 (0.103 to 0.372) person-years [0.993 (0.450 to 1.608) years per 10,000 persons] of additional LLE for men and women, respectively. The estimated cost per life-year saved was 1.12×106 (0.81×106  to 1.62×106 yen for men and 3.65×106  (2.02×106  to 7.19×106 ) yen for women, respectively.

The calculated additional LLE due to missed CRC screening was relatively small but suggests preventive health services should be considered in disaster response planning. These findings provide a quantitative framework for evaluating health impacts of service disruptions.