A New Integrative Modeling Approach for Generating Counterfactual Projections of Colorectal Cancer Incidence Rates in...

Area of Science:

• Epidemiology
• Public Health
• Biostatistics

Background:

• The Australian National Bowel Cancer Screening Program (NBCSP) was implemented in phases from 2006 to 2020.
• The program offers 2-yearly screening for colorectal cancer (CRC) to individuals aged 50 to 74.

Purpose of the Study:

• To develop an integrative modeling approach to project CRC incidence rates from 2006 to 2045 in the absence of the NBCSP.
• To establish a counterfactual benchmark for evaluating the NBCSP's effectiveness.
• To address complex age-specific trends in CRC incidence.

Main Methods:

• Constructed a new dataset by replacing observed data for NBCSP-eligible individuals with intermediate projections.
• Compared standard age-period-cohort (APC) models, age-stratified APC models, and the novel integrative modeling approach.
• Generated "no-NBCSP projections" for CRC incidence.

Main Results:

• The integrative modeling approach demonstrated superior performance in capturing complex age-specific CRC incidence trends compared to standard APC models.
• Without the NBCSP, overall CRC incidence was projected to decline until 2025, then increase from 2026 to 2045.
• Projected increases in CRC incidence were observed for individuals under 50, and for older age groups starting from 2020 onwards, with later increases for progressively older cohorts.

Conclusions:

• The "no-NBCSP projections" serve as a crucial counterfactual benchmark for assessing the NBCSP's impact on CRC incidence in Australia.
• The developed methods can be adapted to evaluate other public health interventions.
• Findings highlight the need for continuous evaluation of the NBCSP's starting age to address rising incidence in younger populations.