Quantifying the duration of the preclinical detectable phase in cancer screening: a systematic review

Objectives: To provide an overview of published mathematical estimation approaches to quantify the duration of the preclinical detectable phase using data from cancer screening programs. Methods: A systematic search in PubMed and Embase for original studies presenting mathematical approaches using screening data. The studies were categorized by mathematical approach, data source and assumptions made. Furthermore, estimates of the duration of the preclinical detectable phase of breast and colorectal cancer were reported per study population. Results: From 689 publications, 34 estimation methods were included. Five distinct types of mathematical estimation approaches were identified: prevalence to incidence ratio (n=8), maximum likelihood estimation (n=16), expectation-maximization algorithm (n=1), regression of observed on expected (n=6) and Bayesian Markov Chain Monte Carlo estimation (n=5). Fourteen studies used data of a screened and an unscreened population whereas nineteen studies included only information from a screened population. Estimates of the duration of the preclinical detectable phase varied between two and seven years for breast cancer within the HIP study (annual mammography and clinical breast examination in women aged 40-64 years) and two and five years for colorectal cancer within the Calvados study (one guaiac fecal occult blood test in men and women aged 45-74 years). Conclusion: Different types of mathematical approaches lead to different estimates of the duration of preclinical detectable phase. We advise researchers to use the method that matches the data available, and use multiple methods for estimation when possible as no method is perfect