A stochastic model for survival of early prostate cancer with adjustments for leadtime, length bias, and over-detection.
To compare the survival between screen-detected and clinically detected cancers, we applied a series of non-homogeneous stochastic processes to deal with leadtime, length bias, and over-detection by using full information on detection modes obtained from the Finnish randomized controlled trial for prostate cancer screening. The results show after 9-year follow-up the hazard ratio of prostate cancer death for screen-detected cases against clinically detected cases increased from 0.24 (95% CI: 0.16-0.35) without correction for these biases, to 0.76 after correction for leadtime and length biases, and finally to 1.03 (95% CI: 0.79-1.33) for a further adjustment for over-detection. Adjustment for leadtime and length bias but no over-detection led to a 24% reduction in prostate cancer death as a result of prostate-specific antigen test. The further calibration of over-detection indicates no gain in survival of screen-detected prostate cancers (excluding over-detected case as stayer considered in the mover-stayer model) as compared with the control group in the absence of screening that is considered as the mover. However, whether the model assumption on over-detection is robust should be validated with other data sets and longer follow-up.
Tampere School of Public Health, University of Tampere, Tampere, Finland.
Grace Hui-Min
GH
Wu
Anssi
A
Auvinen
Amy Ming-Fang
AM
Yen
Matti
M
Hakama
Stephen D
SD
Walter
Hsiu-Hsi
HH
Chen
D015982:Bias; D002986:Clinical Trials as Topic; D018450:Disease Progression; D005189:False Positive Reactions; D006801:Humans; D008297:Male; D008390:Markov Chains; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000453:epidemiology* / Q000401:mortality; D015996:Survival Rate