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Comparison of α/β estimates from homogeneous (individual) and heterogeneous (population) tumor control models for early stage prostate cancer
Author(s) -
Carlone Marco,
Wilkins David,
Nyiri Balazs,
Raaphorst Peter
Publication year - 2003
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.1612946
Subject(s) - statistics , confidence interval , mathematics , poisson distribution , population , homogeneous , poisson regression , linear model , medicine , combinatorics , environmental health
Radiobiological parameter estimates for prostate cancer are obtained from both a homogeneous (individual) and heterogeneous (population) tumor control model based on Poisson statistics and the linear quadratic model of cell survival. Parameter estimates for both models are highly correlated: statistically equivalent fits are achievable using either (1) linear quadratic (LQ) parameters with low numbers of radioresistant tumor stem cells, or (2) LQ parameters with corresponding larger number of radiosensitive tumor stem cells. A theoretical framework is developed to explain this correlation. A Monte Carlo error analysis based on binomial statistics is used to estimate confidence intervals for all parameter estimates. It was found that both the homogeneous and heterogeneous models produce approximately equivalent estimates of radiobiological parameters, including the α/β ratio. However, the 95% confidence interval for the α/β ratio derived from the heterogeneous model are considerably larger than those derived from the homogeneous model, which indicate the homogeneous model overestimates the statistical significance of the α/β estimate.