Basic Equations and Computing Procedures for Frailty Modeling of Carcinogenesis: Application to Pancreatic Cancer Data. (January 2013)

• Record Type: Journal Article
• Authors: Mdzinarishvili, Tengiz; Sherman, Simon
• Is Part Of: Cancer informatics. Volume 12(2013)
• Publication Date: 2013-01
• Subjects: cancer incidence -- cancer hazard -- frailty -- Weibull distribution -- pancreatic cancer; Bioinformatics -- Periodicals; Biology -- Data processing -- Periodicals; Cancer -- Periodicals; Cancer -- Research -- Periodicals; Computational biology -- Periodicals; 570.285
• DOI: 10.4137/CIN.S8063
• Languages: English
• ISSNs: 1176-9351

Abstract

Modeling of cancer hazards at age t deals with a dichotomous population, a small part of which (the fraction at risk) will get cancer, while the other part will not. Therefore, we conditioned the hazard function, h ( t ), the probability density function (pdf), f ( t ), and the survival function, S ( t ), on frailty α in individuals. Assuming α has the Bernoulli distribution, we obtained equations relating the unconditional (population level) hazard function, hU ( t ), cumulative hazard function, HU ( t ), and overall cumulative hazard, H 0, with the h ( t ), f ( t ), and S ( t ) for individuals from the fraction at risk. Computing procedures for estimating h ( t ), f ( t ), and S ( t ) were developed and used to ft the pancreatic cancer data collected by SEER9 registries from 1975 through 2004 with the Weibull pdf suggested by the Armitage-Doll model. The parameters of the obtained excellent fit suggest that age of pancreatic cancer presentation has a time shift about 17 years and five mutations are needed for pancreatic cells to become malignant.