Fig. 1
From: The origins of breast cancer associated with mammographic density: a testable biological hypothesis
Two-stage model of carcinogenesis of Moolgavkar et al. [17]. In this model, normal stem cells, with a birth rate (α1) and rate of death (β1), can be transformed into cells of an intermediate form at a stochastic event rate (μ1) (the first mutation rate). These intermediate cells can divide into two further intermediate cells at a stochastic rate (α2), then die or differentiate at rate β2. In addition, intermediate cells can divide into one intermediate and one transformed (malignant) cell with a second stochastic event rate (μ2). The malignant cells are assumed to develop into a tumor after a deterministic lag time