Model-Based Evaluation of Spontaneous Tumor Regression in Pilocytic Astrocytoma
Fig 3
Tumor regression in the TGP model.
A. Partial resection of a PA-I tumor reduces the number of tumor cells to size k which is assumed to be below the critical tumor size N. The residual tumor can regrow, progress or regress based on the same dynamics that led to the primary tumor. Hence, the TGP dynamics with relevant cell number N is utilized to describe the further development of the residual tumor. Regression is achieved if state 0 is reached, i.e. no tumor cells are present anymore. B. The red area indicates the resected part of the diagnosed PA-I tumor. This resection leads to removal of both tumor and wild-type cells. Subsequently, the residual number of tumor cells k competes with other wild-type cells which can lead to regrowth, regression or progression of the residual tumor. We assume that N is the relevant cell number for this competition as in the formation of the primary tumor. This relevant cell number is indicated by the blue circle.