Seminar in PSA 106 at 3:40p.m.

ABSTRACT:

A malignant tumor is a dynamic amalgamation of various cell phenotypes, both
cancerous (parenchyma) and healthy (stroma). These diverse cells compete over
resources as well as cooperate to maintain tumor viability. Therefore, tumors
are both an ecological community and an integrated tissue. An understanding of
how natural selection operates in this unique ecological context should expose
unappreciated vulnerabilities shared by all cancers. In this study I address
natural selection's role in tumor evolution by developing and exploring a
mathematical model of a heterogeneous primary neoplasm. The model is a system of
nonlinear ordinary differential equations tracking mass of up to 2 different
parenchyma cell types, mass of vascular endothelial cells from which new tumor
blood vessels are built and total length of tumor microvessels. Results predict
the possibility of a hyper umor -- a focus of aggressively reproducing
parenchyma cells that invade and destroy all or part of the tumor, perhaps
before it becomes a clinical entity. If this phenomenon occurs, then we should
see examples of tumors that develop an aggressive histology but are
paradoxically prone to extinction. Neuroblastoma, a common childhood cancer,
may sometimes fit this pattern. In addition, this model suggests that
parenchyma cell diversity can be maintained by a tissue-like integration of
cells specialized to provide different services.