The Stem Cell Network model: clinical implications in cancer.

This review will discuss the aspects of stem cell biology that can contribute to explain tumor development and why standard oncology treatments sometimes fail. We also propose an integrated model of tumor progression based on the putative occurrence of Stem Cell Networks (SCNs). In a SCN, the somatic stem cells are derived from a common embryonic stem cell, share a specific molecular profile and maintain a high degree of cell-cycle synchronization. In the study of cancer, the SCN model introduces an additional conceptual frame to the interpretation of both the cancer stem cell (CSC) hypothesis and the field cancerization concept. The CSC model may explain how the cancer fields develop, justifies their sizes and shapes, contribute to explain the local recurrences in patients with free margins, the second primary tumors, the success of organ preserving surgical approaches or the trend of different tumors to metastasize to certain locations. We propose that the SCN model of cancer provides some clues for further understanding tumor progression and raises promising experimental and clinical implications.