The dominance of the microenvironment in breast and ovarian cancer.

That cancer development is a multistep process, driven in large part by genetic change, is well established. However, it is becoming increasingly clear that, prior to its emergence, the tumorigenic phenotype must overcome the suppressive effects of the surrounding microenvironment. Because the microenvironment is tissue-specific, cancer in each organ must develop unique strategies to overcome these normal epigenetic suppressors. Surprisingly, the induction of glandularity during the earliest stages of ovarian carcinoma development produces a microenvironment that has much in common with the normal mammary gland. This phenotypic convergence may explain why similar genetic and epigenetic changes appear to play a role in breast and ovarian tumor progression. Copyright 2002 Published by Elsevier Science Ltd.