I think the reference is meant to invoke the image of incontrollable growth of cells that spreads to other parts of the body and eventually consumes the body and kills the host. Because capitalist growth is driven by profit expectations, I think the executive leadership of many companies feel market pressure to continuously grow profits and to do so rapidly. They become a "mind cancer" when they grow profits irresponsibly by encouraging hyper consumption, shifting environmental and other costs onto others.

Rapid growth leads to market saturation (unless population growth outpaces it), the collapse or consolidation of producers and a concentration of capital.

Economic inequality is justified on the grounds that the wealthy are more virtuous than the poor.