© Wellcome Images Breast Cancer Cells Dividing - This confocal micrograph shows two human breast cancer cells dividing. The cell at the top is at prophase, showing the condensing chromosomes prior to their separation. The cell at the bottom is in anaphase, where the chromosomes are in the process of pulling apart.
Cancer patients may feel like they have alien creatures or parasites growing inside their bodies, robbing them of health and vigor. According to one cell biologist, that's exactly right. The formation of cancers is really the
evolution of a new parasitic species.Just as parasites do, cancer depends on its host for sustenance, which is why treatments that
choke off tumors can be so effective. Thanks to this parasite-host relationship, cancer can grow however it wants, wherever it wants. Cancerous cells do not depend on other cells for survival, and they develop chromosome patterns that are distinct from their human hosts, according to
Peter Duesberg, a molecular and cell biology professor at the University of California-Berkeley. As such, they're novel species.
He argues that the prevailing theories of carcinogenesis, or cancer formation, are wrong. Rather than springing from a few genetic mutations that spur cells to grow at an uncontrolled pace, cancerous tumors grow from a disruption of entire chromosomes, he says. Chromosomes contain many genes, so mis-copies, breaks and omissions lead to tens of thousands of genetic changes. The result is a cell with completely new traits: A new phenotype.