Cancer is genetically like another species!
When we present the diversity and genetic variability of cancer, our readers often ask if cancer cells are still human cells. This is not a bad question. The karyotype (the number and type of chromosomes in a cancer cell) sometimes looks more like that of wheat or a newt than a human!
There are 23 pairs of chromosomes in a normal cell of the human body, in which the arrangement and order of genes are strictly defined. In cancer cells, however, we can find less than 40 or more than 100 (!) chromosomes, and many of them do not have the typical banding characteristic of Homo sapiens.
In genomes of tumors, gene recombination, insertions, deletions or multiplication of some parts, or whole sets, of chromosomes may occur. Sometimes it happens that the tumour’s karyotype does not resemble the human’s whatsover, which is when genomists who want to analyze it must resort to the tools used in phylogenetics to compare evolutionary distant species.
Since cancer also evolves within us to avoid the body’s various defense mechanisms, like a parasite in our bodies.