[AstralStorm]

This is true for most stationary cancers before they turn malignant.

Immune cells are already resistant to each other, and especially to stress. Additionally, they have pieces of genetic code that are manipulated during their life and potential to become self-reactive with no activation. If they lose anergy and apoptosis, it can be enough, and there are many paths to activate them into mitosis.

Immune cells can become a cancer just by their number and statistics of error. Just big leukemia is but a symptom but has potential for first stage cancer.