Recent cancer research has opened a window into a new world of biology: intelligent cancers.
Oncologists have known for decades that men with metastatic (e.g., spread to bones) prostate cancer will show clinical improvement if the level of testosterone in their blood is lowered. The tumor cells require male hormones (testosterone, made in the testis, or less powerful androgens made in the adrenal glands) to grow. Lowering testosterone used to be accomplished by removing the testicles; more recently it has been achieved by drugs.
Unfortunately the benefit of this intervention lasts only a year or two, after which prostate cancer starts to grow again throughout the body. The reason for this phenomenon was thought to be that the tumor cells remaining after initial hormone manipulation lacked the ability to respond to hormone withdrawal because they had undergone a genetic mutation and had lost a receptor on their surface which recognizes male hormones. This concept is in keeping with conventional wisdom in oncology that acquired drug resistance is a function of spontaneous mutation which occurs randomly over time. New research has forced the cancer research community to question this paradigm.