If cancer is 200 different diseases, why does it have one name?

This question lies at the heart of what cancer is, why some cancers are more deadly than others, why some respond better to treatment, and why two people with the same cancer and same stage of disease can respond differently to the same treatment. These questions are also at the core of controversies that arise when cancer activists lobby for one particular cancer and scientists object, saying that such action may divert funding from studies investigating questions relevant to all cancers.

The fact is, no one kind of cancer is like any other cancer; all cancers are different. Yet, all cancers are similar in terms of their fundamental underlying mechanisms.