There are lots of things that every cancer must do. Read one of Bob Weinberg&#x27;s &quot;hallmarks of cancer&quot; papers for an overview. Telomeres are just one thing. They must also activate growth signalling, evade the immune system, promote vascularization, repress tumor suppression mechanisms or otherwise avoid apoptosis or senescence, etc. All of these are valid targets for therapy, and most of them have been tried.