To compare ISIS to cancer is to libel cancer. A single cancer never causes mass death.
War with ISIS is inevitable. It is impossible to cut deals with people for whom genocide is policy and for whom war crimes are military policy. Maliki of course must go, as he has created much of the problem.
The greatest evil is not now done in those sordid "dens of crime" (or) even in concentration camps and labour camps. In those we see its final result. But it is conceived and ordered... in clean, carpeted, warmed and well-lighted offices, by (those) who do not need to raise their voices. Hence, naturally enough, my symbol for Hell is something like the bureaucracy of a police state or the office of a thoroughly nasty business concern."
― C.S. Lewis, The Screwtape Letters