In incurable diseases, maintenance therapy aims to prolong the response achieved through induction. The goal is to delay disease progression, thus prolonging survival. Two maintenance modalities are used. The first, called continuation maintenance, consists of continuing the same agent used in the initial treatment. The second, called switch-maintenance, introduces an early second line drug immediately after induction. Proving the superiority of a maintenance strategy implies a better outcome with the maintenance compared to the same therapeutic agent used upon disease progression. This benefit may be observed in terms of overall survival and/or quality of life.