Perspectives in mathematical biology Can mathematicians who prove theorems be useful to physicians who treat patients with cancer?Can mathematics have an impact on cancer biology? Is mathematics more than just a tool in the hands of [a few open-minded] physicians willing to understand and treat cancer from an innovative point of view? . . .and is mathematical biology more than just a toy in the hands of mathematicians? I imagine that most readers of this journal would join me in answering "yes" to these questions. But let me be more explicit in my questioning: Is there a place for a very abstract theoretical activity, as is proving theorems, in a team of physicians daily committed to treating human diseases (in particular cancer)? Can these physicians see the contribution of mathematicians to their difficult task as more than helping them to "think differently" (as some of them state it), but further as actually taking part in a therapeutic decision? As regards mathematical biology, when it is applied to medical questions, do we mathematicians feel enough committed to go beyond a fewpublications in the numerous journals dedicated to applications of maths to biology, and to collaborate with medical teams in a long term effort to improve in common medical treatments? Building on recent articles (Clairambault 2009, 2011) in which I have outlined technical ways by which one can achieve a working collaboration between mathematicians and physicians toward such mutual usefulness, I will explain briefly below why the answers to these questions should be "yes".