The treatment of complex diseases like cancer may lie in grasping their mechanisms at all levels of biological hierarchy. Most research focuses on understanding how genes cause cancer from within a cell, but much can be learned from intercell interaction. In this regard, cancer cells are not only “antisocial”, but also exhibit a “gang culture”, whereby they act in concert to achieve certain pathological ends. In this “Cutting Edge” lecture, Janusz Rak, a Jack Cole Chair in Pediatric Hematology/Oncology and Pediatrics here at McGill University speaks about some of his research which focuses on these new ways to view cancer behaviour.