Behavioral activation therapy (BAT) is a brief, manualized therapy that has shown efficacy in the treatment of major depressive disorder (MDD) and generalized anxiety disorder (GAD) in several controlled trials patients, including adult cancer patients. The goal of this open label clinical trial is to obtain preliminary evidence of the efficacy of BAT(6 sessions) in a group of adolescent cancer patients with MDD, GAD or adjustment disorder with mood or anxiety features.