This article discusses the origin and implications of the “war on cancer” metaphor. Commonly present in mass media, the “war on cancer” notion circulates also among patients, their loved ones, their support networks, and oncological multidisciplinary teams. In our view when cancer is uprooted of its illness status, and conceptualized as an “enemy”, myths about disease and those who suffer it (especially the idea of psychogenesis) are strengthened. Two topics in which the war metaphor is particularly problematic in the clinical context, are analyzed in depth. The first one is the relationship between the oncologic patient with his loved ones and support networks. When patients are insistently prompted to fight the disease and think positive, the expression of emotions associated to the adaptive process of receiving a diagnosis of cancer are inhibited. Secondly, the war metaphor promotes an authoritarian view among the health teams and on the doctor-patient relationship, undermining the patent's autonomy in the decision-making process, which may affect his global quality of life. Also, it encourages emotional isolation, concealment of psychiatric symptoms and conspiracies of silence. It is concluded that public policies to avoid the “war on” notion are required. Instead, education of the general population about wrong beliefs about cancer should be encouraged. (This article discusses the origin and implications of the “war on cancer” metaphor. Commonly present in mass media, the “war on cancer” notion circulates also among patients, their loved ones, their support networks, and oncological multidisciplinary teams. In our view when cancer is uprooted of its illness status, and conceptualized as an “enemy”, myths about disease and those who suffer it (especially the idea of psychogenesis) are strengthened. Two topics in which the war metaphor is particularly problematic in the clinical context, are analyzed in depth. The first one is the relationship between the oncologic patient with his loved ones and support networks. When patients are insistently prompted to fight the disease and think positive, the expression of emotions associated to the adaptive process of receiving a diagnosis of cancer are inhibited. Secondly, the war metaphor promotes an authoritarian view among the health teams and on the doctor-patient relationship, undermining the patent's autonomy in the decision-making process, which may affect his global quality of life. Also, it encourages emotional isolation, concealment of psychiatric symptoms and conspiracies of silence. It is concluded that public policies to avoid the “war on” notion are required. Instead, education of the general population about wrong beliefs about cancer should be encouraged.