[Happiness and cancer].

Television, newspapers and social media suggest that cancer patients hold their fate in their own hands: they can improve their chances of survival by means of positive thinking or by adopting a fighting mentality. Nevertheless, there is no convincing scientific evidence of a link between one's personality or coping mechanisms and survival. Studies that do show a positive association are generally of inferior methodology and substantially smaller than studies with null findings. Psychotherapeutic interventions may improve the quality of life, lifestyle and treatment compliance in patients with cancer, but no randomized controlled trials or meta-analyses having survival as a primary endpoint have shown any positive effects of psychotherapy on survival. There is also no solid evidence that the 'cancer experience' does enrich one's life or lead to personal growth or happiness. In conclusion, positive thinking and a fighting mentality do not improve chances of survival, adequate treatment does.