The use of stringent sets of diagnostic criteria often represents a daily clinical challenge for mental health professionals caring for cancer patients. Many nosological classification systems were not specifically developed to meet the peculiarities associated with the emotional experience of cancer. In particular, the diagnosis of adjustment disorder according to the Diagnostic and Statistical Manual of mental disorders appears inappropriate in this context. It is questionable, indeed, how to assess the "excessive" nature of psychological distress ari-sing in response to such a burdening event as a cancer diagnosis. Furthermore, the conceptual validity of the adjustment disorder construct may be of poor clinical relevance in patients suffering from a life-threatening medical condition and its widespread consequences. In this paper, we intend to offer an operational definition of adjustment and we argue that a vast majority of cancer patients currently receiving a diagnosis of adjustment disorder actually suffer from either subthreshold depression or from full or partial presentation of post-traumatic stress disorder. We first briefly review some available models of psychological adaptation. We also argue that trying to explain the experience of cancer alongside a continuum of psychological distress does not help us to better understand underlying adjustment processes and to treat emotional disturbances more effectively. The literature is currently scanty about the critical role of a psychological trauma, namely the diagnosis of cancer, in generating emotional, cognitive and behavioral responses. The very fact that an average of 10% of cancer patients have been shown to meet criteria for PTSD might suggest that the existence of a specific trauma stress adaptation process in this particular patient population. The confirmation of these hypotheses by clinical observation, experimental psychology paradigms or functional brain imagery studies could have substantial implications for the treatment of psychological distress in patients with cancer. Issues such as the relevance of pharmacological treatment of subthreshold depression--which has received little attention in the general literature--or the role of psychodynamic approaches in the management of cancer-related traumatic dimensions, should be addressed systematically.