Psycho-oncology is a branch of medicine which, combining psychiatry and oncology, studies the biological and psychological factors related to the onset and treatment of carcinoma. The struggle with this life-threatening disease requires an adaptation to a new life situation characterized by changed routines of everyday life and dynamics of personal relationships. The psycho-oncological approach is a multidisciplinary one, as modern medicine recognizes more and more the role of spirituality in the treatment and recovery from various pathological conditions. Spirituality is the adaptive capability of intelligent beings to retain the will for life in spite of adversities and awareness of the imminence of death. Faced with a challenge of malignant disease people are nevertheless able to react with positive personality changes, which leads them to a more meaningful and substantial life. The so-called posttraumatic growth is a feature which enables an individual to assume control over his own reactions to disease, which in turn can have a positive influence on the treatment outcome. An essential role in this process is played by the spiritual growth of an individual. Malignant disease can represent an opportunity for spiritual growth, a dimension often neglected by contemporary lifestyles. Religion, as an important constituent part of spirituality, can offer the believer a meaning of suffering and thus turn the disease into an opportunity for self-knowledge and development of a more mature spirituality. Christian spirituality can represent a path which helps an individual to cope with malignant disease. Modern medicine should be based on a multidisciplinary approach to the patient and encompass all the human dimensions (rational, emotional and spiritual), whereas treatment itself must be both personalized and participatory.