Malignant diseases is a major public health problem worldwide, and according to the World Health Organization, malignant diseases are currently the leading cause of death after cardiovascular diseases. Diagnosis and treatment of malignant diseases causes emotional trauma and physical symptoms, and are the result of the diagnosis itself, which requires lifelong treatment with aggressive medical treatments and changes in the current way of life. Malignant disease is in itself life-threatening and causes a large amount of stress. Psychiatric illnesses such as depression and anxiety are common, but often overlooked complications of cancer, which affect quality of life, adherence to treatment, cancer survival and treatment costs. Cancer treatment can be an insufficiently recognizable but reversible cause of severe and sometimes rapid onset of mental illness. Advanced malignancy is incurable and causes insecurity, suffering, existential fear, difficulty making decisions and poor physical functioning. It is treated as a chronic disease requiring palliative care and exceptional support and participation of friends and family in the treatment process. Psycho-oncological foundations represent a series of reactions, procedures, exchanges and encounters concerning the relationship between the patient and the environment and the endurance of one's own illness. They include the relationship between the patient and the family as well as the mutual communication of the patient and the medical staff accompanying the patient in the diagnostic and therapeutic procedure. Psychological help is gaining great importance in oncology treatment, from the process of communicating the diagnosis all the way to the terminal phase of the disease. Training and guidance of professional staff, including nurses, social workers, psychiatrists, psychologists and priests ensures the provision of psychosocial care services to patients of various theoretical orientations, theoretical orientations and available resources. The providing of health care of nurses in oncology encompasses all treatment procedures including diagnosis, possible relapses, a period of palliative care and a peaceful and dignified death in the terminal phase of the disease. It is primarily necessary to know the disease, manifestation of the disease, the manner of performing and conducting health care. The major challenges, that nurses face, are largely related to communication and social skills, as well as empathy and an empathetic approach to treatment. Cancer sufferers are certainly among the most vulnerable people, both physically and psychologically. That is why it is very important to provide psychological help from the very beginning and the encounter with the diagnosis of this disease.