The primary thesis of this doctoral dissertation, titled Anthropology of a Contemporary Rite of Passage –Elements of Initiation in Cancer Patients, posits that cancer represents an aspect of existential crisis that facilitates the experience of symbolic death and a qualitatively positive change in the patient's personality. As a psychiatrist-psycho-oncologist, I approached cancer from a cultural anthropological standpoint and recognized its broader implications beyond the biomedical model. Through the lens of cancer diagnosis, the suffering and pain from treatment side effects, and the experience of relapse and metastasis as symbolic deaths for oncology patients presented the main research focus. This research revealed the transformational role of cancer, which often goes unnoticed in the biomedical field. Viewing cancer as a sudden rupture in life, patients navigate a borderline period, experiencing personal and social drama, and develop individual approaches, thoughts, and coping mechanisms. They tap into personal imagination, utilize personal beliefs and practices as integral parts of treatment, report significant dreams, and undergo symbolic death, all of which lead to profound changes upon reintegration into everyday life. I aimed to explore to what extent the oncological practices, rituals, disruptions to their usual lives, and the trials endured during treatment, mirror or resemble elements of initiation rites found in structured, socially accepted forms of transition. I compared those experiences to indigenous maturation initiations, religious rituals, and shamanism, all of which embody the pattern of symbolic death and the transition to a new status. This dissertation comprises an introduction, eighteen chapters, a conclusion, and a bibliography. The first chapter provides an interdisciplinary overview of previous research in rites of passage, initiation, symbols, communitas, medical anthropology, and biomedicine relevant to oncology. Subsequent chapters delineate research objectives, hypotheses, expected scientific contributions, methodology, data collection, and the narrator's experiences structured around treatment events. The chapters delve into interpretations of initiation structure and function, general specifics of initiation complexes, shamanism, initiation rites in the Greek Christian world, the biomedical model of cancer, pre-cancer life, the significance of mastectomy-related pain and suffering, personal practices and rituals developed in response to chemotherapy, dreams and their meanings, individual therapy sessions, group work, and the autoethnographic perspective. The main aim of this disertation was to offer the fieldwork-based analysis of the implications of recognizing symbolic death and positive transformation for oncology patients and the potential improvement of current biomedical approaches to cancer. The conclusion confirms the initial thesis that cancer has the capacity to foster positive evaluation and personality transformation. This interdisciplinary doctoral work aims not only to advance medical anthropology but also to integrate its findings into oncology treatment practice for the benefit of patients, medicine, and society at large.