Universität zu Köln

Schomberg, Jan ORCID: 0000-0002-1928-1653 (2026). The Significance of the Interpersonal-Psychological Theory of Suicide in an Oncological Context. PhD thesis, Universität zu Köln.

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Abstract

Suicide is a major global public health concern, responsible for over 700,000 deaths annually and ranking as the fourth leading cause of death among individuals aged 15–29 years. The complexity of suicidality, encompassing suicidal ideation (SI), plans, attempts, and completed suicide, underscores the need for robust theoretical frameworks and reliable assessment tools to better understand and address this critical issue. Cancer patients face a heightened risk of suicide, with rates nearly double those of the general population. This increased vulnerability is influenced by a combination of medical, psychological, and social factors. This dissertation explores the relevance of the Interpersonal-Psychological Theory of Suicide (IPTS) in an oncological context, aiming to enhance the assessment and understanding of suicide risk among cancer patients. The dissertation comprises three empirical studies, each contributing to the overarching goal of advancing research and clinical practice in suicidality. The first study presents the initial validation of the German version of the Suicide Attempt Self-Injury Interview (SASII). This research evaluates the psychometric properties of the SASII, including its factor structure, internal consistency, and construct validity, using a sample of N = 240 psychiatric inpatients. Despite limitations in subscale reliability, the findings suggest that the German SASII holds potential for clinical practice by offering a structured approach to assessing suicide risk and self-injury behaviors. The second study is a scoping review of the IPTS within an oncological context. This review synthesizes existing research to underscore the relevance of the IPTS in understanding suicide risk among cancer patients. It identifies four studies involving N = 915 cancer patients and highlights significant associations between the components of the IPTS and SI or behavior. The review calls for further empirical validation and longitudinal studies to address existing gaps in the literature. The third study represents the first peer-reviewed empirical test of the IPTS in a cohort of female cancer patients (N = 199). This research examines the relationships between key III theoretical constructs such as Thwarted Belongingness, Perceived Burdensomeness, and SI. The findings provide partial support for the IPTS. Unexpectedly, the study found that higher fear of death was associated with increased suicidal intent, suggesting a relationship that warrants further investigation. This finding also opens avenues for developing therapeutic interventions specifically targeting fear of death, which may help reduce SI in patients with cancer. Collectively, these studies contribute to a deeper understanding of the psychological factors influencing suicidality in cancer patients. They provide an assessment tool and empirically supported framework that can advance the understanding and treatment of suicidality in clinical settings. Finally, this dissertation emphasizes the importance of a collaborative, patient-centered approach to suicidality assessment and intervention, ultimately aiming to improve patient outcomes and advance the care of those experiencing SI or in suicidal crisis.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Schomberg, Jan jan.schomberg@rub.de https://orcid.org/0000-0002-1928-1653 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-809492
Date:	2026
Language:	English
Faculty:	Faculty of Human Sciences
Divisions:	Faculty of Human Sciences > Department Psychologie
Subjects:	Psychology
Uncontrolled Keywords:	Keywords Language Cancer, Suicide, IPTS, Interpersonal-Psychological Theory of Suicide, Oncology UNSPECIFIED
Date of oral exam:	17 July 2026
Referee:	Name Academic Title Gerlach, Alexander Prof. Dr. Cwik, Jan Prof. Dr. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/80949