The diagnosis of an advanced life-threatening illness brings with it existential challenges that activate the attachment system and different attachment styles influence coping with advanced illness.

The objective of this work were (a) to analyze the influence of attachment styles of patients with advanced disease and their relatives on emotional distress and other psychological and existential aspects, and (b) to identify the most used assessment instruments to measure it, highlighting those with better psychometric properties in palliative care contexts.

Articles on attachment published from October 2005 to February 2025 using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guide (PRISMA) were identified by searching PubMed, PsycINFO, Google Scholar, SCOPUS, Dialnet, and the Web of Science databases.

Of 1847 studies identified, 24 were included (21 quantitative and 53 qualitative). Quality assessment revealed low risk of bias and high methodological quality. The main results indicated that a secure attachment style was associated with better coping, adaptation and adjustment strategies to the experience of illness, causing a buffering effect on suffering at the end of life. In contrast, patients with insecure attachment styles presented higher levels of emotional distress, demoralization, existential loneliness, death anxiety and showed a poorer psychological adaptation to cancer. Almost two-thirds of the studies (65.1%) used some version of Experiences in Close Relationships (ECR) scale.

The attachment theory appears to offer a valuable conceptual framework for understanding how individuals may respond to the emotional and relational demands associated with advanced illness and end-of-life care. Its contributions have been increasingly considered in literature addressing psychosocial adjustment and coping in palliative contexts

For the assessment of attachment styles in a palliative context, the most used instrument is the original ECR-M16 scale or its iderived versions.