Objective: The objective of this works is to report the results of a systematic review to evaluate the role of attachment in adjustment to cancer for patients and those close to them. Methods: A systematic search of electronic databases was undertaken, identifying literature published up to June 2013. PsychINFO, Medline and the Cumulative Index to Nursing & Allied Health Literature were searched using search strings related to cancer, relationships, attachment and commonly assessed self-report psychosocial outcome measures. Extracted papers were assessed for their relevance. Key data were extracted to spreadsheets, and two raters coded the quality of the research. Results: Following inclusion assessment, data were extracted from 15 quantitative studies. Scores from patients or caregivers on attachment questionnaires did not differ greatly from normative data. A more insecure attachment style has poorer outcomes for patients in terms of their psychological adjustment to cancer and their ability to perceive and access social support. A secure attachment style is associated with positive growth and better well-being. A more insecure attachment style in caregivers was associated with depression, higher caregiving stress, less autonomous motivations for caregiving and difficulties with caregiving. Conclusions: An awareness of attachment theory and the ways in which different forms of insecure attachment impact on patients and caregivers and their well-being may substantially improve the ability of those working with cancer patients and their families to better understand and provide for their support needs. The development and evaluation of support interventions tailored to different attachment styles remains a longer-term goal.