Cancer is one of the biggest health challenges of our times, affecting all the personal areas of a patient. The interrelationships between these areas and the need for multidisciplinary care require the assessment of psychosocial complexity in cancer patients. The main aim of this study was to reach a consensus on the general definition of psychosocial complexity in cancer and its main elements according to the experts in the field.

A Delphi study was performed, which first involved a comprehensive review of the literature to create a questionnaire that was validated by two expert panels. The first panel consisted of intra-institutional experts, while the second included extra-institutional experts in the field. The study included three more rounds: (1) validation of the questionnaire by the internal panel, (2) discussion of the results and resolving discrepancies, and (3) validation of the questionnaire by the external panel.

After the four-round Delphi process, we obtained a consensus definition of psychosocial complexity in cancer patients, as well as of its main factors: medical–physical, social-family, psychological, and spiritual. A 21-indicators list and its 8-indicators brief version were also proposed as indicators of psychosocial complexity.

We present a definition of psychosocial complexity in cancer patients that has been agreed by experts, also establishing its four factors: medical–physical, social-family, psychological, and spiritual. This has led to the development of a list of indicators (and its brief version) that, after a validation process, could help health professionals to identify patients with high psychosocial complexity to provide them an optimal care.