PURPOSE Although surrogate decision-making in cancer patients is well-known, few studies investigating the prevalence of surrogate decision-making over time have been reported. The objectives of this study were to investigate the level of surrogate decision-making in advanced cancer patients over time and the impact of demographic and clinical variables on surrogate decision-making.

METHODS The level of surrogate decision-making was measured in 572 consecutive cancer patients who died between January 1 and December 31, 2009. We reviewed 8,639 informed consent forms of these patients, calculated the proportion of decisions made by a surrogate (PDS) for each patient, and analyzed the association of PDS with demographic and clinical variables.

RESULTS Surrogates completed 40.3 % of all consent forms. The prevalence of surrogate decision-making was higher in the end-of-life period (death <7 days, OR = 29.05; reference, >365 days). Surrogates signed consent forms more frequently for do-not-resuscitate directives, intensive care unit admission, emergency hemodialysis, surgery and invasive interventions compared with chemotherapy, radiotherapy, and diagnostic tests (OR = 3.88, P < 0.001). Patients of older age (P = 0.036) and those with a shorter duration of management (P < 0.001) were independently associated with greater PDS.

CONCLUSIONS Surrogate decision-making was frequently observed among Korean cancer patients in this study, especially when the patient's death was imminent, and for decisions related to end-of-life care. Surrogates were also frequently involved in decisions for elderly or rapidly deteriorating patients. Healthcare professionals should consider the significant role of familial surrogates in the end-of-life period; comprehensive approaches are needed to preserve the best interest of the patients.