ObjectiveIdentify the trajectories of physical and mental functioning among spouse caregivers of patients with cancer over the first five years post-diagnosis and variables associated with low or deteriorating functioning. MethodsCaregivers completed a survey at 6 months and 1, 2, 3.5, and 5 years post-patient diagnosis, including the SF-12 for quality of life (QOL). SF-12 Mental Component Summary (MCS, n=299) and Physical Component Summary (PCS, n=300) scores were analyzed using SAS. ResultsFive trajectories for PCS were identified, the top three were: (a) high PCS (53.0%); (b) steady decline in PCS (17.0%); and (c) steady increase, but remaining below population norm (16.7%). Five trajectories for MCS were also identified, the top two being: (a) high MCS (45.8%) and (b) MCS comparable to population norm (27.8%). Variables associated with low or deteriorating QOL included depression, social support, coping, burden, and/or unmet needs. ConclusionsThis is the first study to document spouse caregivers’ QOL over the first five years post-patient diagnosis. Although many participants experienced high functioning, almost a third reported low or deteriorating mental or physical functioning. Practice implicationsVariables associated with low or deteriorating mental and physical functioning can be targeted in future interventions.