Social isolation and overall well-being among cancer survivors in the Cancer Prevention Study-3.

purposeSocial isolation is associated with poor health and sleep in the general population. However, its impact among cancer survivors-particularly as more individuals are living longer after a cancer diagnosis-remains unclear. We examined cross-sectional associations of social isolation with mental and physical health and sleep among cancer survivors ≤ 3 years ("shorter-term") and > 3 years post-diagnosis ("longer-term"), and cancer-free participants, using data from the American Cancer Society's Cancer Prevention Study-3 (CPS-3).

methodsAmong 2,290 shorter-term, 1,885 longer-term survivors, and 12,525 age-matched controls who completed the 2018 CPS-3 survey, multivariable-adjusted ANCOVAs evaluated associations between self-reported social isolation (Social Network Index), mental and physical health (PROMIS Global Health Scale), and sleep quality (single-item; PSQI).

resultsParticipants' mean age in 2018 was 60 years (SD = 8); 76% were female and 90% non-Hispanic White. Overall, 32% reported moderate-to-high social isolation, with similar proportions across shorter-term survivors, longer-term survivors, and controls. Higher social isolation was consistently associated with clinically meaningful lower mental health scores (poorer outcome) across all 3 groups. Longer-term survivors with high vs. low social isolation had significantly lower mental health scores by 5.8 units; this difference in mental health scores was statistically significantly larger than the corresponding differences among shorter-term survivors (-4.1 units; p < 0.001) and controls (-5.2 units; p = 0.03). Specifically, longer-term survivors who were older (≥ 65 years; difference = -7.0 units) or less physically active (< 15 MET-hr/wk; difference = -6.2 units) showed the largest differences in mental health scores when comparing high vs. low social isolation. No clinically meaningful associations were observed for physical health or sleep quality.

conclusionsHigher social isolation had the strongest associations with worse mental health among longer-term survivors, especially those who were older or less active. IMPLICATIONS FOR CANCER SURVIVORS: These findings highlight the importance of routine screening for social isolation and the need for targeted psychosocial programs to improve well-being among survivors, particularly those living longer who may be most affected.