Abstract 1927: Differential effects of social isolation on cancer mortality by race/ethnicity and socioeconomic status among working age adults in the United States
Authors: Lee Hyunjung , Singh Gopal K. , Jemal Ahmedin , Islami Farhad 
Published: April 2023

Background Social isolation or living alone can negatively affect mental health, sleep quality, eating behavior, immunity, proinflammatory response to stress, and receipt of care in cancer patients (e.g., assistance with nutrition and mobility, emotional and informational support), which may increase the risk of death from cancer. Previous studies, however, have shown inconsistent findings on the association between social isolation and cancer mortality. To address the literature gap, we examined this association among working-age adults stratified by sociodemographic characteristics using a nationally representative cohort with long-term mortality follow-up.

Method We used the pooled 1998-2019 data for adults aged 18-64 years at enrollment from the National Health Interview Survey (NHIS) linked to National Death Index (N=473,648) with up to 22 years of follow-up. Cox proportional hazards regression was used to model survival time as a function of social isolation, measured by “living alone”, and sociodemographic, behavioral, and health characteristics. We estimated differential effects of social isolation on cancer mortality by age, sex, race/ethnicity, poverty level, and education, overall and for select common cancers (lung, colorectal, and female breast) with &gt;100 deaths in the public use NHIS-linked mortality database, 1998-2004.

Results The cancer mortality risk was 32% higher (hazard ratio [HR]=1.32; 95%CI:1.25,1.39) in adults living alone, controlling for age, and 16% higher (HR=1.16; 95%CI:1.10,1.23) in adults living alone, controlling for demographic and socioeconomic characteristics, when compared to adults living with others. The association between living alone and cancer mortality persisted after additional adjustments for health-risk behaviors and health status (HR=1.10, 95%CI:1.04,1.16). Stratified models generally showed similar associations between social isolation and cancer mortality risk across categories of sex, poverty, and education in age-adjusted models. However, the association was stronger among non-Hispanic (NH) White than NH Black adults and did not exist in other racial/ethnic groups. The associations were attenuated after additional adjustments but persisted in fully adjusted models among males, females, NH White people, and adults with a college degree. In the age-adjusted models, social isolation was associated with a higher risk of death from lung (HR=1.45; 95%CI:1.81,2.45) and colorectal (HR=1.65; 95%CI:2.58,1.56), but not from female breast cancer.

Conclusions In this nationally representative study in the United States, adults living alone were at a higher risk of cancer death compared to adults living with others. These findings underscore the significance of addressing social isolation in the general population and among cancer survivors.

Citation Format: Hyunjung Lee, Gopal K. Singh, Ahmedin Jemal, Farhad Islami. Differential effects of social isolation on cancer mortality by race/ethnicity and socioeconomic status among working age adults in the United States [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1927.