Abstract
BACKGROUND: Depression and diet are both common modifiable factors related to mortality rates among individuals with cancer, but their combined effects remained underexplored. We aimed to comprehensively evaluate the independent and joint association of depressive symptoms and dietary patterns with mortality among cancer survivors. METHODS: A cohort of US cancer survivors (3,011 eligible participants, representing 20 million cancer patients) were collected from the National Health and Nutrition Examination Survey (NHANES) between 2005 and 2018. Depressive symptoms were assessed with the Patient Health Questionnaire (PHQ-9). Based on dietary data from 24-hour recall, several well-developed dietary pattern indices were calculated, including Healthy Eating Index-2020 (HEI-2020), Alternative Healthy Eating Index (AHEI), Alternate Mediterranean Diet Score (aMED), MED Index in serving sizes from the PREDIMED trial (MEDI), Dietary Approaches to Stop Hypertension Index (DASH), DASH Index in serving sizes from the DASH trial (DASHI), Dietary Inflammation Index (DII), and DII excluding alcohol (DII [No EtOH]). Kaplan-Meier curves and multivariable Cox proportional hazards regression models were conducted to investigate the relationships of independent and combined prognostic effects of PHQ-9 score and dietary pattern indices with survival among cancer survivors. RESULTS: In joint analysis, combinations of lower PHQ-9 score with higher HEI-2020, AHEI, aMED or DASH were favorably linked to lower risks of overall and noncancer mortality. Representatively, cancer survivors with no to minimal depressive symptoms (PHQ-9 score: 0-4) and high adherence to the HEI-2020 had lower risk of all-cause (HR = 0.43, 95% CI: 0.24-0.75) and noncancer (HR = 0.29, 95% CI: 0.15-0.55) mortality, when compared to those with PHQ-9 score ≥ 10 and low adherence to the HEI-2020. Additionally, a combination of higher adherence to the MEDI and lower PHQ-9 scores was linked to a reduced risk of noncancer mortality. CONCLUSIONS: The joints of depressive symptoms and certain dietary patterns were associated with risks of all-cause, cancer-specific, and noncancer mortality among cancer survivors. Early psychological counseling and individualized dietary strategies are crucial to reduce mortality risk and improve quality of life for this population.