Relationships Among Symptoms, Brain-Derived Neurotrophic Factor (BDNF), Daily Activities, Self-Care, and Quality of Life in Breast Cancer Survivors

Abstract

Background: Breast cancer survivors confront ongoing symptoms following diagnosis and treatment. Studies examining the relationship between biomarkers and symptoms are scarce. Purpose: To explore symptom occurrence and severity as reported by breast cancer survivors and their relationship to the BDNF Val66Met SNP (a biomarker), daily activities, quality of life and other selected subject characteristics and health variables. In addition, self-care methods used by survivors to alleviate symptoms and perceptions of the methods¡¯ usefulness were considered. Methods: Breast cancer survivors (6 months or more post-treatment) were invited by a coalition from a Mid-Atlantic state to participate in an online survey in Phase 1 (N = 195). The survey results provided the basis for a purposive sub-sampling. In Phase 2, two groups were identified from their scores on the Therapy-Related Symptoms Checklist (TRSC; low-scoring [¡Ü 14, n = 26] and high-scoring [¡Ý 23, n = 25]) for BDNF genotyping (by the Taqman probe assay) and exploration of self-care. All self-report tools have good psychometric properties: the TRSC, Daily Activities Rating (DAR), Health-Related Quality of Life-Linear Analogue Scale Assessment (HRQOL-LASA), and Symptom Alleviation: Self-Care Methods (SA: SCM). Fisher¡¯s exact test, logistic and multiple regression, and descriptive and content analyses were conducted. Findings: (a) The presence of the BDNF Val66Met SNP biomarker was related to lower symptom scores, but effect size was small and the relationship did not persist when controlling for confounders; (b) TRSC scores were not impacted by time since completion of treatment; (c) high total scores on the TRSC (high symptom occurrence and severity) were significantly related to high scores on the DAR (difficulty with activities of daily life) and to lower quality of life on the HRQOL-LASA; (d) the odds of a low TRSC score increased with increased education and increased age, and diminished if treatment included chemotherapy; (e) the self-care method used most commonly was diet/nutrition/lifestyle; the least common was herbs/vitamins/complementary therapy, and the methods that were used were perceived as effective. Clinical Implications and Need for Further Research: Beginning evidence that the BDNF Val66Met SNP may have a protective effect for ongoing symptoms in breast cancer survivors.