Background: The relationship between mental health, quality of life (QOL) and cancer risk/mortality has not been adequately investigated. Psycho-neuro-immunology model has been hypothesized to provide links between psychological and physiological features of cancer risk/progression. Published findings are inconclusive.
Objective: This thesis aimed to examine the association between psychological factors and cancer risk/mortality in elderly population (STUDY I&II;), describe QOL in long-term cancer survivors (STUDY III), demonstrate response shift phenomena (STUDY IV) and explore psycho-neuro-immunological model between depression, cancer and ageing through inflammatory cytokines (STUDY V).
Methods: The studies were based on data from three population-based cohorts in Singapore: the Singapore Longitudinal Aging Study (SLAS) (STUDY I, III & V), the National Mental Health Survey of the Elderly (NMHS-E) (STUDY II), and breast cancer patients recruited from National Cancer Centre (STUDY IV). Depression was determined by the Geriatric Mental State (GMS), and Geriatric Depression Scale (GDS). QOL was assessed by Functional Assessment of Cancer Therapy – Breast (FACT-B) in breast cancer patients. Inflammatory cytokines assessed including Tumour Necrosis Factor Alpha (TNF-á), interleukin-6 (IL-6) and C-reactive protein (CRP).
Results: STUDY I: Poor self-reported mental health was significantly associated with an elevated risk of overall cancer incidence (HR=1.42), in female breast cancer (HR=2.96), and in male lung cancer (HR=3.45).
STUDY II: Depression was significantly associated with increased mortality hazard (HR=2.38) in cancer survivors. The mortality risk associated with depression among longterm cancer survivors who did not die within 5 years after diagnosis remained substantially high (HR=4.69). In particular, depression was associated with increased mortality in female breast cancer survivors (HR=11.6).
STUDY III: Long-term cancer survivors showed no statistical significant difference in QOL, life satisfaction level and depression level compared with their age-matched counterparts without cancer history.
STUDY IV: (1) Recalibration: Comparing current and Then-test QOL total scores of FACTB, statistically significant different was only shown during chemotherapy period. Thentest QOL score was significantly lower than current score, indicating worse QOL level. (2) Repriorization: There were statistically significant changes in the importance of PWB, EWB and FWB domains over the four assessments. (3) Reconceptualization: Financial concern was the most common concern mentioned except disease prognosis. At later assessment periods, the concerns were shifted to spiritual aspects, career prospects and mental well-being.
STUDY V: Statistically significant difference of TNF- á level was found between elderly with/without depression. After stratifying depression into three levels, TNF-á level was significantly associated with depressive level. After grouping participants by age and depression, TNF-á level in old-old with depression group were significantly higher than the others after adjusting for confounding variables. There was no significant association of cancer history with cytokines.
Conclusions: Psychological factors, especially depression, should be considered as a prognostic marker of cancer risk/survival in elderly population. Long-term cancer survivors reported similar QOL to their age-matched non-cancer counterparts. QOL is clearly affected by response shift, which may have an important impact on the interpretation of HRQOL changes. Inflammatory cytokine, elevated with depression, provides evidence base for the hypothesis that psychological intervention may enhance functional immunity, and confer survival benefits.
|School:||National University of Singapore (Singapore)|
|School Location:||Republic of Singapore|
|Source:||DAI-B 77/06(E), Dissertation Abstracts International|
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