Stress Reactivity Patterns in Breast Cancer Survivors and the Implications of Various Psychosocial Factors

Abstract

The stress system comprises the hypothalamic-pituitary-adrenal (HPA) and the sympathetic-adrenal-medullary (SAM) axes. The two operate synergistically to regulate metabolic and biological processes, maintain homeostasis, and manage physiological responses towards various environmental challenges, known as stressors. Numerous studies have observed impaired HPA response among White breast cancer survivors followed by an eventual normalization of the HPA axis, but little is known about SAM functioning, the complementary relationship between physiological and psychological stress, and the influence of culturally related factors. This dissertation aims to address these gaps in the literature via three studies. In Study 1, we examined the diurnal and reactive patterns of salivary alpha-amylase, a SAM biomarker, in a sample of predominantly White women with and without a prior diagnosis of breast cancer. The purpose was to establish an initial understanding of SAM functioning in relation to the participants’ HPA activity as measured by cortisol responses (complementary to a previously published study in the laboratory). Results of Study 1 revealed no abnormal response to stress. Virtually identical alpha-amylase slopes were observed between breast cancer survivors and control participants, except that breast cancer survivors had elevated basal levels of alpha-amylase, thus suggesting a “heightened sympathetic tone”. In Study 2 acute and diurnal cortisol profiles and their accompanying psychological stress responses were examined in a sample of Chinese and White women with and without a prior diagnosis of breast cancer. In the same participants, we also examined chronic stress levels via hair cortisol concentrations which was the subject of Study 3. In both studies 2 and 3, we assessed the potential influences of cultural orientation and ethnocultural group membership on physiological and psychological stress patterns. For the most part, Study 2 supported previous findings from the literature and our laboratory: Breast cancer survivors displayed a blunted cortisol response and their diurnal profile was comparable to that of control participants. But contrary to our hypotheses, ethnocultural membership and cultural orientation did not influence physiological patterns of stress. However, an interaction between ethnocultural group, health status, and time (i.e., from baseline to one hour after stress induction) was observed in the subjective appraisal of an acute stressor. Specifically, White breast cancer survivors reported significantly lower levels of perceived stress than the other three groups. These results suggest that health-related stress may supersede the effects of culturally related stress and indicate the potential presence of posttraumatic growth among our sample of White breast cancer survivors only. Study 3 revealed no differences in hair cortisol concentrations between breast cancer survivors and control participants, nor between Chinese and White breast cancer survivors. However, it was observed that healthy Chinese women exhibited significantly higher levels of hair cortisol concentrations than their Western counterpart. Further analyses revealed that health status and cultural orientation did not significantly predict the observed patterns of physiological or psychological stress. Although non-significant, Study 3 results offered preliminary evidence that higher orientation towards both the dominant and non-dominant cultures is associated with higher levels of chronic physiological and psychological stress. Collectively, our studies may provide support for the long-term recovery of the HPA axis via the examination of acute, diurnal, and chronic patterns of cortisol, but further research will be required. The dissertation also highlights several important key points regarding culturally related factors, health, and stress: (1) The perception of stress is influenced by one’s degree of cultural orientation and (2) effects of health-related stress may supersede those of culturally related stress, but (3) among healthy women, ethnocultural minorities may have more stressful encounters than their Western counterpart, thus having important clinical implications for ethnocultural minorities who are newly diagnosed with a chronic condition. Together, results of the studies highlight the importance of further investigating the enduring and acute implications of psychosocial variables – particularly the influence of cultural orientation – on the experience and perception of stress.