Tumor dormancy and the neuroendocrine system: an undisclosed connection?

Tumor dormancy is a poorly understood phenomenon conceptualized as a protracted quiescent state during which cancer cells are present but clinical disease is not apparent, a condition referred to as "cancer without disease" by Folkman. Examples include the incidental detection of occult in situ tumors in post-mortem organ analysis and cancer recurrence after long disease-free periods. Lack of angiogenic competency has been proposed as a major determinant of the fate of dormant tumors. Other proposed processes include establishment of homeostatic equilibrium between tumor cells and the host's immune system response and a non-permissive microenvironment for tumor growth. Recent cellular and molecular studies suggest that neuroendocrine mediators regulate the biology of tumor progression and act as endogenous modulators of angiogenesis, inflammation, and other molecular processes involved in tumor reactivation from dormancy. We review experimental and clinical evidence and propose that neuroendocrine dynamics of the sympathetic nervous system and the hypothalamic-pituitary-adrenal axis might contribute to the loss of tumor dormancy.

Breast cancer survivors' health-related quality of life : racial differences and comparisons with noncancer controls.

BACKGROUND: Small samples with few minority women and/or the absence of comparisons to peers without cancer histories have limited previous research suggesting racial differences in breast cancer survivors' health-related quality of life (HRQoL). This study not only compared HRQoL of African American and white breast cancer survivors, but also compared the HRQoL of these women to that of same-race women with no cancer history. METHODS: Data from the Women's Health Initiative-Observational Study were used, including 5021 cancer survivors and 88,532 women without a history of cancer. Multivariate regression analyses estimated differences in breast cancer survivors' baseline HRQoL (RAND36), depressive symptoms (CES-D short-form), and sleep quality (WHIIRS). RESULTS: African American breast cancer survivors reported worse physical functioning and general health compared with white survivors. Among African Americans, survivors reported worse role limitations due to physical health, pain, general health, and vitality than women without a history of cancer. This was most evident in those with more recent diagnoses. Most significant differences between groups were small in magnitude (Cohen d = .21-.36). CONCLUSIONS: These results add to the increasing knowledge of cancer disparities by showing that African American women have small, but clinically meaningful, decrements in physical HRQoL compared with white survivors and with African American women without cancer. Because African American women also face diagnosis with higher grade tumors and higher breast cancer mortality, more research is needed to examine the physical and psychosocial experiences of African American breast cancer survivors to elucidate the mechanisms leading to poorer outcomes.

The influence of bio-behavioural factors on tumour biology: pathways and mechanisms.

Epidemiological studies indicate that stress, chronic depression and lack of social support might serve as risk factors for cancer development and progression. Recent cellular and molecular studies have identified biological processes that could potentially mediate such effects. This review integrates clinical, cellular and molecular studies to provide a mechanistic understanding of the interface between biological and behavioural influences in cancer, and identifies novel behavioural or pharmacological interventions that might help improve cancer outcomes.

A biobehavioral perspective of tumor biology.

Extract: The perspective that cancer may be causally linked to stress has a long history. In 200 AD, Galen proposed that melancholic women were more susceptible to cancer than women who were sanguine. Rigorous examinations of related observations have lagged over the ensuing centuries. More recently, epidemiologic studies have shown that psychologic and social characteristics (e.g., chronic stress and negative life events, social isolation and support, socioeconomic burden, and emotional processes) might be associated with differential cancer incidence, progression, and mortality. The biologic mechanisms (e.g., signaling pathways) that may account for such observations are being discovered through the convergence of relevant molecular, cellular, and clinical data. In this article, we review the clinical and experimental evidence regarding the effects of stress on tumor development, growth, and progression. Within this context, we define "stress" as an external event ("stressor") or perception of such events that engender psychologic and physiologic changes ("stress responses") designed to approach, avoid, or defend against the external event.

Religion, spirituality and cancer: current status and methodological challenges.

The role of religion and spirituality in health has received increasing attention in the scientific and lay literature. While the scientific attention to this issue has expanded, there continue to be methodological and measurement concerns that often prevent firm conclusions about health and adjustment benefits. Limited attention has been provided to the role of spirituality and religion in cancer. This is true when both disease outcome and adjustment are considered. A recent 'levels of evidence' review examining the link between physical health and religion or spirituality found little overall support for the hypotheses that religion or spirituality impact cancer progression or mortality. Studies examining their impact on quality of life and adjustment are decidedly mixed. In sum, research specifically focusing on the role of religion or spirituality on cancer outcomes has been surprisingly sparse. Such research presents a number of methodological and measurement challenges. Due to these unmet challenges in the literature to date, it is premature to determine what role religion and spirituality play in disease, adjustment, or quality of life outcomes in cancer. A number of suggestions are made for continued research in this area.

Minority recruitment in hereditary breast cancer research.

Although recruitment of ethnic and racial minorities in medical research has been evaluated in several studies, much less is known about the methods used to recruit these populations to participate in cancer genetics research. This report reviews the resources that have been used to identify and recruit ethnic and racial minorities to participate in hereditary breast cancer research. Overall, hospital-based resources were used most often to identify potential subjects, and active recruitment methods were used most frequently to enroll eligible subjects. This review suggests that there appears to be a finite number of resources and strategies to identify and recruit potential subjects to participate in cancer genetics research; however, options for improving awareness about cancer genetics research among ethnic and racial minorities have not been extensively evaluated. To study ethnic and racial minority participation in cancer genetics research, stronger evaluation components will need to be integrated into research methods. Both observational and experimental studies are needed to determine resources that are most effective for identifying potential subjects who are ethnic and racial minorities and to evaluate the effects of different recruitment strategies on enrollment decisions among these populations.