Epidemiological evidence for a relationship between life events, coping style, and personality factors in the development of breast cancer

Abstract

Objective: Review empirical evidence for a relationship between psychosocial factors and breast cancer development. Methods: Standardised quality assessment criteria were utilised to assess the evidence of psychosocial predictors of breast cancer development in the following domains: (a) stressful life events, (b) coping style, (c) social support, and (d) emotional and personality factors. Results: Few well-designed studies report any association between life events and breast cancer, the exception being two small studies using the Life Events and Difficulties Schedule (LEDS) reporting an association between severely threatening events and breast cancer risk. Seven studies show anger repression or alexithymia are predictors, the strongest evidence suggesting younger women are at increased risk. There is no evidence that social support, chronic anxiety, or depression affects breast cancer development. With the exception of rationality/anti-emotionality, personality factors do not predict breast cancer risk. Conclusion: The evidence for a relationship between psychosocial factors and breast cancer is weak. The strongest predictors are emotional repression and severe life events. Future research would benefit from theoretical grounding and greater methodological rigour. Recommendations are given.

Introduction

The notion that cancer might be related to stress or emotional factors can be traced back to around 200 AD when Galen noted that melancholic women were much more susceptible to cancer than other females [1]. In 1759, Guy, a surgeon, emphasised “such disasters in life, as occasion much trouble and grief” in the causation of cancer [2]. In the first half of this century the search focused on external explanations for illness, influenced by Descartes, who viewed the mind as distinctly separate and an unrelated entity from the mechanistic body.

Renewed interest in the mind–body relationship over the past three decades parallels our increasing understanding of the complex interrelationships between the immunological, endocrine, and nervous systems. There is mounting evidence that stress can disturb many areas of the immune system and that impaired immune system function predisposes to malignant growth [3], [4]. The impact of life event stress is related not only to the type and severity of the event itself, but may be modified by the availability of resources to deal with the demands. It is unclear whether psychosocial factors impact directly on endocrine, immune, and nervous systems or indirectly by affecting behaviours such as diet, exercise, sleep, etc., which themselves have links to endocrine and immune functioning [5], [6], [7]. Hilakivi-Clarke et al. [8] have developed a model in which life event stress, personality, and social support influence an individual's ability to cope, which in turn mediates breast cancer risk via alterations in neuroendocrine and immune functioning. These data and model provide an avenue for explaining clinical and epidemiological observations in this area, as well as the anecdotal reports of women who believe that “stress” or “depression” was a factor in the development of their cancer [9], [10].

There have been many review articles published in this area, some focusing on life events, others on the cancer prone personality, some covering psychosocial factors in disease onset, and some in outcome, while others are more theoretical in nature [5], [8], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20]. However, none of these reviews have attempted to integrate the literature in these disparate areas in a systematic manner. Furthermore, many have focused on cancer in general which may cloud the picture. Because cancer is a biologically diverse disease, it is unlikely that any single psychosocial factor, or set of factors, will be related in the same fashion to the onset of all cancers.

We have chosen to focus on breast cancer, being hormonally sensitive. Since “stress” is involved in activation of the endocrine system, it seems likely that psychosocial factors may potentially play a greater role in cancer of the breast than at other sites. This review focuses on the psychosocial factors thought to be related to the development of breast cancer; namely life events, coping style, affect, personality, and social support. These areas are clearly interrelated. Although they are at times measured together, rarely are their interactive effects examined. Therefore, each domain is considered separately and where possible their interrelationships are discussed. We have chosen to focus only on predictors of breast cancer development, rather than outcome, as the literature on the latter issue is as vast, with differing predictors and theoretical pathways.