A new prospective study has reported that a history of stress does not increase the risk of breast cancer. The study included 11,467 women with no history of breast cancer in the European Prospective Investigation into Cancer (EPIC)-Norfolk prospective cohort. Participants completed a comprehensive assessment of lifetime social adversity events and exposures, including difficult circumstances in childhood, stressful life events and longer-term difficulties in adulthood. The subjective impact of stressful events on participants and ability to deal with stress, as well as perceived stress over a 10-year period were also evaluated.

During a median follow-up period of nine years, 313 breast cancer diagnoses occurred in the study group. No associations were found between any of the stress measures and risk of breast cancer. These findings held even after adjustment for age, age at first period, age at first birth, number of children, menopausal status, use of hormone replacement therapy, family history of breast cancer, level of physical activity, social class, body mass index, height, or alcohol intake. The study also found no evidence that individual differences in the experience of stress are associated with the development of breast cancer.

Results confirm previous findings regarding stressful events

This study confirms previous findings that stressful life events are not associated with heightened risk of breast cancer. These include trauma during childhood and emotionally devasting events during adulthood such as the loss of a child. The implication is that emotional stress does not contribute to DNA damage that could lead to breast cancer, nor does it appear to be detrimental to the functioning of the parts of the immune system that may be involved in suppressing cancer. While the finding may be surprising to some, it will be a relief to others.

Is there a breast cancer personality?

Another commonly held belief is that certain personality traits are more prevalent among women who develop breast cancer. While a possible connection between stress and breast cancer is plausible, it is difficult to devise a mechanism of action that would account for an association between specific personality traits or a "cancer personality" and risk of breast cancer. In fact, no such connection has been found in the numerous studies that have been undertaken to examine this question.

What about stress or personality and breast cancer survival?

Stress and personality are likely to affect breast cancer treatment and survivorship in several ways. Perhaps one of the obvious effects of a high level of stress or a personality that does not incorporate superior coping skills is an inability navigate breast cancer diagnosis and treatment in an optimal fashion. Unless a woman's breast cancer is remarkably uncomplicated (i.e., a single, small, node-negative, early-stage hormone receptor positive tumor that can be treated with lumpectomy followed by radiation), there are likely to be a number of important decisions to be made regarding treatment and the women herself may have to exert some effort to obtain appropriate treatment in a timely manner.

While ideally there will be a member of a the cancer treatment team to guide a patient through this process, in practice this seldom occurs. A detour into alternative cancer treatment (such as an attempt to cure the cancer with a specialized diet), triggered in part by anxiety about treatments such as surgery, radiation or chemotherapy, can also result in a suboptimal outcome for those who would need additional support to proceed immediately with the most effective available medical treatments. Delays in treatment, for whatever the reason, can potentially result in a suboptimal long-term outcome, especially for those with aggressive types of breast cancer. However, there have not been many studies that have attempted to assess the impact of level of stress or personality on long-term survival from breast cancer.