Looking for links between stress and breast cancer

Researchers have tried to link stressful life events with the development of breast cancer in older women -- but past results have been mixed^{1 2}. Most studies show no connection³. The few studies that have found links between stress and the development of breast cancer have looked at only one or two individual factors, such as social support or a woman's ability to cope. ("Social support" describes the positive feelings of support, warmth, and love received from another person.)

This study, conducted in Australia, attempted to take a broader and more complete view of possible psychological risk factors for breast cancer. Researchers found only one combination of events that seemed to contribute to the risk of developing breast cancer -- having a catastrophic life event (or stress), such as the death of a child or a major financial crisis, within the same 2-year period as the loss of "intimate" social support, such as being widowed or going through a divorce. These results help debunk the commonly held myth that stress or personality traits by themselves can cause cancer.

This study was intentionally broad in scope. In order to understand the effects of major life stresses more clearly, researchers asked a wide range of questions about the personality traits and levels of social support that are considered to be helpful in helping people cope with stress. The questions covered topics such as: style of coping; the ability to express one's self emotionally; self-esteem; anxiety; depression; "intimate" emotional support (such as that received from a husband or other partner); "non-intimate" emotional support (such as that received from close friends and family); and information regarding both short-term (under 6 months) and long-term (over 6 months) stresses that happened over the last two years.

Scope and aim of the study

Australian women who participated in this study were all over 40 years old, with an average age of 56. The 2,224 women were recruited for the study from routine breast cancer screening programs in their communities. Participants completed the research questionnaires before being told their diagnosis. This increased the likelihood that the women would be more accurate in recalling events in their lives. Otherwise, if participants were asked to fill out questionnaires after receiving a diagnosis, it is likely that their memories and responses to questions would have been influenced by the strong emotions that often occur after learning that one has cancer -- and this would have increased the chances of getting inaccurate information.

Participants were also asked about some well-established risk factors for developing breast cancer such as family history, age when starting menopause, and whether or not women gave birth to their first child after the age of 29. Women were excluded from the study if they had a prior history of breast cancer, were already showing symptoms of the disease, or if they had already been told they had developed cancer.

Only one link found

Researchers included a wide range of possible risk factors in this complex study, but found only one combination that appears to be linked with an increase in development of breast cancer -- having an extremely stressful life event, such as death in the immediate family, in the same 2-year period as loss of "intimate" support, such as being widowed or divorced. Both factors had to be present in order for a woman to be at increased risk of developing breast cancer. Neither the stress by itself nor the loss of support by itself was enough to increase the risk of developing breast cancer. Also, bereavement alone was not linked to a higher cancer risk. But the combination of stressful events was significant, as it was associated with a nine-fold increase in the likelihood of women over 40 developing breast cancer.

Comment

The most important finding in this study is what researchers did not find -- they found almost no evidence to support the widely held myth that stress can be a direct cause of breast cancer development or progression. This study was also built on the same researchers' findings that the idea of a "Type C" cancer prone personality is false. (This is described in Part 1 of this article and can be reached via the link at the end of this page.)

The implications of these studies (Parts I and II) are important for two main reasons:

First, if a woman is already at risk of developing breast cancer, she can rest easier knowing that her risk will not be increased by stress levels, her particular personality or coping style, or lack of social support.

Second, women with breast cancer can rid themselves of any false blame they may have received from other people because of the myths that stress and personality ("Type C") cause cancer. The implication behind this kind of blame is that the women somehow brought their cancer onto themselves. This is simply not true. It is difficult enough to cope with a diagnosis of cancer without having unnecessary guilt imposed about personal and situational factors that, as it turns out, do not increase the risk of breast cancer.

Because the researchers included such a large number of possible contributing factors, it is even more remarkable that they found only one combination that was linked with the development of breast cancer. That one link is most relevant to older women facing the loss of "intimate" emotional support. Recently widowed or divorced older women may be at higher risk of developing breast cancer if the loss happens within 2 years of another major stressful life event, such as a death in the immediate family (i.e. involving someone other than their spouse) or catastrophic health concerns. It is important that physicians and family be aware of this possibility in order to do earlier or more intensive screening for breast cancer in those unusual cases where an older woman experiences multiple, devastating losses.

If you find that you are experiencing many severe stressful events, such as those outlined in this study, speak with your physician or other health care provider. You might also seek the services of a psychologist or other trained mental health professional in order to enhance your ability to cope with major stress.