Relationship between stress and breast cancer

Women diagnosed with metastatic breast cancer who have also endured previous traumatic or stressful events see their cancer recur nearly twice as fast as other women, according to a report by a University of Rochester Medical Center scientist.

The small, retrospective study showed that women who faced physical or sexual abuse or life-threatening situations see metastatic tumors return after about 2.5 years, compared with women who have more peaceful lives, who see recurrence at about five years. The report was published in this month's Journal of Psychosomatic Research by scientists from the University of Rochester Medical Center and Stanford University School of Medicine.

While some of the reported events are less common than others, they all took a toll on the women and, scientists believe, may have contributed to the recurrence of disease.

“There is such a dramatic difference between women who had experienced traumatic things and those who didn't,” said Oxana Palesh, Ph.D., first author of the study and research assistant professor of Radiation Oncology and Psychiatry at the James P. Wilmot Cancer Center at the University of Rochester Medical Center. “Clearly this study demonstrates that it's important to recover from trauma or stressful event for your mental and physical health.”

The relationship between stress and breast cancer has been heavily studied, however the results are murky. Studies have shown that stress can alter the immune system's function, and that the activity of natural killer cells is related to breast cancer progression. But scientists have had more difficulty showing a link between stress and the development of breast cancer. Some large-scale studies have shown connections between recent stressful life events, such as the death of a spouse, and breast cancer risk, while others have not. Scientists are intrigued by the conflicting evidence, and research continues.

In this most recent effort, the bi-coastal team interviewed 94 women from the San Francisco Bay area and categorized their life experiences as either traumatic or stressful, and compared them with a control group of women who had not faced similar situations. The participants reported traumatic experiences such as childhood sexual abuse, rape, suicide of a family member or life-threatening injury. Stressful events included adoption, parent's death, living with their mother-in-law, earthquake, divorce or having a family member imprisoned.

In the three study groups, 39 women reported traumatic events in their history, and median disease-free interval was 2.5 years; for 27 women who had experienced stressful situations, it was 37 months – just over three years. And in the final group of 28 women who reported no stress or trauma in their history, the median disease-free interval was 62 months – just over five years.

All of the women were diagnosed in their late 40s, and 85 percent of them were white. Demographic analysis showed that 69 percent were married, and 19 of the women in the stressed and traumatic groups were divorced or widowed.

The research also involved analysis of cortisol levels from saliva samples from participants. Cortisol is produced when the body faces periods of stress, and there is growing evidence that abnormally prolonged cortisol production inhibits the body's immune response. This could potentially make the body more susceptible to recurrence of cancer, Palesh said.

“Extended periods of stress and trauma and its resulting cortisol production may interfere with the body's ability to fight off cancer progression,” said Palesh. “When there is consistent, long-term stress in the body, the elevated cortisol level may can change the body's normal rhythms and potentially reduce resistance to tumor growth.”