Can Stress Affect Cancer?

Stress is generally defined as a condition in which the body or mind is placed under strain or tension. Stress is a normal part of life: In fact, studies show it to be a necessary part of life, prompting us to adapt and become more resilient. But if it becomes excessive, stress can have adverse physical as well as psychological consequences.

For cancer patients, psychological stress adds to the burden imposed by the disease and the sometimes difficult aspects of treatment. Researchers have begun to explore whether, and in what ways, stress can affect the course of the disease.

The evidence

According to the National Cancer Institute (NCI), there’s no solid evidence that stress can cause cancer. “Some studies have indicated a link between various psychological factors and an increased risk of developing cancer, but others have not,” the NCI website states.

While relaxation and stress-management techniques can certainly enhance patients’ quality of life, there’s little to suggest that these practices improve cancer survival, according to the NCI. Patients have reported that certain integrative therapies, including acupuncture, can help them manage the symptoms and side effects associated with cancer.

Studies in animal models

Some studies have suggested that psychological stress can affect a tumor’s ability to grow and spread. In studies of mice carrying human tumors, researchers found that in mice isolated from other mice – a condition that increases stress – the tumors were more likely to grow and metastasize.

“In one set of experiments, tumors transplanted into the mammary fat pads of mice had much higher rates of spread to the lungs and lymph nodes if the mice were chronically stressed than if the mice were not stressed. Studies in mice and in human cancer cells grown in the laboratory have found that the stress hormone norepinephrine, part of the body’s fight-or-flight response system, may promote angiogenesis [growth of tumor-supporting blood vessels] and metastasis,” the NCI reports.

Another animal study focused on prostate cancer. Mice were implanted with human prostate cancer cells and treated with a drug being tested against the disease. When the mice were kept in a calm condition, the drug destroyed the cancer cells and inhibited tumor growth. When they were put under stress, however, the cancer cells did not die and tumor growth surged ahead.

In a similar study involving mice genetically prone to developing prostate cancer, the results were much the same. The researchers traced the result to adrenaline, a stress hormone that shuts down the natural death process in cancer cells.

A few studies have looked at the question of stress and cancer growth in human patients. In one, researchers analyzed 80 ovarian cancer tissue samples grouped by the stress levels of the patients from whom the samples were taken. Stress, along with elevated stress hormones, were associated with higher levels of a protein called FAK (focal adhesion kinase), which is linked to faster progression of the disease.

In another study, women with triple-negative breast cancer who had received chemotherapy prior to surgery were asked about their use of beta blockers, medications that interfere with certain stress hormones. Women who reported using beta blockers had a better chance of surviving their cancer treatment without a relapse than women who didn’t report beta blocker use. There was no difference, however, between the two groups in terms of overall survival, the NCI states.

Overall, stress has not been clearly shown to worsen the course of disease in patients with cancer, but there’s no question that reducing stress can help people cope more effectively with a cancer diagnosis.