First some history so we understand how we got to where we are today (I’ll limit it to this last century). Around the turn of the century, Cannon was a Harvard physiologist who paid attention to some connections that he felt other investigators were ignoring at the time. He observed that all vertebrates had a common response to a threat which included increased heart and respiratory rates, tension in large muscle groups, coldness and sweatiness, decrease in intestinal activity, and dilatation of the pupils. All of these were manifestations of activity of the sympathetic nervous system (a part of the autonomic nervous system) which primes an animal (or human) to flee or fight. Common to all animals.
In the 1920-30’s, a physician by the name of Hans Selye made the next major contribution to mind-body medicine. He noticed that patients in a hospital all “looked sick” regardless of their specific illness. He set out to find the anatomic and physiologic commonalities among these sick looking patients. He subjected lab animals to all sorts of noxious stimuli (pain, loud noises, electric shock, heat and cold) and he found some consistent responses in all animals. The adrenal cortex (which secretes stress hormones) was enlarged and components of the immune system (such as the thymus, spleen, and lymph nodes) had shrunk. He defined “stress” as the non-specific response of the body to any demand, and the physiologic changes that he noted, he called the “general adaptation syndrome” or more commonly called the stress response today.
Now fast forward to the early 70’s when researchers were beginning to correlate fight or flight and stress responses with the development of certain diseases. Cardiologists Friedman and Rosenman described the angry, time-obsessed, hypertension and heart attack-prone “type A” executive. The type A person was in a chronic state of anxious readiness which produced physical damage. The connection was being made that if stress contributed to things like heart disease and cancer, maybe by reducing stress one might help prevent these illnesses. This gave tremendous energy to the new field of stress reduction.
George Solomon was a psychiatrist at Stanford who in the 1960s showed that by destroying a rat’s hypothalamus, the animal suffered a marked decline in immune function.
Ten years later, Ader at the University of Rochester, demonstrated that the cells of the immune system (long thought to be under automated control) could be conditioned in the same way that Pavlov’s dogs responded to a bell by salivating. His colleague Felton demonstrated direct connections between the fibers of the sympathetic nervous system and the organs and cells of the immune system. Candace Pert and Soloman Snyder at Hopkins suggested that there were “peptide messengers” between the cells of the brain and those of the immune system. They called this new field of looking at connections between psychological processes and the nervous and immune systems psychoneuroimmunology.
I guess the answer to this question depends on what you mean by the word “prove”. If your question is about whether or not we can prove a connection between stress, depression, or anxiety and the development of cancer, that gets a bit trickier. The progression of research noted above would certainly suggest that this is an area for investigation.
A psychologist by the name of Bahnson reviewed the literature on stress, emotions, and cancer in 1980. At that time he felt that there was evidence to demonstrate an association between what he called a “particular configuration” and the development of cancer. That “configuration” was characterized by denial and depression, absence or loss of affection in early childhood, severe loss later in life, and strong and persistent feelings of hopelessness and helplessness. Bahnson based this conclusion on several studies, one being a prospective study of medical students at Hopkins which revealed a correlation between lack of closeness to parents and later development of cancer. The second was an observation that women with suspicious cervical biopsies who had recently suffered a loss were more likely to develop cervical cancer. The third study found that patients who had cancer were significantly more likely than controls to have suffered loss of an important relationship and to have an inability to express hostile feelings.
In the 28 years since this review, studies on personality and cancer have confirmed some of these findings but not all. A recent meta-analysis from the UK showed that stress-related psychological factors are associated with a higher incidence of cancer. There is some association between personality/stress and the development of cancer, and certainly other factors such as genetics, environment, and diet play a significant role.
What impact does stress have after the diagnosis of cancer? Do our patients’ thoughts, feelings, beliefs, and attitudes affect their outcomes? If so, how can we affect positive change?
One measure of the emotional state of a patient is to assess quality of life. Patti Ganz and Allen Coates showed that patients with lung or breast cancer who are more optimistic, more involved in their usual activities, and more hopeful about the future have an improved survival over those who are less optimistic or engaged. This is a finding that is independent of other prognostic factors. In the same meta-analysis from the UK that I just mentioned, Chida found that a stress-prone personality or unfavorable coping styles and negative emotional responses were related to higher cancer incidence and poorer survival. Another review article from JCO a couple of yearsago, showed there was a correlation between patient reported outcomes (such as quality of life measures) and survival. In her conclusion Dr. Gotay called for “studies that go beyond documenting this phenomenon and test hypotheses about why patient reported outcomes may be linked to survival…” And she goes on to conclude that interventions that improve patient reported outcomes have the potential to increase survival.