Psychological Factors in Oncology
Many health professionals and lay people believe that psycho-logical factors play a major role in cancer onset and progression. The media have promoted popular ideas of overcoming cancer through “mind over body”. Enthusiasm for these optimistic theo-ries and practices should be tempered by the recognition that sci-entific evidence clarifying the relationship between psychological factors and cancer lags far behind. Nevertheless, there is an excit-ing frontier of exploration of immune and endocrine mechanisms that may provide a pathophysiological basis for some PFAMC in cancer. In this section, aspects of PFAMC in oncology that have received support in the research literature are reviewed.
The most active area of study has been the linking of affective states, particularly depression (as a symptom or as a disorder), with the onset and course of cancer. A meta-analysis of studies relating depression to later cancer development found a small statistically significant but clinically insignificant association (McGee et al., 1994). The interpretation of epidemiologic studies is complex with many methodological problems.
Besides epidemiologic studies, other research has focused on the impact of affective states on outcome in cancer patients. Emotional distress may predict lower survival with lung cancer as may anger in metastatic melanoma patients. Other studies have found positive, negative, or mixed associations between depres-sion and mortality in cancer patients. Besides survival, depres-sion in cancer patients may result in poorer pain control, poorer compliance and less desire for life-sustaining therapy. Neither cancer onset nor progression have been clearly shown to be influ-enced by bereavement.
A large body of literature has described cancer patients’ degree of emotional expressiveness and its purported effect on progno-sis. Epidemiological studies, however, have not supported a rela-tionship between emotional suppression and cancer occurrence or mortality.
An enormous literature documents the adverse effects of mal-adaptive health behaviors as risk factors for the development of various cancers, especially smoking but also excessive alcohol use, unsafe sex and dietary practices. Relatively less research has examined the effects of interpersonal variables on cancer, but there is some evidence that the quality of relationships may affect cancer onset and its course. Social relations and social sup-port and their effects on cancer patients (as with other diseases) are complex phenomena and may vary with cancer site and extent of disease.
A number of human studies have shown an increased fre-quency of stressful life events preceding the onset of cervical, pancreatic, gastric, lung, colorectal and breast cancer. Many other studies have failed to find any association between preceding stressful life events and cancer onset, relapse, or progression.
A number of studies have shown improvement in the quality of life in cancer patients receiving group therapy including improved mood and vigor, decreased pain and better. The possibility that cancer patients receiving psychotherapy might have increased survival time as well as improved quality of life has generated intense study with more evidence showing improvement in pain control and mood than for increased survival.