Personality and Cancer
The following entry describes the influence of personality on cancer development and prognosis.
For decades, the possible influence of personality dynamics on cancer formation, progression, and eventual outcome has been hotly debated. Many of those who believe personality type and dynamics influence cancer development maintain that the two factors not only covary but that a causal relationship exists. In other words, some research scientists maintain that not only is cancer more prevalent among certain personality types but that unfavorable personality dynamics may actually lead to the development of some forms of cancer. Early advocates contested that various personality features, types, traits, and disorder can impact this relationship. However, over time there has been a considerable amount of disagreement about the strength of these effects in that preliminary research findings have been replicated inconsistently across samples and/or across cultures.
Beginning in the early 1960s, a psychologist named Hans Eysenck began to stir considerable controversy when he posited that personality’s role in cancer development was undeniable. In a study concerning the role of personality in male lung cancer patients, Eysenck found that lung cancer patients have personality features distinct from the cigarette smoking population, non-cancer patients, and patients with cancer in other areas of the body (Kissen and Eysenck 1962). Specifically, Eysenck reported that based on personality inventory scores, those scoring low in neuroticism, and in some cases high on extraversion, had approximated a sixfold chance of developing lung cancer than those who scored highly on neuroticism (Eysenck 1985). Eysenck went on to establish the position that there exists a cancer-prone personality, called Type C, exhibited by specific personality traits such as overt cooperation, emotional suppression of anger and hostility, patience, passivity, acceptance, and lack of assertiveness. He stated that individuals with these personality traits are at greater risk for cancer development and have shorter life spans. There also exists an additive risk based on immunosuppression due to elevated cortisol levels resulting from excessive stress (Eysenck 1994).
These findings have been replicated by other researchers in various populations. Research by Coppen and Metcalfe (1963) found similar findings to those done by Kissen and Eysenck in a breast cancer population. In a study by Hagnell (1966), using the Sjöbring personality scales, which are closely related to the major personality dimensions recognized by Eysenck, cancer development in women seemed to be significantly correlated with high extraversion scores. Morris et al. (1981) again found that low neuroticism scores were present in cancer patients. Additionally, a study by Berndt et al. (1980) replicated the earlier findings of low neuroticism scores being present in a breast cancer population with no significant differences in extraversion.
Other studies have established consistent findings and additionally found links between hopelessness and helplessness and hostility and anger. Regarding hopelessness and helplessness, recurrence-free survival was significantly less common than among patients who had initially reacted to cancer by denial or who had a fighting spirit (Greer et al. 1979). In terms of hostility and anger, short-term cancer survivors who died less than 1 year from baseline revealed significantly lower levels of hostility and anger, with higher levels of positive mood (Derogatis et al. 1979). Research supporting the idea that personality contributes to cancer development also did so by using different personality tools including the Maudsley Personality Inventory (Berndt et al. 1980), the Multiphasic Minnesota Personality Inventory (MMPI) (Blumberg et al. 1954), the Cattell 16 PF (Butler et al. 1982), the Eysenck Personality Questionnaire (Eysenck 1975), and more. This was also replicated across samples and cultures in latter-day Yugoslavia (Grossarth-Maticek et al. 1985), in two studies in Germany (Van der Ploeg 1991), and in both large and small patient populations. In some cases, such as the one found by Horne and Picard (1979), psychosocial factors and personality were 1–2 times as important to cancer development as was smoking. Interestingly enough, patient populations both undergoing and not receiving chemotherapy had increased survival lengths when engaged in psychotherapy (Grossarth-Maticek et al. 1983a,b), consistent with Eysenck’s (1994) findings that psychological therapy can help people suffering from inoperable cancer to live longer than controls. These discoveries imply that personality, on its own, could ostensibly contribute to cancer development, prognosis, and mortality.
More contemporary research regarding the role of personality in cancer risk has proven less consistent, and evidence remains inconclusive. Some question the validity of earlier assertions that personality covaries with cancer, and even more doubts have been raised about a causal relationship. The skepticism has mostly been attributed to perceived flaws in previous research designs, in particular the failure to control for other important causal factors. Other scientists purport that personality most certainly has a relationship with cancer prognosis but that risk factors go far beyond what was previously studied in terms of extraversion and neuroticism.
In a study published by Nakaya et al. (2005), 41,442 Japanese residents completed the Eysenck Personality Questionnaire-Revised, and cancer patients were identified among them. Of these cases, no significant associations were identified between personality traits and risk of death. When examining neuroticism and extraversion specifically, Nakaya et al. (2010) also found no significant associations in Swedish and Finnish populations concerning personality traits as direct risk factors for cancer or survival. Similarly, Jokela et al. (2014) discovered no significant associations between personality traits and increased risk of cancer-related mortality in a study of over 2000 cancer cases using the five-factor model of personality, a widely used and much more contemporary instrument of personality assessment.
In relation to the cancer trajectory, a study by Dahl (2010) suggested that most studies to date do not lend much support to personality being a causative factor for cancer and that although there are some associations between personality traits and cancer survival (lower optimism and higher neuroticism both being associated with shorter survival), there are other factors to consider. More mental distress, poorer quality of life, the presence of post-traumatic stress disorder, and lifestyle choices can also be potential risk factors. Thus, high neuroticism is important in understanding the clinical management of cancer patients, but the problem is multifaceted, and one trait alone cannot necessarily be attributed to causing cancer or cancer-related death.
There also appears to be a lack of consistency in terms of the types of traits that predict the effect of personality on mortality. In a study by Schoormans et al. (2017), elements of distressed personality (Type D), which refers to the combined traits of social inhibition and negative affectivity along with lower quality of life, and not Type C personality, were predictive of an increased risk of mortality due to any and all causes, with negative affectivity specifically demonstrating the greatest amount of influence in an older male population. Denollet (1998) further supported this argument, demonstrating that Type D men who had been diagnosed with coronary heart disease were more likely to develop some forms of cancer.
Research by Denollet (1999) suggests that the link between personality and cancer is inconsistent, yet worthy of ongoing investigation. Personality-related variables can influence disease progression and development, quality of life, and future risk by influencing health-enhancing or health-inhibiting behaviors, depression, adaptation, and emotional distress, and that state and trait measures should be considered in psycho-oncological research. Krok-Schoen and Baker (2016) further gave strength to this argument stating that not only do personality traits, such as neuroticism, influence the experience of pain severity but that there are also reported differences across genders. Specifically, higher neuroticism was associated with lower reported pain severity in women suggesting that neuroticism may be a protective factor for women regarding pain severity.
Given that there exists much inconsistency in the literature regarding the impact of personality on the development and progression of cancer, much more research must be conducted and replicated cross-sectionally to understand this relationship.
The exact role of personality when considering cancer development, prognosis, treatment, and outcome appears to remain unknown. Arguments made in favor of or in opposition to this relationship are currently inconsistent, and more research is needed to assess this relationship further.
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