PERSONALITY-FACTORS AND BREAST-CANCER DEVELOPMENT - A PROSPECTIVE LONGITUDINAL-STUDY

Background: It has been estimated that approximately 25% of all breast cancers in women can be explained by currently recognized somatic her editary and physiologic) risk factors, It has also been hypothesized t hat psychological factors may play a role in the development of breast cancer. Purpose: We investigated the extent to which personality fact ors, in addition to somatic risk factors, may be associated with the d evelopment of primary breast cancer, Methods: We employed a prospectiv e, longitudinal study design, From 1989 through 1990, a personality qu estionnaire was sent to all female residents of the Dutch city of Nijm egen who were 43 years of age or older, This questionnaire was sent as part of an invitation to participate in a population-based breast can cer screening program, Women who developed breast cancer among those w ho returned completed questionnaires were compared with women without such a diagnosis in regard to somatic risk factors and personality tra its, including anxiety, anger, depression, rationality, anti-emotional ity (i.e., an absence of emotional behavior or a lack of trust in one' s own feelings), understanding, optimism, social support, and the expr ession and control of emotions. Conditional logistic regression analys is was used to identify variables that could best explain group member ship (i.e., belonging to the case [breast cancer] or the control [with out disease] group), Results: Personality questionnaires were sent to 28 940 women, and 9705 (34%) were returned in such a way that they cou ld be used for statistical analyses, Among the 9705 women who returned useable questionnaires, 131 were diagnosed with breast cancer during the period from 1989 through 1994. Seven hundred seventy-one age-match ed control subjects (up to six per case patient) were selected for the analyses, Three variables were found to be statistically significantl y associated with an increased risk of breast cancer: 1) having a firs t-degree family member with breast cancer (versus not having an affect ed first-degree relative, odds ratio [OR] = 4.05; 95% confidence inter val [CI] = 1.76-9.31); 2) nulliparity (i.e., having no children) (vers us having had a child before the age of 30 years, OR = 2.67; 95% CI = 1.26-5.68); and 3) a relatively high score on the personality scale of anti-emotionality (versus a low score, OR = 1.19; 95% CI = 1.05-1.35) . Conclusions and Implications: With the exception of a weak associati on between a high score on the anti-emotionality scale and the develop ment of breast cancer, no support was found for the hypothesis that pe rsonality traits can differentiate between groups of women with and wi thout breast cancer. We recommend that this study be continued and tha t other studies be encouraged to explore possible relationships betwee n personality factors and the risk of breast cancer.