Clustering of personality traits in youth and the subsequent development of cancer among physicians.

Using 14 personality measures obtained while the subjects were in medical school, the resulting profiles of 972 physicians were clustered into five groups using a two-stage cluster analysis procedure. Subjects were followed over a 30-year period to determine the cumulative survival rate (proportion of subjects remaining free of cancer) in each group. Statistically significant group differences in survival rate were found, with the group characterized by acting out and emotional expression having the most favorable curve (less than 1% developing cancer). The group characterized as "loners," who may well have suppressed their emotions, had the most unfavorable survival curve and was 16 times more likely to develop cancer than was the group characterized by acting out and emotional expression.