Ultraviolet sunlight, personality, and cancer incidence: A nomothetic American state-level analysis

This is the first research to examine the relation of ultraviolet (UV) sunlight and personality to cancer incidence employing the same database. Two nomothetic studies focused on 2000–2010 and employed the 50 American states as analytical units. Both used state UV levels determined from National Weather Service data, state cancer incidence data from the Centers for Disease Control and Prevention, and state Big Five personality scores based on the responses of 619,397 state residents to an online survey published by Rentfrow and his colleagues in 2008. Both studies controlled for state socioeconomic status, urbanization, and a composite of four common cancer risk factors. Both used multiple regression strategies. Study 1 found that state UV levels related negatively to total invasive cancer incidence but showed equivocal results in relation to White skin cancer incidence. State resident neuroticism scores were positively related to total invasive cancer incidence but unrelated to White skin cancer incidence, which was associated with high agreeableness and low extraversion. Study 2 used the state incidence of 25 leading cancers as separate criteria. UV levels independently predicted the state incidence of 12 cancer types, while neuroticism independently predicted the incidence of 10 types. As well, 32 interactions were found between UV levels and personality regarding the incidence of 19 cancer types. For nine independent interactions found with the maximum number of statistical controls—five involving neuroticism, three agreeableness, and one conscientiousness—personality differences in cancer incidence were quite pronounced under low UV conditions but negligible under high UV conditions.