title: The influence of personality and perceived stress on the development of breast cancer: 20-year follow-up of 29,098 Japanese women.
abstract: Breast cancer is the most common cancer in women. However, it remains unproven whether psychological factors have an influence on breast cancer incidence. In our earlier study, subjects possessing two personality traits, decisiveness and "ikigai" (a Japanese word meaning something that makes one's life worth living), showed a significantly lower risk of developing breast cancer, although no psychological factors have been convincingly demonstrated to have an influence on breast cancer development in other studies. Therefore, we conducted this follow-up analysis to confirm the association between breast cancer incidence and psychological traits, using the final dataset of a large-scale prospective cohort study in Japan. We identified 209 cases of incident breast cancer out of a maximum 21-year follow-up of 29,098 Japanese women. Cox proportional hazard regression analysis, adjusted for the same potential confounders used in our previous study, did not reveal any significant relationships between breast cancer incidence and four psychological traits: having "ikigai", decisiveness, ease of anger arousal, and perceived stress. Our finding is consistent with previous studies, and suggests that the psychological traits are unlikely to be an important risk factor for breast cancer.
authors: Clinical Study Support, Inc, Nagoya, 460-0003, Japan.|Department of Public Health, Aichi Medical University School of Medicine, Nagakute, 480-1195, Japan.
authors: Takayuki
authors: T
authors: Sawada
authors: Department of Public Health, Aichi Medical University School of Medicine, Nagakute, 480-1195, Japan.
authors: Takeshi
authors: T
authors: Nishiyama
authors: Clinical Study Support, Inc, Nagoya, 460-0003, Japan.|Department of Public Health, Aichi Medical University School of Medicine, Nagakute, 480-1195, Japan.
authors: Norimasa
authors: N
authors: Kikuchi
authors: Department of Public Health, Aichi Medical University School of Medicine, Nagakute, 480-1195, Japan.
authors: Chaochen
authors: C
authors: Wang
authors: Department of Public Health, Aichi Medical University School of Medicine, Nagakute, 480-1195, Japan.
authors: Yingsong
authors: Y
authors: Lin
authors: Department of Public Health, Sapporo Medical University School of Medicine, Sapporo, 060-8556, Japan.
authors: Mitsuru
authors: M
authors: Mori
authors: Department of Hygiene and Preventive Medicine, Iwate Medical University School of Medicine, Morioka, 028-3694, Japan.
authors: Kozo
authors: K
authors: Tanno
authors: Department of Public Health, Hokkaido University Graduate School of Medicine, Sapporo, 060-8638, Japan.
authors: Akiko
authors: A
authors: Tamakoshi
authors: Department of Public Health, Aichi Medical University School of Medicine, Nagakute, 480-1195, Japan.
authors: Shogo
authors: S
authors: Kikuchi
mesh_terms: D044466:Asian People; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000523:psychology*; D016001:Confidence Intervals; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008875:Middle Aged; D010551:Personality; D016016:Proportional Hazards Models; D018709:Statistics, Nonparametric; D013315:Stress, Psychological / Q000453:epidemiology*