title: Seasonal variations in breast cancer diagnosis in Osaka, Japan.
abstract: To date, seasonal variations in breast cancer diagnosis have been reported in Western countries. In the present study, we calculated the number of breast cancer diagnoses according to season between 1976 and 2005, using data from the Osaka Cancer Registry. In all time periods and all age groups, breast cancer diagnosis showed peaks in early summer and troughs in winter. The number of breast cancer diagnoses in the spring, summer, autumn, and winter were 2,595(26%), 2,739(27%), 2,585(26%), and 2,120(21%)in 1976-1985; 4,219(26%), 4,581(28%), 4,2 62(26%), and 3,466(21%)in 1986-1995; and 6,299(25%), 6,852(28%), 6,368(26%), and 5,335(22%)in 1996-2005, respectively. Most cases were diagnosed because of an awareness of a breast mass. The trend in screening-detected cases differed from the overall trend. As screening becomes more widely adopted, these seasonal variations might change. Careful monitoring is needed to confirm these findings.
authors.affiliation: Division of Surgery, Saiseikai Senri Hospital.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Toyoda
authors.forename: Tomio
authors.initials: T
authors.lastname: Nakayama
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Hojo
authors.forename: Setsuko
authors.initials: S
authors.lastname: Yoshioka
authors.forename: Yoshiichi
authors.initials: Y
authors.lastname: Maeura
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000175:diagnosis*; D055088:Early Detection of Cancer; D005260:Female; D006801:Humans; D007564:Japan; D008875:Middle Aged; D012621:Seasons; D013997:Time Factors