title: Prostate cancer survival is dependent on season of diagnosis.
abstract: BACKGROUND
  We have earlier found that the prognosis for several cancers is dependent on season of diagnosis. More recently, both prostate cancer incidence and mortality have been shown to increase with increasing latitude, which probably relates to photosynthesis of vitamin D.
  
  
  METHODS
  The 3 year survival of prostate cancer patients has been analyzed with the Cox regression method for two age groups at different latitudes in Norway.
  
  
  RESULTS
  Patients diagnosed during the summer and autumn had the best prognosis (Ralative risk (RR) death 0.8; 95% CI 0.75-0.85). Similar results were observed in three regions of the country that differ with respect to annual fluences of solar UV radiation, incidence rates of squamous cell carcinoma (SCC) and intake of fish. Furthermore, similar relationship between the season and survival was seen among patients </=65 years and >65 years old, although the younger group had a slightly larger advantage of summer and autumn diagnosis.
  
  
  CONCLUSIONS
  The seasonal effect on prognosis may be related to the seasonal variations of calcidiol (the marker of vitamin D status). The lack of latitude effect and the similarity of prognosis for different age groups may be related to higher consumption of vitamin D in food in the north region and to increase of such consumption with age.
authors.affiliation: Department of Radiation Biology, Institute for Cancer Research, Montebello, Oslo, Norway. zoya.lagunova@medisin.uio.no
authors.forename: Zoya
authors.initials: Z
authors.lastname: Lagunova
authors.forename: Alina Carmen
authors.initials: AC
authors.lastname: Porojnicu
authors.forename: Arne
authors.initials: A
authors.lastname: Dahlback
authors.forename: Jens Petter
authors.initials: JP
authors.lastname: Berg
authors.forename: Tomasz M
authors.initials: TM
authors.lastname: Beer
authors.forename: Johan
authors.initials: J
authors.lastname: Moan
mesh_terms: D000368:Aged; D000818:Animals; D002112:Calcifediol / Q000097:blood; D002294:Carcinoma, Squamous Cell / Q000097:blood / Q000453:epidemiology* / Q000473:pathology; D004032:Diet; D005399:Fishes; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D011471:Prostatic Neoplasms / Q000097:blood / Q000453:epidemiology* / Q000473:pathology; D012621:Seasons; D013472:Sunlight; D016019:Survival Analysis
chemical_list: D002112:Calcifediol