title: Vitamin D3 from sunlight may improve the prognosis of breast-, colon- and prostate cancer (Norway).
abstract: OBJECTIVE
  To investigate whether prognosis of breast-, colon- and prostate cancer may be related to vitamin D(3), induced from solar ultra-violet (UV) radiation, through studies on geographical and seasonal variations in UV radiation.
  
  
  METHODS
  This study includes 115,096 cases of breast-, colon- or prostate cancer, diagnosed between 1964 and 1992. Among these, 45,667 deaths due to the cancer were registered. On the basis of a north-south gradient in solar UV radiation and geographical climatic differences, Norway was divided into eight residential regions. According to seasonal variations in UV radiation, four periods of diagnosis during the year were used. Case fatality according to residential region and to season of diagnosis was estimated using Cox regression. The effects of occupational sun exposure, childbearing pattern and educational level were also evaluated.
  
  
  RESULTS
  No geographic variation in case fatality was observed for the three cancer types studied. A significant variation in prognosis by season of diagnosis was observed. Diagnoses during summer and fall, the seasons with the highest level of vitamin D(3), revealed the lowest risk of cancer death.
  
  
  CONCLUSIONS
  The results suggest that a high level of vitamin D(3) at the time of diagnosis, and thus, during cancer treatment, may improve prognosis of the three cancer types studied.
authors.affiliation: The Cancer Registry of Norway, Institute of Population-based Cancer Research, Montebello, 0310 Oslo, Norway. trude.eid.robsahm@kreftregisteret.no
authors.forename: Trude Eid
authors.initials: TE
authors.lastname: Robsahm
authors.forename: Steinar
authors.initials: S
authors.lastname: Tretli
authors.forename: Arne
authors.initials: A
authors.lastname: Dahlback
authors.forename: Johan
authors.initials: J
authors.lastname: Moan
mesh_terms: D001943:Breast Neoplasms / Q000401:mortality* / Q000517:prevention & control; D002762:Cholecalciferol / Q000096:biosynthesis* / Q000502:physiology; D003110:Colonic Neoplasms / Q000401:mortality* / Q000517:prevention & control; D004522:Educational Status; D005260:Female; D006801:Humans; D008297:Male; D009664:Norway / Q000453:epidemiology; D016273:Occupational Exposure; D011379:Prognosis; D011471:Prostatic Neoplasms / Q000401:mortality* / Q000517:prevention & control; D012307:Risk Factors; D012621:Seasons; D013472:Sunlight; D016896:Treatment Outcome
chemical_list: D002762:Cholecalciferol