Serum vitamin D (25OHD3) levels and the risk of different subtypes of breast cancer: A nested case-control study.
BACKGROUND
Previous studies regarding the association between serum 25-hydroxyvitamin D (25OHD3) and breast cancer risk have not been conclusive. The aim of this study was to investigate the potential association between pre-diagnostic serum 25OHD3 levels and the risk of different subtypes of breast cancer.


METHODS
The study was based on The Malmö Diet and Cancer Study recruiting 17,035 women from 1991 to 1996. A total of 764 incident breast cancers with matched controls were analysed for 25OHD3 in samples collected at baseline, before diagnosis. A logistic regression analysis was used to calculate odds ratios with 95% confidence intervals for tertiles of 25OHD3 in relation to different subtypes of breast cancer, i.e. defined according to tumour type, tumour size, lymph node involvement, histological grade, oestrogen receptor (ER) status, progesterone receptor (PgR) status, Ki67, cyclin D1 and p27.


RESULTS
As compared to the 1st tertile of 25OHD3, the second tertile had a statistically significantly lower risk of ER negative tumours, PgR negative tumours and tumours with a high expression of Ki67, A similar pattern was seen in relation to large tumours (≥21 mm), grade III tumours, and tumours with low p27 expression, but these associations did not reach statistical significance. The third tertile had a similar risk as the first tertile.


CONCLUSIONS
We found that women with low levels of 25OHD3, as compare to women in the middle tertile, had a high risk of breast tumours with an unfavourable prognosis.
Department of Clinical Research Malmö, Surgery, Lund University, Malmö, Sweden; Department of Surgery, University of Gothenburg, Sahlgrenska University Hospital/Östra, Gothenburg, Sweden. Electronic address: leila.shirazi@vgregion.se.
L
L
Shirazi
Department of Surgery, Skåne University Hospital, Lund University, Lund, Sweden.
M
M
Almquist
Division of Oncology and Pathology, Department of Clinical Sciences, Lund, Lund University, Sweden.
S
S
Borgquist
Department of Transitional Medicine, Section for Clinical Chemistry, Lund University, Malmö, Sweden.
J
J
Malm
Department of Clinical Research Malmö, Surgery, Lund University, Malmö, Sweden; Department of Plastic Surgery, Skåne University Hospital, Lund University, Malmö, Sweden.
J
J
Manjer
D001943:Breast Neoplasms / Q000097:blood / Q000737:chemistry* / Q000473:pathology*; D002112:Calcifediol / Q000097:blood*; D016022:Case-Control Studies; D019938:Cyclin D1 / Q000032:analysis; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000032:analysis; D005260:Female; D006801:Humans; D019394:Ki-67 Antigen / Q000032:analysis; D008207:Lymphatic Metastasis; D008875:Middle Aged; D060787:Neoplasm Grading; D011960:Receptors, Estrogen / Q000032:analysis; D011980:Receptors, Progesterone / Q000032:analysis; D012307:Risk Factors; D047368:Tumor Burden
D019394:Ki-67 Antigen; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D019938:Cyclin D1; D050760:Cyclin-Dependent Kinase Inhibitor p27; D002112:Calcifediol
Breast cancer; Ki67; Oestrogen receptor status; Progesterone receptor status; Tumour size; Vitamin D