Serum 25-Hydroxy Vitamin D Levels in Bulgarian Patients with Prostate Cancer: a Pilot Study

Background: The antiproliferative effect of the active form of vitamin D on cancer cells and its ability to induce cell differentiation and suppression of tumor-induced angiogenesis in the last decade has provoked enormous research for the elucidation of its role in the prevention of different types of cancer and in slowing down the malignancy progression. The aim of the present pilot study was to determine the circulating 25-hydroxy vitamin D (25OHD) levels in Bulgarian prostate cancer (PCa) patients and to investigate their relationship with various determinants associated with the severity and progression of the disease. Methods: A total of 53 male patients (mean age 67.0 +/- 7.1 years) with clinical suspicion for PCa were enrolled in the study. All patients were subjected to systemic transrectal ultrasound-guided tru-cut prostate biopsies (10 cores at least). Detected tumors were graded using the Gleason grading system. Prostate specific antigen (PSA) serum levels were measured immunochemically. The 25OHD assay was performed by a validated HPLC-UV method. Other covariates (BMI, age, family history of PCa) were collected by interview at the time of hospitalization. One-way ANOVA with Kruskal Wallis statistics was used for comparison of medians of different parameters. The level of significance was set at p < 0.05. Results: Significantly lower 25OHD levels were detected in PCa patients compared to those with benign prostate hyperplasia (BPH) (p < 0.05). Patients with high grade tumors (Gleason score >= 7) showed significantly lower 25OHD levels, while those with low grade tumors (Gleason score < 7) revealed better 25OHD status (50.49 vs. 63.17 nmol/L, p < 0.05). A moderate negative correlation between 25OHD levels and the Gleason score was established (Spearman r = -0.46, p < 0.05). Significant seasonal variations in 25OHD levels, both for PCa and BPH patients, were detected (p < 0.01). Conclusions: This preliminary study shows an association between 25OHD status and classical markers characterizing the severity of PCa. The results might suggest a potential beneficial role of vitamin D for PCa patients. Further prospective studies are needed to strengthen the interrelationships between 25OHD levels and variables related with PCa and to test them for causality.