Vitamin D Metabolites in Nonmetastatic High-Risk Prostate Cancer Patients with and without Zoledronic Acid Treatment after Prostatectomy

SIMPLE SUMMARY: Recent research on prostate cancer and vitamin D is controversial. We measured three vitamin D(3) metabolites in 32 selected prostate cancer patients after surgery at four time points over four years. Within a large European study, half of the patients were prophylactically treated with zoledronic acid (ZA); the others received a placebo. After the study start, all the patients daily took calcium and vitamin D(3). The development of metastasis was not affected by ZA treatment. While two vitamin D metabolites had higher values after the study’s start, with constant follow-up values, the 1,25(OH)(2)-vitamin D(3) concentrations remained unchanged. The latter form was the only metabolite that was higher in the patients with metastasis as compared to those without bone metastasis. This result is surprising. However, it is too premature to discuss possible prognostic value yet. Our results should be confirmed in larger cohorts. ABSTRACT: There are limited and discrepant data on prostate cancer (PCa) and vitamin D. We investigated changes in three vitamin D(3) metabolites in PCa patients after prostatectomy with zoledronic acid (ZA) treatment regarding their metastasis statuses over four years. In 32 patients from the ZEUS trial, 25(OH)D(3), 24,25(OH)(2)D(3), and 1,25(OH)(2)D(3) were measured with liquid chromatography coupled with tandem mass spectrometry at four time points. All the patients received daily calcium and vitamin D(3). Bone metastases were detected in 7 of the 17 ZA-treated patients and in 5 of the 15 controls (without ZA), without differences between the groups (p = 0.725). While 25(OH)D(3) and 24,25(OH)(2)D(3) increased significantly after the study’s start, with following constant values, the 1,25(OH)(2)D(3) concentrations remained unchanged. ZA treatment did not change the levels of the three metabolites. 25(OH)D(3) and 24,25(OH)(2)D(3) were not associated with the development of bone metastases. In contrast, 1,25(OH)(2)D(3) was also higher in patients with bone metastasis before the study’s start. Thus, in high-risk PCa patients after prostatectomy, 25(OH)D(3), 24,25(OH)(2)D(3), and 1,25(OH)(2)D(3) were not affected by supportive ZA treatment or by the development of metastasis over four years, with the exception of 1,25(OH)(2)D(3), which was constantly higher in metastatic patients. There might be potential prognostic value if the results can be confirmed.