Purpose: Prostate cancer is the most common tumor in men. To the best of our knowledge a systematic assessment of bone and mineral abnormalities has not been performed in prostatic cancer patients consecutively enrolled.
Methods: This study was therefore carried out to investigate changes of skeletal and mineral metabolism in patients with prostate cancer (n = 69). A population of patients with cancer of various origin was also investigated as a control group (n = 53), since a comparison with non-prostate cancer patients has not been previously reported.
Results: In the prostatic cancer group, one patient had extremely high values of C-terminal Fibroblast Growth Factor 23, low values of tubular reabsorption of phosphate and very high values of bone alkaline phosphatase, suggesting the diagnosis of oncogenic osteomalacia. We found nine patients with primary hyperparathyroidism in the group of prostate cancer vs. only one in cancer patients group (p < 0.026). We stratified the population on the basis of Gleason score, prostate specific antigen and hormonal therapy. Using a generalized linear model with a logit link to predict the probability of developing primary hyperparathyroidism, only Gleason score, C-terminal fibroblast growth factor 23 and hormonal therapy had a significant effect (p < 0.05). Controlling for other covariates, a rise in fibroblast growth factor 23 increases the odds of developing primary hyperparathyroidism by 2% (p = 0.017), while patients with higher values of Gleason score have a much greater probability of developing primary hyperparathyroidism (log-odds = 3.6, p < 0.01). The probability decreases with higher values of Gleason score while on hormonal therapy; a further decrease was observed in patients on hormonal treatment and lower values of GS. Finally, lower grade of Gleason score without hormonal therapy have a significant protective factor (p < 0.01) decreasing the odds of developing primary hyperparathyroidism by 8%.
Conclusion: We showed a remarkable prevalence of primary hyperparathyroidism in men with prostate cancer; the multivariate analysis demonstrates that higher aggressiveness of prostate cancer, as determined by Gleason score, is a significant predictor of increased risk of developing primary hyperparathyroidism.
Keywords: FGF23; Hypercalcemia; Hyperparathyroidism; Prostate cancer; Vitamin D.