The prevalence of primary hyperparathyroidism (PHPT) in patients with prostate cancer has not been investigated. We consecutively enrolled 69 men (aged 51-87) with histologically confirmed prostate cancer (31 were candidate to radical prostatectomy, radiotherapy or hormone therapy, HT; 7 were in active surveillance and 31 already had radical prostatectomy while on HT). Eight patients had skeletal metastases. After clinical evaluation, we measured serum PSA (total and ratio), chromogranin A, S-100, ionised calcium, parathyroid hormone, 25(OH)D, bone alkaline phosphatase, collagen type I C-terminal cross-linked telopeptide, intact and C terminal fibroblast growth factor (FGF) 23. The protocol was approved by the Sapienza University of Rome Ethics Committee. We found a high prevalence of PHPT among cancer patients (n=9, 13%). We stratified the population on the basis of Gleason Score (GS) [≤7(3+4) and ≥7(4+3)], PSA (<4 ng/ml, between 4 and 10, and >10) and HT (yes/no) and used a generalised linear model with a logit link to predict the probability of developing PHPT. The model showed that only GS, C-terminal FGF-23 and HT had a significant effect (p<0.05). After controlling for other variables, we observed that the rise in FGF-23 increases the odds of developing PHPT by 2% (p<0.02), and higher values of GS are associated with a higher probability of developing PHPT (log-odds=3.6, p <0.01). Conversely, higher GS in association with HT play a significant protective role (p<0.01), decreasing the odds of developing PHPT by 8%. The prospective investigation shows a remarkable prevalence of PHPT in men with prostate cancer. The multivariate analysis demonstrates that more aggressive prostate cancer, as determined by GS, is a significant predictor of increased risk of PHPT, suggesting a possible causative relationship rather than a simple association between the two disorders. A thorough biochemical evaluation of mineral metabolism parameters is therefore mandatory in patients with prostate cancer.
Disclosure: The authors declared no competing interests.