Need for measurement of bone mineral density in patients of prostate cancer before and after orchidectomy: role of quantitative computer tomography.

BACKGROUND Androgen deprivation therapy is the first-line systemic treatment of prostate cancer, orchidectomy remaining the most common mode in view of cost-effectiveness and better compliance. Accelerated bone loss is common after orchidectomy, which exacerbates osteoporosis already common in this patient-population. We studied the need of periodic measurement of bone mineral density after orchidectomy. MATERIAL AND METHODS Fifty five patients of adenocarcinoma prostate opting for orchidectomy were prospectively studied. Follow up ranged from 6 to 18 months. Lumbar spinal (L1-L3) trabecular bone mineral density (BMD) was measured with quantitative computed tomography (QCT) at baseline and every 6 months after orchidectomy, and compared with preoperative values. RESULTS Mean (+/- SD) age of the patients was 69.9 +/- 7.9 years and BMD 115.7 +/- 35.7 mg/cm2 with T-score -1.89 +/- 1.26 and Z-score 0.30 +/- 1.30. Thirty three percent patients were osteoporotic at baseline, as defined by a T-score <-- 2.5. Fall of BMD six months after orchidectomy was statistically significant (12.1%, p = 0.0001) increasing the proportion of osteoporotics to 49%. Twenty four patients completing 12 months follow up, were separately analyzed and showed similar fall in BMD in first 6 months of follow up (13%) and further 8% loss in next six months. Ten patients were followed up for 18 months, and these did not show significant loss of BMD beyond 12 months (p = 0.9). CONCLUSIONS Osteoporosis is common in hormone-naive population affected by prostate cancer and orchidectomy leads to accelerated exacerbation of this bone loss. Periodic measurement of BMD using QCT after ADT would help in early detection of osteoporosis.