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Hypercalcemia Is of Uncertain Significance in Patients With Advanced Adenocarcinoma of the Prostate

Hypercalcemia in the setting of prostate cancer is rare with an uncertain pathophysiology and more research is needed into the role of parathyroid hormone-related peptide as a growth factor and possibly target-directed monoclonal antibody therapies.
Federal Practitioner. 2020 July;37(7)a:320-324
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A computed tomography (CT) scan of the chest and abdomen was taken due to the patient’s heavy smoking history, an incidentally detected right lung base nodule on chest X-ray, and hypercalcemia. The CT scan showed multiple right middle lobe lung nodules with and without calcifications and calcified right hilar lymph nodes (Figure 1).

To evaluate the pancytopenia, a bone marrow biopsy was done, which showed that 80 to 90% of the marrow space was replaced by fibrosis and metastatic malignancy. Trilinear hematopoiesis was not seen (Figure 2). The tumor cells were positive for prostate- specific membrane antigen (PSMA) and negative for cytokeratin 7 and 20 (CK7 and CK20).4 The former is a membrane protein expressed on prostate tissues, including cancer; the latter is a form of protein used to identify adenocarcinoma of unknown primary origin (CK7 usually found in primary/ metastatic lung adenocarcinoma and CK20 usually in primary and some metastatic diseases of colon adenocarcinoma).5 A prostatic specific antigen (PSA) test was markedly elevated: 335.94 ng/mL (1.46 ng/mL on a previous 2011 test).

Metastatic adenocarcinoma of the prostate was diagnosed without a prostate biopsy. To determine the extent of bone metastases, a technetium-99m-methylene diphosphonate (MDP) bone scintigraphy demonstrated a superscan with intense foci of increased radiotracer uptake involving the bilateral shoulders, sternoclavicular joints, and sternum with heterogeneous uptake involving bilateral anterior and posterior ribs; cervical, thoracic, and lumbar spines; sacrum, pelvis, and bilateral hips, including the femoral head/neck and intertrochanteric regions. Also noted were several foci of radiotracer uptake involving the mandible and bilateral skull in the region of the temporomandibular joints (Figure 3).

The patient was initially treated with IV isotonic saline, followed by calcitonin and then pamidronate after kidney function improved. His calcium level responded to the therapy, and a plan was made by medical oncology to start androgen deprivation therapy (ADT) prior to discharge.

He was initially treated with bicalutamide, while a luteinizing hormone-releasing hormone agonist (leuprolide) was added 1 week later. Bicalutamide was then discontinued and a combined androgen blockade consisting of leuprolide, ketoconazole, and hydrocortisone was started. This therapy resulted in remission, and PSA declined to 1.73 ng/ mL 3 months later. At that time the patient enrolled in a clinical trial with leuprolide and bicalutamide combined therapy. About 6 months after his diagnosis, patient’s cancer progressed and became hormone refractory disease. At that time, bicalutamide was discontinued, and his therapy was switched to combined leuprolide and enzalutamide. After 6 months of therapy with enzalutamide, the patient’s cancer progressed again. He was later treated with docetaxel chemotherapy but died 16 months after diagnosis.

showed improvement of hypercalcemia at the time of discharge, but 9 months later and toward the time of expiration, our patient developed secondary hyperparathyroidism, with calcium maintained in the normal range, while iPTH was significantly elevated, a finding likely explained by a decline in kidney function and a fall in glomerular filtration rate (Table).