PTH and neoplasm: 3 The evidence for tumor-induced hypercalcemia is insufficient: Preoperative and postoperative serum PTHrP levels were not measured, and hypercalcemia was only inferred to be caused by tumor-secreted PTHrP based on indirect evidence, including changes in serum calcium levels, negative bone metastasis on positron emission tomography-computed tomography (PET-CT), and normal serum parathyroid hormone (PTH) levels.