Hypercalcemia of Malignancy and Colorectal Cancer

Area of Science:

• Oncology
• Endocrinology
• Medical Research

Background:

• Colorectal cancer (CRC) can rarely present with humoral hypercalcemia of malignancy (HHM).
• HHM is often caused by parathyroid hormone-related peptide (PTHrP) secretion, but other mechanisms like calcitriol production can contribute.
• Understanding the association between CRC and HHM is crucial for timely diagnosis and management.

Observation:

• A case of anal squamous cell carcinoma with liver metastases presented with severe hypercalcemia, elevated PTHrP, and 1,25-dihydroxyvitamin D.
• The patient's hypercalcemia was refractory to bisphosphonates and prednisone but improved with chemotherapy.
• A literature review identified 29 cases of CRC-associated PTHrP-mediated hypercalcemia.

Findings:

• CRC-associated HHM predominantly affects middle-aged men with advanced metastatic disease, particularly liver metastases.
• Patients typically present with severe hypercalcemia (mean 15.6 mg/dL).
• This condition carries a high mortality rate (79%) with a median survival of only 54.5 days.

Implications:

• HHM, especially PTHrP-mediated, should be considered in metastatic CRC patients with hypercalcemia.
• Clinicians must be aware of potential combined etiologies for refractory hypercalcemia.
• Effective management of hypercalcemia hinges on treating the underlying colorectal cancer.