Parathyroid Hormone-related Peptide Is a Better Indicator of Cancer Treatment Efficacy Than Serum Calcium.
Jerome H Check
✦ AI-curated · Sources linked
Case in brief
A 66-year-old woman with extensive cutaneous squamous cell carcinoma of the scalp, unsuitable for primary surgical removal, received cemiplimab. She was hospitalized with severe hypercalcemia while awaiting treatment approval. After the second course, serum calcium had fallen to the low-normal range, but PTHrP had risen markedly. Imaging subsequently demonstrated rapid progression with bone, brain, lung, and liver metastases, and she died shortly thereafter.
What made this case unusual
Serum calcium appeared to improve during treatment while PTHrP rose markedly; subsequent imaging showed rapid metastatic progression.
Diagnostic / clinical pearl
In PTHrP-mediated hypercalcemia, a falling or normalized serum calcium may not reflect cancer control. Serial PTHrP measurement may provide additional information about treatment efficacy.