Mechanisms, Management and Prognosis of Paraneoplastic Hypercalcemia in Penile Squamous Cell Carcinoma: A Structured Review

Background and Objectives: Paraneoplastic hypercalcemia represents a rare but clinically significant complication of penile squamous cell carcinoma (PSCC); however, limited information is available for this condition. Therefore, this systematically conducted narrative review aimed to comprehensively evaluate the pathophysiological mechanisms, clinical presentation, therapeutic strategies and prognostic outcomes of tumor-induced hypercalcemia in PSCC. Methods: A comprehensive literature search was conducted across PubMed/MEDLINE and Scopus databases from their inception to December 2024. Cases were included if they documented histopathologically confirmed PSCC with biochemically verified hypercalcemia and objective evidence of paraneoplastic etiology. Data extraction included tumor characteristics, severity of hypercalcemia, mechanistic classification, therapeutic interventions and survival outcomes. The search methodology followed PRISMA 2020 guidelines adapted for narrative synthesis. Given the absence of comparative studies for this rare condition, all study types were eligible for inclusion, resulting in an evidence base that consisted exclusively of case reports and case series. Results: Twelve published cases spanning six decades (1965–2024) met the inclusion criteria. The median age at presentation was 56 years, with 91.6% of patients presenting with advanced disease. Severe hypercalcemia (≥14 mg/dL) occurred in 66.7% of cases, with a median calcium level of 15.45 mg/dL. Two established pathophysiological mechanisms were identified: PTHrP-mediated humoral hypercalcemia and bone metastasis-associated hypercalcemia. By contrast, three cases with unmeasured PTHrP levels had an undetermined mechanism. Despite biochemical correction, median overall survival was 9 weeks following diagnosis of hypercalcemia. Conclusions: Paraneoplastic hypercalcemia in PSCC represents a rare metabolic emergency. While aggressive management can achieve biochemical correction, the occurrence of hypercalcemia uniformly indicates advanced tumor biology with limited survival benefit. Early recognition and prompt multidisciplinary intervention remain essential for symptomatic relief and preserving quality of life. Reporting future cases and collaborating with international registries will be necessary to improve understanding of this rare paraneoplastic entity.