Severe hypercalcaemia in metastatic prostate cancer with biallelic BRCA2 mutations and lytic bone lesions

Molecular genetics is increasingly used to define the course and prognosis of prostate cancer. Hypercalcaemia of malignancy is a rare complication of metastatic prostate cancer associated with poor outcomes. However, no associations have yet been made in literature between pathogenic genetic mutations and hypercalcaemia in patients with prostatic malignancy.We report of a patient with bone-metastatic prostate cancer. He received sequential genetic tests for pathogenic mutations. A somatic BRCA2 truncation mutation was identified at diagnosis and suppressed on olaparib. Six months after stopping olaparib, several pathogenic mutations, including biallelic BRCA2 mutations, were identified. The patient developed large lytic bone lesions and a severe symptomatic hypercalcaemia. He was hospitalised and treated aggressively for hypercalcaemia but died shortly thereafter. To our knowledge, this is the first case of hypercalcaemia in metastatic prostate cancer to be contextualised within complex genetic mutations.