Bone Flare After Initiation of Novel Hormonal Therapy in Patients with Metastatic Hormone-sensitive Prostate Cancer: A Case Report

Background: The 2020 European Association of Urology prostate cancer guidelines recommend androgen deprivation therapy (ADT) in combination with apalutamide and enzalutamide, a new generation of androgen receptor antagonists, as first-line therapy. A decrease in prostate-specific antigen (PSA) levels may occur in the early stages of novel hormonal therapy; however, radionuclide bone imaging may suggest disease progression. During follow-up, PSA, radionuclide bone imaging, and prostate-specific membrane antigen (PSMA) positron emission tomography - computed tomography (PET-CT) are needed for systematic evaluation.

Case Summary: We admitted a 56-year-old male patient with metastatic hormone-sensitive prostate cancer. Initial radionuclide bone imaging, magnetic resonance imaging (MRI), and PSMA PET-CT showed prostate cancer with multiple bone metastases. Ultrasound-guided needle biopsy of the prostate revealed a poorly differentiated adenocarcinoma of the prostate with a Gleason score: 5+4 = 9. The final diagnosis was a prostate adenocarcinoma (TNM). ADT with novel hormonal therapy (goseraline sustained-release implant 3.6 mg monthly and apalutamide 240 mg daily) was commenced. Three months later, radionuclide bone imaging and MRI revealed advanced bone metastasis. However, PSMA PET-CT examination showed a significant reduction in PSMA aggregation on the bone, indicating improved bone metastases. Considering that progressive decrease in the presenting lumbar pain, treatment strategies were considered to be effective.

Conclusion: ADT using novel hormonal therapy is effective for treating patients with prostate adenocarcinoma. Careful evaluation must precede treatment plan changes.