In a fit man with stage IV prostate cancer and spinal metastases who has undergone bilateral orchidectomy, is chemotherapy and radiation therapy indicated?

Management of Stage IV Prostate Cancer with Spinal Metastases Post-Orchidectomy

Yes, this patient absolutely requires both chemotherapy and radiation therapy in addition to the androgen deprivation already achieved through bilateral orchidectomy. 1

Immediate Urgent Priority: Rule Out Spinal Cord Compression

• Obtain an urgent MRI of the spine immediately before initiating any systemic therapy, as back pain with known vertebral metastases indicates potential spinal cord compression, which occurs in approximately 95% of patients with metastatic spinal cord compression 1, 2
• If spinal cord compression is confirmed, start dexamethasone immediately and arrange urgent radiation oncology consultation for hypofractionated radiotherapy 1
• Patients with hormone-resistant prostate cancer who develop persistent back pain should undergo imaging studies (bone scan, spine CT-scan or MRI) and prophylactic local radiotherapy to the spine if bony metastases are identified 2

Systemic Chemotherapy: Mandatory for Fit Patients

Docetaxel 75 mg/m² every 3 weeks for 6 cycles is required for this fit patient with metastatic hormone-naïve prostate cancer, as this combination with androgen deprivation improves survival compared to androgen deprivation alone 1, 3

• The bilateral orchidectomy has already achieved surgical castration, which must be maintained throughout treatment 3
• Docetaxel using a 3-weekly schedule should be considered for symptomatic, castration-refractory disease and provides both survival benefit and symptom palliation 3, 4
• For patients aged ≥65 years, provide growth-factor support during docetaxel therapy 5

Radiation Therapy: Essential for Spinal Metastases

Palliative external beam radiotherapy is indicated for painful bone metastases, with a single 8 Gy fraction providing equivalent pain relief to multi-fraction schedules while being more convenient and cost-effective 1, 4, 3

• Radiotherapy provides back pain relief in 50-58% of cases, with 30-35% achieving complete pain resolution 1
• For metastatic spinal cord compression specifically, high-dose fractionated radiotherapy (20 Gy in 5 fractions) or a short course (8 Gy in 2 fractions) is indicated 4
• External beam radiotherapy should be offered for patients with painful bone metastases from castration-refractory disease (1 × 8 Gy has equal pain-reducing efficacy to multifraction schedules) 3

Mandatory Bone-Protective Therapy

All patients with bone metastases must receive bone-protective agents to prevent skeletal-related events (pathologic fractures, spinal cord compression, surgery or radiation to bone) 1, 3, 4

• Denosumab 120 mg subcutaneously every 4 weeks is superior to zoledronic acid in delaying skeletal-related events (HR 0.82, P=0.0002) 1
• Alternatively, zoledronic acid 4 mg intravenously every 3-4 weeks reduces skeletal-related events and is recommended in stage IV bone metastatic disease 3, 4
• Preventive dental screening is mandatory before initiating bone-protective therapy to prevent osteonecrosis of the jaw, and ensure adequate calcium and vitamin D supplementation during treatment 1

Comprehensive Monitoring Requirements

Implement comprehensive surveillance from treatment initiation including: 1

• MRI spine surveillance for all patients with vertebral metastases
• Bone densitometry monitoring for osteoporosis
• Screen for metabolic syndrome complications and cardiovascular risk factors
• PSA and testosterone monitoring every 3 months 6
• Regular exercise is strongly recommended to reduce fatigue and improve quality of life 1

Pain Management Strategy

Concurrent analgesic therapy with NSAIDs and opioids should be used alongside radiotherapy for optimal pain control 1

• Radiotherapy provides pain relief but should not be the sole pain management strategy
• Low-dose corticosteroids (prednisone or dexamethasone) can provide additional benefit in castration-resistant disease 3

Future Treatment Upon Progression

When disease progresses to castration-resistant prostate cancer, first-line treatment options include: 1, 4

• For asymptomatic/mildly symptomatic CRPC: abiraterone or enzalutamide
• For symptomatic CRPC: docetaxel 75 mg/m² every 3 weeks remains standard chemotherapy
• Continue androgen suppression indefinitely throughout all subsequent treatments 3, 4

Critical Pitfall to Avoid

Do not delay systemic chemotherapy while waiting for radiotherapy planning – these treatments should be coordinated but chemotherapy initiation should not be postponed, as the survival benefit of combined ADT plus docetaxel is time-sensitive 1