Palliative radiotherapy is effective for both well- and poorly differentiated neuroendocrine neoplasms

Introduction: The outcomes of palliative radiation therapy (RT) for neuroendocrine neoplasms (NEN) are seldom reported. We investigated outcomes following palliative radiotherapy in a cohort of patients with NENs. We hypothesised that well-differentiated NEN will be less likely to have a clinical response than poorly differentiated NEN.Methods: Patients who received at least one course of palliative RT were identified using the New Zealand NETwork! Registry. Patients with Merkel cell carcinoma, pulmonary small cell carcinoma or asymptomatic patients were excluded. Clinical response to RT within 90 days and overall survival were analysed alongside clinical variables (fractionation, RT site, tumour differentiation and tumour primary site).Results: The cohort comprised 79 patients, with 147 courses of palliative RT delivered. Clinical response was measurable for 100 courses, with clinical response rate of 76%. A course delivered to a well-differentiated NEN was associated with 2.02-fold (95% CI 0.67, 6.12; P = 0.21) increase in odds of a clinical response compared to a poorly differentiated NEN. Median overall survival from the first fraction of RT was 94 days (95% CI 80, 138 days). Overall survival was higher in well-differentiated NEN than in poorly differentiated NEN (HR 0.2, 95% CI 0.10-0.40, P-value < 0.001); 30-day mortality was 7%. There were significantly reduced odds of clinical response for non-bone sites, and for courses >10 fractions compared to a single fraction.Conclusion: Palliative RT is an appropriate option for management of symptoms in patients with both well- and poorly differentiated metastatic NEN.