Supplementary Material for: Carboplatin in Combination with Oral or Intravenous Etoposide for Extra-Pulmonary, Poorly-Differentiated Neuroendocrine Carcinomas

Background: Carboplatin-etoposide (CarboEtop) is a 1st-line option for patients with advanced extra-pulmonary (EP), poorly-differentiated (PD) neuroendocrine carcinoma (NEC). Different schedules are used in clinical practice and randomised evidence is lacking. Objectives: To provide real-life outcomes of carboplatin combined with oral or intravenous (IV) etoposide (Etop) in advanced EP-PD-NEC, from 2 specialist centres. Methods: Activity/efficacy/toxicity data of CarboEtop were collected retrospectively and analysed. Results: We identified 113 patients; median age: 65.8 years; male: 64%; gastro-entero-pancreatic origin: 54%; stage IV: 90%; median Ki-67: 70%; median follow-up: 11.5 months. A total of 123 courses of CarboEtop (oral: 45%; IV: 55%) were administered; 106 (86%) 1st-line, 16 (13%) 2nd-line, and 1 (1%) 3rd-line. Disease control rate: 74.5% in 1st-line and 69.2% in 2nd/3rd-line, with no significant difference between oral and IV Etop in 1st-line (69.8 vs. 80.8%, p = 0.237). Median progression-free survival (PFS): 6.0 and 4.5 months in 1st-line and 2nd/3rd-line, respectively. Overall survival (OS): 11.5 and 12.5 months in 1st-line and 2nd/3rd-line, respectively. The schedule (oral versus IV Etop) did not impact on 1st-line PFS (5.6 vs. 6.2 months, p = 0.179), although there was a trend towards shorter OS (8.9 vs. 12.1 months, p = 0.069). Liver metastases correlated with worse 1st-line PFS (p = 0.015) and 1st-line OS (p < 0.001) on multivariable analysis. The commonest grade 3–4 adverse event was myelosuppression (49%), with comparable toxicity between oral and IV Etop, except for venous thromboembolism (12.5 vs. 1.7%, p = 0.04). Conclusions: CarboEtop for advanced EP-PD-NEC is active, effective, and well-tolerated. Oral and IV Etop schedules are associated with comparable toxicity; activity should be compared in larger cohorts.