The incidence of symptomatic brain metastases from extra-pulmonary small cell carcinoma: Is there a role for prophylactic cranial irradiation in a clinically relevant population cohort?

Abstract Background and purpose To examine the incidence and outcomes of patients with brain metastases from extra-pulmonary small cell carcinoma (EPSCC) and assess the indication for prophylactic cranial irradiation (PCI). Materials and methods A Provincial cancer registry was used to conduct a retrospective, population-based study of patients diagnosed with EPSCC between January 1997 and December 2011. The primary end point was the incidence of brain metastases. The secondary endpoint was overall survival. A "PCI Eligible" cohort was defined to provide an estimation of the incidence of brain metastases in clinically relevant patients. Results In 287 patients, the primary sites were 21% gastrointestinal, 34% genito-urinary, 14% gynecologic, 5% head/neck and 25% unknown primary. Thirty-five (12.5%) patients had brain metastases: 12 (4.2%) at initial diagnosis and 23 (8%) later in the disease course. In PCI Eligible patients, the 3-year cumulative incidence of new brain metastases was 5.5% for M0 stage disease and 26.3% for M1 disease. There was no significant difference in the incidence of brain metastases between primary sites. Conclusions The incidence of brain metastases in patients with EPSCC is comparatively low, even in a cohort of patients that were suitable for PCI. Based on our analysis, we cannot recommend PCI for patients with EPSCC.