Frequency of Silent Brain Metastasis Before Prophylactic Cranial Irradiation in Small Cell Lung Cancer

Prophylactic cranial irradiation (PCI) decreases incidence of brain metastasis and improves survival in patients with limited disease-small cell lung cancer (LD-SCLC) who achieved complete response (CR) after treatment. There is no satisfactory evidence about the necessity of new brain imaging for asymptomatic metastasis immediately prior to PCI. The present study aimed to evaluate the frequency of brain metastasis in SCLC patients without neurological symptoms who are candidates for PCI.

The data files of 243 patients with SCLC referred for cranial irradiation were retrospectively reviewed. The patients with following characteristics were enrolled to the study; 1) LD-SCLC patients with CR after chemoradiotherapy who are candidates for PCI. 2) No neurological signs or symptoms of brain metastasis after chemoradiotherapy. 3) Having brain imaging at initial diagnosis and before PCI.

Ninety-nine patients (83 male, 83.3%) were included in this study. Median age was 60 years. Time interval between initial and reevaluation for brain metastasis was median 5.5 months (range; 4.7-7.1). Asymptomatic brain metastasis rate was 20.2% (18/99).

Even if local disease is under control, asymptomatic brain metastasis is not rare. Therefore, patients who are candidates for PCI after completion of chemoradiotherapy should be reimaged for brain metastasis before PCI.