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

Abstract

OBJECTIVES: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. MATERIAL AND METHODS: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. RESULTS: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). CONCLUSION: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. KEYWORDS: Prophylaxis, brain, imaging, SCLC, metastasis INTRODUCTIONApproximately 30% of patients with small cell lung cancer (SCLC) initially staged as limited disease (LD) are candidates for combined model treatment (CMT) with curative intent. CMT with sequential or concurrent chemoradiotherapy (CRT) achieves complete response (CR) in 50%-60% of patients. However, the blood-brain barrier precludes the penetration of chemotherapeutic agents to the brain. The risk for brain metastasis occurrence is approximately 50% in the first 2 years after diagnosis [1]. Silent brain metastasis may develop at some point during the treatment course even in patients with a CR of intrathoracic disease. Emerging evidence suggests that prophylactic cranial irradiation (PCI) in patients with LD-SCLC who have achieved CR after CRT reduces the incidence of brain metastasis and improves survival [2,3]. However, the recommended dose for whole brain radiotherapy in patients with brain metastasis differs from the preferred dose for PCI [2].Lung cancer guidelines recommend routine initial evaluations for brain metastasis with contrast-enhanced (CE) magnetic resonance imaging (MRI) or computed tomography (CT) in patients with SCLC [4,5]. The necessity of radiological reevaluation to detect asymptomatic brain metastasis before PCI has not been remarked on the guidelines, contrary to recommendations for the initial staging of SCLC.Manapov et al. [6] detected silent brain metastasis in 32.5% of small patients size with LD-SCLC who were complete responders to CRT with pre-PCI second CE-MRI. However, there is a paucity of data on the frequency of asympt...

Construction of Brain Metastasis Prediction Model and Optimization of Prophylactic Cranial Irradiation Selection for Limited-Stage Small-Cell Lung Cancer

“…Although previous studies have explored the risk factors of BM in SCLC, there are some deficiencies [20,[32][33][34][35][36][37][38][39][40][41]. First, brain MRI was not used as a standard measure and was only performed with symptoms.…”

“…First, brain MRI was not used as a standard measure and was only performed with symptoms. For this reason, some patients with brain metastasis were included in these studies, resulting in the inability to accurately evaluate the related factors of brain metastasis [32,[35][36][37][38][39][40]. Second, some studies have taken PCI as a factor related to brain metastasis.…”

Radiation therapy in the prevention and management of brain metastases in patients with small cell lung cancer: a narrative review

“…The study also found a reduction in BM with a HR 0.45 (95% CI: 0.38-0.55) in favour of PCI though there was significant heterogeneity in brain imaging following chemo-radiation (7). Restaging magnetic resonance imaging (MRI) brain following completion of chemo-radiation should be considered given that interval BM occur in 20-32% of patients (8,9). However, even following a negative restaging brain MRI, BM subsequently occur in 37-41% of patients without PCI (10,11).…”

GOECP/SEOR radiotherapy guidelines for small-cell lung cancer

“…Prior to initiating PCI after completion of CRT, a brain MRI should be performed for re-evaluation. In patients with chest CR, MRI performed after CRT shows an incidence of BM ranging from 20%-32%[ 137 , 138 ].…”