Brain Metastases in Lung Cancer: Associations with Primary Tumor Location and Histological Subtype

Shweta Mohata; H.S. Kumar; Neeti Sharma

doi:10.31557/RRO.2026.12.1.85

Authors

Shweta Mohata Associate Professor, Department of Radiation Oncology, ATRCTRI, Sardar Patel Medical College, Bikaner, Pakistan.
H.S. Kumar Associate Professor, Department of Radiation Oncology, ATRCTRI, Sardar Patel Medical College, Bikaner, Pakistan.
Neeti Sharma Associate Professor, Department of Radiation Oncology, ATRCTRI, Sardar Patel Medical College, Bikaner, Pakistan.

DOI:

https://doi.org/10.31557/RRO.2026.12.1.85

Abstract

Introduction: Brain metastases (BM) are a common complication of lung cancer. Although histological subtype is associated with BM risk, the relationship between primary tumor location within the lung and BM remains unclear. This study evaluated the association of primary tumor location and histological subtype with the occurrence and distribution of BM.

Materials and Methods: This retrospective cohort study included 496 patients with primary lung cancer diagnosed between January 2021 and December 2023. Patients with a previous primary malignancy were excluded. Demographic, clinical, pathological, and radiological data were retrospectively collected. BM was confirmed by contrast-enhanced magnetic resonance imaging. Patients were classified according to BM status at diagnosis or during treatment and follow-up. Associations between BM, primary tumor location, and histological subtype were assessed.

Results: Among 496 patients, 468 (94.35%) had non-small cell lung cancer (NSCLC) and 28 (5.65%) had small cell lung cancer (SCLC). BM occurred in 97 patients (19.56%), including 87 (18.59%) with NSCLC and 10 (35.71%) with SCLC. Among patients with BM, 64 (65.98%) had left-sided, 25 (25.77%) right-sided, and 8 (8.25%) bilateral primary tumors. BM was more frequent in SCLC than NSCLC and, among NSCLC subtypes, in adenocarcinoma than squamous cell carcinoma (20.56% vs. 12.39%). Multiple intracranial lesions were present in 85.57% of patients with BM. The most frequently affected sites were the right parietal lobe, cerebellum, and frontal lobes.

Conclusion: BM was more frequent in SCLC than NSCLC and occurred more commonly in adenocarcinoma than squamous cell carcinoma. A predominance of left-sided primary tumors was observed among patients with BM, particularly those with NSCLC. However, the independent effect of primary tumor location remains uncertain and requires confirmation in larger prospective studies using multivariable analyses.