Incidence of Brain Metastasis at the Initial Diagnosis of Lung Squamous Cell Carcinoma on the Basis of Stage, Excluding Brain Metastasis

IntroductionCurrent National Comprehensive Cancer Network guidelines recommend routine brain magnetic resonance imaging (MRI) screening in patients with stage II to IV non-small cell carcinoma, regardless of histological subtype. This recommendation might not be universally applicable, however, because brain metastasis (BM) is seen less frequently in patients with lung squamous cell carcinoma (SCC) than in those with a histological diagnosis of nonsquamous cell carcinoma.MethodsThe cases of 564 patients with lung SCC in our institution between January 2012 and December 2013 were reviewed prospectively for comprehensive staging. All subjects' lung SCC, but not their BM, was staged on the basis of the seventh edition of the guidelines of the American Joint Committee on Cancer. We evaluated the incidence of BM across the stages and clinical factors associated with BM.ResultsOf the 564 patients, 28 (5.0%) had BM. BM did not occur in patients with stage Ia or Ib disease; however, it increased significantly as the disease progressed from stage IIa to IV (p < 0.001, trend test). Multivariate analysis showed that tumor involvement in N3 lymph nodes and distant metastasis other than BM (M1b) was independently associated with the development of BM.ConclusionsRoutine brain MRI screening in patients with lung SCC in stage II to IV can help to evaluate asymptomatic BM. By contrast, we did not find any evidence supporting routine brain MRI screening in patients with stage I disease.