Background: To determine whether the distribution, staging features, or tumor histology of non-small cell lung cancer (NSCLC) distinguishes neurologically symptomatic from asymptomatic patients initially diagnosed with lung cancer, and to determine whether these factors may predict the presence of brain metastasis. Methods: We performed a retrospective review of 809 patients with NSCLC and brain metastases who were treated in our institution between January 1996 and March 2003. Patients who had brain metastasis on initial staging were included. Thoracic computed tomographic scans were reviewed for lung tumor features and staging. Neurological computed tomographic or magnetic resonance image scans were assessed for distribution of brain metastases. Medical records were reviewed for comprehensive staging, tumor histology, and neurological symptoms. Fisher's exact test was used to determine any differences among tumor histology, staging, and imaging features among patients with or without neurological symptoms. Results: Of the 809 patients, 181 had brain metastasis at initial staging. Among these 181 patients, 120 (66%) presented with neurological symptoms (group 1); 61 (34%) patients were asymptomatic (group 2). Patients with adenocarcinoma and large-cell carcinoma had greater odds of brain metastases than patients with squamous cell carcinoma (p ϭ 0.001). There were 106 (58.6%) patients with adenocarcinoma, 32 (17.7%) with large cell carcinoma, and 18 (9.9%) with squamous cell carcinoma. In both groups, most lung cancers were in the right lung with upper lobe dominance. No significant difference in tumor histology or T stage was found between groups, although group 2 was more likely to have a higher N stage. Of the 181 patients with brain metastasis, 60 (33.1%) had N0 disease, 51 (28.2%) had T1 disease, and 23 (19.2%) had no other metastasis. There was no correlation between number/distribution of brain metastases and tumor histology, although patients with disease in the cerebellum or temporal lobes had a greater likelihood of neurological symptoms (odds ratio 3.7). Conclusion:There was no significant difference in tumor histology, staging, or distribution between symptomatic or asymptomatic patients with NSCLC with brain metastases. The odds of brain metastases were greater in those with adenocarcinoma or large-cell carcinoma.

Abstract. We determined if specific tumor types of nonsmall cell lung cancer can be identified by variance in FDG-PET standard uptake value (SUV) in combination with characteristics on CT. Staging FDG-PET and CT scans of 81 patients (34 men and 47 women, average age 67±11 years) with 82 lung cancers were analyzed. Mean tumor SUV was calculated at the location of maximum FDG uptake. Tumor size, margins, and location were analyzed on CT. Statistical analysis compared SUV between tumor subtypes, assessed relationship between tumor subtype and features on CT and determined if combination of CT and SUV patterns predicted tumor type. In total 35 adenocarcinomas (AC); 15 bronchioloalveolar cell carcinomas (BAC), 23 squamous cell carcinomas and 9 large cell carcinomas were evaluated. Significant differences were found between SUV of all AC and squamous cell (p<0.0001); between all AC and large cell (p=0.03); between non-BAC AC and squamous cell types (p=0.0005); BAC and non-BAC AC (p=0.04), BAC and squamous cell (p<0.0001); BAC and large cell (p=0.004). Ground glass was the most significant CT feature in distinguishing tumor types, which was seen in BAC (p<0.0003). In conclusion, SUVs for non-small cell lung cancer were most significantly different between BAC and all other NCLC cell subtypes. The presence of ground glass in a nodule on CT is a significant feature for BAC and should raise the suspicion for this tumor type despite low FDG uptake.

The detection of small pulmonary nodules by breathing CTAC and FDG-PET is relatively poor. Therefore an additional diagnostic thoracic CT scan obtained during suspended inspiration is recommended for thorough evaluation of those patients in whom detection of pulmonary metastases is necessary for management.

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