Primary salivary gland-type lung cancer: Imaging and clinical predictors of outcome

OBJECTIVE. The objective of our study was to assess whether CT features and FDG uptake of primary salivary gland-type tumors of the lung are associated with tumor type, disease stage, or survival. MATERIALS AND METHODS. CT (n = 30) and PET (n = 15) data of 30 consecutive patients with primary salivary gland-type tumors of the lung were retrospectively evaluated for tumor size, location, and homogeneity and the presence of lymphadenopathy, pleural effusions, and metastases. Maximum FDG uptake and volumetric FDG uptake of the tumors were recorded. The Wilcoxon rank sum and Fisher exact tests and univariate Cox regression were used for statistical calculations. RESULTS. Compared with mucoepidermoid carcinomas, adenoid cystic carcinomas (57%) were larger (mean, 3.5 vs 2.2 cm, respectively; p = 0.03), more frequently involved the central airways (94% vs 63%; p = 0.002), and had a higher median FDG uptake (p = 0.0264). Higher FDG uptake of the primary tumor was associated with nodal tumor involvement (p = 0.05). The median overall survival times for patients with adenoid cystic carcinoma and mucoepidermoid carcinoma were 7.7 and 4.0 years, respectively. Imaging features that significantly affected overall survival included the presence of mediastinal or hilar lymphadenopathy (hazard ratio [HR], 4.33; 95% CI, 1.15-16.26; p = 0.03), suspected metastatic disease (HR, 5.10; 95% CI, 1.27-20.47; p = 0.02), and primary tumor heterogeneity (HR, 3.46; 95% CI, 1.04-11.55; p = 0.04). CONCLUSION. Higher FDG uptake is associated with nodal disease in patients with primary salivary gland-type tumors of the lung but is not predictive of survival, whereas CT features suggestive of advanced disease correlate with worse outcome.