Primary Salivary Gland–Type Lung Cancer: Imaging and Clinical Predictors of Outcome

Abstract

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.

Primary Adenoid Cystic Carcinoma of the Peripheral Lungs

“…Okereke et al reported that the SUV exhibits a strong correlation with survival and that a higher SUVmax predicts a poor survival outcome in patients with NSCLC [13]. Elnayal et al showed that FDG uptake was much higher in ACC (SUVmax : median, 8.6; range, 3.7 -17.6) than in other salivary gland-type tumors of the lung, although increased FDG uptake didnʼt translate into worse overall survival or progression-free survival time [14]. However, the SUVmax of the ACC in their report was much higher than in our case.…”

Tracheobronchial tumors

“…These tumors characteristically grow intraluminally in the central airway, tend to occur in non-smokers and younger patients and have a much better prognosis than the more common types of lung cancer (adenocarcinoma and SCC). The most common histologic type is ACC, comprising about two thirds of the cases, whereas MEC comprises about a third and only a few EMEC primary salivary gland-type tumors of the lung have been described in the literature (20,38,39). ACC ACC is the most common salivary-type tumor of large airways and the second common primary tracheal tumor with a prevalence of 0.04-0.2% (19).…”

“…The largest imaging studies reported that FDG uptake in primary salivary gland-type tumors of the lung is variable, depending on the grade of differentiation; like in other indolent tumors (39,43). Timely diagnosis of ACC is important because prognosis is improved with early treatment (21,22).…”

“…Punctate calcifications within the tumor are seen in half of the patients. Metastases to the regional lymph node are rare, and the prognosis is excellent (13,39,48). Reported series showed variable amounts and patterns of FDG uptake …”

Malignancies of the Pediatric Lower Respiratory Tract

“…In a recent SEER survey [ 43 ], all 14 patients survived. In a recent Egyptian study of radiographic features [ 44 ], overall survival of patients with salivary gland-type tumors of the lung was affected by the presence of mediastinal/hilar lymphadenopathy, suspected metastatic disease, and primary tumor heterogeneity. Higher FDG uptake on PET was associated with nodal metastasis.…”