DOTATATE-PET has Low Sensitivity in Preoperative Nodal Staging of Carcinoid Tumors of the Lung

L. L. Tsai¹, S. Bommakanti², S. Sridharan², N. Myall², B. Guenthart³, D. Liou⁴, N. Lui⁵, L. Backhus⁶, M. Berry⁵, J. Shrager⁴, I. Elliott^7
1Stanford, Menlo Park, California ²Stanford, Palo Alto, California ³Stanford Health Care, San Jose, California ⁴Stanford University School of Medicine, Stanford, California ⁵Stanford University, Stanford, California ⁶Stanford University, Dept. of Cardiothoracic Surgery, Stanford, California ⁷Stanford, Stanford, California

Purpose: DOTATATE-PET scans use a radiotracer that binds to somatostatin-2 receptors (SSTR2) on neuroendocrine cells to stage neuroendocrine tumors. While the accuracy of FDG-PET in staging other lung cancer histologies is well-documented,1,2 the accuracy of DOTATATE-PET in nodal staging of pulmonary carcinoids is unknown.

Methods: We reviewed all patients with lung carcinoids who underwent DOTATATE-PET prior to surgical resection at a single institution between July 2017 and November 2023. Patients were excluded if the primary tumor was not avid on DOTATATE-PET or if no pathologic lymph node assessment was performed. Using surgical pathology reports as the gold standard, we assessed concordance of the preoperative clinical stage based on DOTATATE-PET and postoperative pathologic stage. Sensitivity, specificity, negative predictive value and positive predictive value were calculated. Chi square analysis was used for categorical variable comparisons and two sample t tests were used for continuous variable comparisons.

Results: A total of 57 patients underwent resection of lung carcinoid tumors and 6 patients were excluded, 3 for no uptake in primary tumor and 3 for no lymph nodes examined. This resulted in a total of 51 patients for analysis - 41 typical carcinoids and 10 atypical carcinoids. Table 1 shows clinical characteristics, stratified by whether the preoperative DOTATATE-PET was found to be accurate or inaccurate compared to the surgical pathology report in terms of nodal status. None of the characteristics examined were significantly associated with DOTATATE-PET accuracy. Overall, 13 patients (25.5%) were found to have nodal involvement on pathologic evaluation, but the DOTATATE-PET was positive in only 3 of these patients. In the 38 patients who were pathologic node negative, the DOTATATE-PET was also negative in 36 patients. Overall, there were 36 true negatives, 3 true positives, 10 false negatives, and 2 false positives, resulting in a sensitivity of 23%, specificity of 94.7%, and a NPV of 78.2% and PPV of 60%. The accuracy of DOTATATE-PET for preoperative nodal staging of lung carcinoids was 76.5%.

Conclusion: DOTATATE-PET has low sensitivity (23%) for detection of nodal involvement in lung carcinoids. Thorough node evaluation during resection is necessary regardless of DOTATATE-PET results. The utility of a DOTATATE-PET is likely limited to evaluation of distant metastatic disease. Knowledge of the limitations of this test is critical for thoracic surgeons.

Identify the source of the funding for this research project: None