Examination of factors associated with lymph node metastases in lung carcinoids: Results from a single institution retrospective cohort study.

Background: Well-differentiated lung neuroendocrine tumors (NETs), also known as typical and atypical carcinoids, have a decreased incidence of lymph node (LN) and distant metastases compared to poorly differentiated lung NETs. We aimed to (i) examine the clinicopathologic features associated with LN involvement in lung carcinoids and (ii) describe the postoperative management of patients with LN metastases.

Methods: We identified 98 patients who underwent surgical resection and lymph node sampling at Stanford University. We assessed the following and used AJCC staging version 7: clinical features (age, sex, race, prior malignancy, smoking history), tumor features (functional syndrome, histology, size, location, laterality), pre-operative workup performed (imaging and suspicion of LN metastases), surgery (nodes and stations sampled, margin status, surgical approach, and type of surgery), and recurrence outcome. These features were examined between patients with and without LN metastases using the Wilcoxon test (continuous variables) and Fisher's exact test (categorical variables).

Results: 87 patients (89%) had typical carcinoid and 11 patients (11%) had atypical carcinoid. 17 patients were found to have at least one positive lymph node, with 11 having N1 disease and 6 having N2 disease. In the univariable analysis, patients with lymph node disease were more likely to have recurrence of lung carcinoid (29% vs. 6%, p=0.01). In the multivariable logistic regression, there was a trend towards performance of preoperative SSTR imaging and lymph node involvement (OR = 3.06, p=0.07). No patients received adjuvant therapy.

Conclusion: We found a trend for the performance of SSTR imaging and association of lymph node metastases in both univariable and multivariable analysis. A large proportion (41%) of patients with lymph node positive disease had < 2 cm tumors. This suggests the potential importance of incorporating SSTR imaging into routine practice and not restricting the use of this staging modality in patients with small tumors.