Objective  To investigate the clinical characteristics and prognosis of patients with locally advanced or metastatic pulmonary neuroendocrine tumors (NETs).

Methods The clinical records of patients with locally advanced or metastatic pulmonary NETs in Peking University Cancer Hospital & Institute were selected from January 2014 to June 2024. The clinical characteristics, treatment, and survival prognosis were then analyzed.

Results There were 32 patients, of which 18 were male and 14 female. The median age was 56 years. Nine patients had typical carcinoid and 23 had atypical carcinoid, with six in stage Ⅲ and 26 in stage Ⅳ. The common metastatic sites included the bones (18 cases), lungs (8 cases), pleura (7 cases), and liver (7 cases). The median length of the measurable primary tumor was 5.2 cm, which was mostly located centrally (22 cases). Five among the 16 patients who underwent somatostatin receptor (SSTR) imaging had high SSTR expression. The initial symptoms mainly included respiratory symptoms, and none of them were combined with carcinoid syndrome. For the first-line treatment, 19 patients were treated with chemotherapy, seven were treated with targeted therapy, four were treated with somatostatin analogs (SSAs), and two were treated with surgery. The best efficacy was evaluated as a partial response in one case (3.1%), stable disease in 23 cases (71.9%), and non-evaluable or unknown in eight cases (25%) in the first-line treatment. The median progression-free survival (mPFS) of patients who received first-line treatment was 5.2 months (95%CI: 0.0-13.9). The PFS of targeted therapy was the longest (11.0 months, 95%CI: 0.0-29.6), but there was no significant difference compared with the PFS of chemotherapy and SSA groups (P>0.05). The longest PFS (24.5 months, 95% CI: 0.0-58.7) was found in patients treated with chemotherapy combined with radiotherapy, but there was no significant difference compared to the PFS of the combined immunotherapy and combined anti-angiogenesis groups (P>0.05). The survival rates at 1, 3, and 5 years were 79.1%, 65.5%, and 58.9%, respectively. Cox regression analysis did not identify independent risk factors for prognosis.

Conclusions The initial symptoms of patients with locally advanced or metastatic NETs were mainly respiratory symptoms but without specific manifestations. Some of them were accompanied by high SSTR expression, and there was generally no carcinoid syndrome. The first-line systemic therapy mainly included chemotherapy and target therapy, with relatively low objective response and high disease control rates. Targeted therapy and combined radiotherapy have longer PFS than that of chemotherapy. The overall survival of patients with pulmonary NETs was good.