In the f 2 (1270)-f 2 (1525) mixing framework, the isoscalar singlet-octet mixing angle for the 1 3 P 2 tensor nonet is determined to have the value of 27.5 • and the decays of the two states are investigated. Comparing the predicted results of the decays of the two states with the available experimental data, we find that the predicted results based on this simple mixing picture are in good agreement with the experimental data, which show that the f 2 (1270) and f 2 (1525) wavefunctions do not need other components such as glueballs or the 2 3 P 2 , 3 3 P 2 , . . . , qq.

BackgroundEsophageal neuroendocrine carcinomas (NECs) are exceedingly rare and poorly understood. The aims of the retrospective study were to delineate the clinicopathologic features and prognosis of patients with the disease.MethodsWe performed a retrospective study containing 53 patients of esophageal NECs in our center from 2002 through 2018. Patients were assigned to the pure esophageal NECs group and the esophageal NECs mixed with squamous carcinoma and/or esophageal adenocarcinoma (MiNECs) group. Demographic, clinical, pathologic and prognostic factors were recorded and analyzed.ResultsOf the 53 patients, elderly male patients were predominant. Dysphagia was the most common symptom (45/53, 84.9%). Most tumors were centered in the middle esophagus (36/53,67.9%).Ulcerated appearance was frequently seen in the pure NECs (56.8%), and the tumors in the MiNECs group mostly represented elevated types (57.9%). Synaptophysin (38/45, 84.4%), chromogranin A (21/38, 55.3%) and CD56(23/27, 85.2%) have been proven to be positive markers for NECs. Most patients (46/53, 86.8%) received surgery combined with chemotherapy. Though the pathologic stages were alike (P = 0.129), the median survival time was 3.53 years for the pure NECs group and 7 years for the MiNECs group. In multivariate analysis, pathologic stage (RR = 1.938, P = 0.045) and age (RR = 2.410, P = 0.028) were independent prognostic factors for patients with MiNECs. The prognosis of patients with pure NECs was independent from any factors.ConclusionsCareful endoscopic examination could help distinguish pure NECs from MiNECs. NECs were aggressive, but a relative better prognosis for patients with MiNECs. Surgery should be performed if applicable, and chemotherapy might be helpful.