A Comparative Population-Based Study of Tracheal and Lung Adenoid Cystic Carcinoma

Abstract

Thoracic adenoid cystic carcinoma (ACC) is very rare, and its clinicopathological characteristics, treatment and prognosis have not been fully elucidated. Previous studies did not differentiate between tracheal and lung lesions. We identified tracheal ACC (TACC) and lung and bronchus ACC (LACC) patients from our cancer center (from 2005 to 2022) and the Surveillance, Epidemiology, and End Results (SEER) database (from 2000 to 2009). Incidence was calculated and trends were quantified. Significant prognostic factors for overall survival (OS) were reviewed and analyzed by using Cox proportional hazards regression. Then, two nomograms predicting OS of TACC and LACC were constructed based on the SEER database and validated externally by using the separate cohort. There was an upward trend from 2000 to 2019 for LACC while a downward trend from 2000 to 2009 was shown for TACC. Totally, 55 TACC and 25 LACC were included in our cohort, 121 TACC and 162 LACC included in the SEER cohort. There were larger tumor sizes, more lymph nodes and distant metastases for LACC patients than TACC patients. The proportion of patients receiving radiotherapy were higher for TACC than LACC. More patients with TACC received surgery and perioperative radiotherapy than those with LACC. Patients with LACC had significantly worse OS than patients with TACC (SEER cohort: 93.7 mons vs. 127.0 mons, p = 0.001, our cohort: 72.2 months vs. 130.8months, p = 0.061). Age, lymph node metastasis, distant metastasis and radiation and/or surgery were identified as independent prognostic factors for OS of TACC. Laterality, distant metastasis and surgery were identified for LACC. The discrimination of the nomogram revealed good prognostic accuracy and clinical applicability as indicated by C-index values of 0.753 and 0.833 for the training cohort and the external validation cohort for TACC, and 0.739 and 0.786 for LACC. TACC and LACC are different in incidence, clinical features, prognosis. Compared with LACC, radiotherapy combined with surgery is more important for TACC. Two nomograms were established for TACC and LACC respectively to help physicians make more individualized survival predictions and clinical decisions.