Abstract
BACKGROUND: Tracheal adenoid cystic carcinoma (TACC) is a rare malignant tumor with limited treatment options for unresectable cases. Although case reports have indicated the value of photodynamic therapy (PDT), its efficacy, survival outcomes, and prognostic factors remain poorly characterized. This two-center retrospective study aimed to evaluate the long-term outcomes of patients with TACC treated with PDT and to identify predictors of treatment response. METHODS: A retrospective analysis was conducted on 39 patients with TACC who received continuous PDT treatment in two hospitals from August 2011 to September 2023. All patients were intravenously injected with hematoporphyrin derivative (HpD) at a dose of 2 mg/kg and treated 48 hours later. The therapeutic effect was evaluated according the 2019 efficacy evaluation standard for PDT for respiratory tumors. The primary endpoints were overall survival (OS) and progression-free survival (PFS), while the secondary endpoints included objective response rate (ORR) and safety. The prognostic factors were analyzed via a Cox regression model. RESULTS: The study included 39 patients, with a mean age of 47.51±14 years (range, 19-79 years). The most recent efficacy evaluation of 39 patients, conducted 1 month after PDT treatment, showed complete response (CR) in 5 patients, partial response (PR) in 25 patients, and progressive disease (PD) in 9 patients. Both OS and PFS were significantly longer in the PR group than in the PD group (OS: P=0.008; PFS: P=0.005). The 5-, 10-, and 15-year survival rates for patients were 73.2%, 64.1%, and 42.7%, respectively. Only 7 patients experienced complications. Univariate Cox regression analysis indicated that the age and treatment interval were significant risk factors for the emergence of TACC (P=0.03). CONCLUSIONS: We found that PDT for patients with TACC achieved satisfactory clinical efficacy and safety, resulting in longer survival and fewer complications. Moreover, treatment interval and age were risk factors for the development of TACC.