Association between the diagnosis-to-treatment interval and overall survival in Taiwanese patients with oral cavity squamous cell carcinoma

Background: To investigate the association between the diagnosis-to-treatment interval (DTI) and overall survival (OS) in patients with oral cavity squamous cell carcinoma (OSCC). Methods: A total of 18,677 patients with first primary OSCC identified in the Taiwanese Cancer Registry Database between 2004 and 2010 were examined. The effect of DTI on 5-year OS rates was investigated with multivariate Cox regression analysis. After the identification of the optimal cutoff for DTI based on the 5-year OS rates, DTI was classified in the following 20 day groups: <= 20 days (57% of the study patients), 21-45 days (34%), 46-90 days (6%) and >= 91 days (3%). In additional exploratory analyses, DTI was reclassified in the following 30 day interval groups: <= 30 days (81% of the study patients), 31-60 days (14%), 61-90 days (2%) and >= 91 days (3%). Results: Multivariate analyses identified DTI (<= 20 days versus other subgroups), sex (female versus male), age (<65 versus >= 65 years), clinical stage (p-stage I versus p-stage II, III, IV) and treatment modality (initial surgery versus initial non-surgery) as independent prognostic factors for 5-year OS. Compared with a DTI <= 20 days, the DTI categories >= 91 days (hazard ratio [HR]: 1.28, P < 0.001), 46-90 days (HR: 1.25, P < 0.001) and 21-45 days (HR: 1.07, P = 0.007) were independently associated with a higher risk of 5-year mortality. Similar results were obtained for DTI <= 30 days groups. Conclusions: DTI is independently associated with 5-year OS in OSCC patients. A DTI longer than 30 days or even 20 days may potentially decrease survival. (C) 2016 Elsevier Ltd. All rights reserved.