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.
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