Treatment Times in Salivary Gland Cancer: National Patterns and Association with Survival

Objective To characterize treatment times in salivary cancer; associate treatment times with patient, tumor, and treatment characteristics; and examine the association of treatment times and overall survival. Study Design Retrospective cohort. Setting Commission-on-Cancer Accredited Hospitals 2004-2013. Subjects and Methods In total, 5953 patients with salivary cancer included in the National Cancer Database were identified. For each treatment interval, patients in the fourth quartile ("prolonged") were compared to patients in the first and second quartiles ("not prolonged"). Patient, tumor, and treatment characteristics were associated with prolonged times via multivariable binary logistic regression. Prolongation of each interval was associated with overall survival via multivariable Cox proportional hazards regression, controlling for clinically relevant factors. Results Median durations for diagnosis-to-treatment initiation, surgery-to-radiation treatment (RT), RT duration, total treatment package, and diagnosis-to-treatment end were 31, 44, 47, 92, and 110 days, respectively. Race, insurance status, comorbidities, age, T and N stage, facility volume and location, and a facility care transition from diagnosis to initial treatment were associated with prolonged treatment time. Prolonged RT duration was associated with decreased overall survival (OS) (62% vs 75% 5-year OS, HR = 1.26 [95% confidence interval (CI), 1.09-1.47]; P = .002), but prolonged diagnosis-to-treatment initiation, surgery-to-RT, total treatment package, and diagnosis-to-treatment end intervals were not (70% vs 67% 5-year OS, HR = 1.11 [95% CI, 0.92-1.34], P = .284; 72% vs 68%, HR = 0.93 [95% CI, 0.79-1.09], P = .370; 70% vs 70%, HR = 1.00 [95% CI, 0.84-1.20], P = .974; 66% vs 71%, HR = 0.99 [95% CI, 0.84-1.18], P = .920, respectively). Conclusion The median durations identified here can serve as reference points. Radiation therapy duration is associated with overall survival in salivary cancer and could be considered a quality indicator.