Data-derived treatment duration goal for cervical cancer: Should 8 Weeks remain the target in the era of concurrent chemoradiation?

Purpose Prior studies have demonstrated the importance of treatment duration (TD) in radiation therapy (RT) for cervical cancer, with an 8-week goal based primarily on RT alone. This study uses a contemporary cohort to estimate the time point by which completion of chemoradiation therapy is most critical. Patients and Methods The National Cancer Database was queried for women with nonmetastatic cervical cancer diagnosed from2004to2012whounderwent chemotherapy, externalbeamRT, and brachytherapy. Data-derived TD cut points for overall survival (OS) were computed by using recursive partitioning analysis with bootstrapped aggregation (bagging) and 10-fold cross-validation. Models were independently trained with 70% of the population and validated on 30% of the population by log-rank test with and without propensity matching.Multivariable Cox proportional hazards regressionwas performed for the entire cohort. Results In all, 7,355 women were identified with a median TD of 57 days. Bagged recursive partitioning analysis converged to a mean cut point of 66.6 days (median, 64.5 days; interquartile range, 63.5 to 68.5 days). Cross-validation yielded a cut point of 63.3 days. Both cut points differentiated OS in validation. Younger age, recent diagnosis, geographic region, nongovernment insurance, shorter distance to treatment facility, metropolitan location, lower comorbidity, squamous cell carcinoma, lower stage, negative lymph nodes, and shorter TD were independently associated with longer OS. With adjustment, TD within the mean cut point (64.9 days; hazard ratio, 0.79; 95% CI, 0.73 to 0.87) and 56 days (hazard ratio, 0.87; 95% CI, 0.80 to 0.95) were associated with longer OS. Exploratory stratification suggested increasing OS detriment beyond 64 days. Conclusion Shorter chemoradiation TD in cervical cancer is associated with longer survival, and TD should be minimized as much as possible. The data-derived cut point was distributed around 64 days, with a continuous relationship between shorter TD and longer OS.