Validation of T classifications in the 7th edition UICC staging system and recommendation of a simpliifed T classiifcations based on intensity-modulated radiotherapy / 中国癌症杂志

ABSTRACT

Background and purpose:The application of intensity-modulated radiotherapy (IMRT) has improved the local control rate of nasopharyngeal carcinoma greatly, which changed the predictive value of T classiifca-tions of TNM staging system. This study aimed to validate the predictive effect of T classiifcations in the 7th Union for International Cancer Control (UICC) staging system and discuss the simpliifcation of T classiifcations.Methods:We retrospectively reviewed the clinical data of 641 primary nasopharyngeal carcinoma patients at our center from January 2007 to June 2011. We evaluated the predictive effect of T classiifcations by Kaplan-Meier method and Cox regression model.Results:The 5-year overall survival (OS), local relapse-free survival (LRFS), progression-free survival (PFS) and distant metastasis free survival (DMFS) were 85.4%, 88.5%, 78% and 87.1%, respectively. The 5-year OS of T1, T2, T3 and T4 categories were 91.6%, 85.3%, 90.1% and 76.5%, respectively; LRFS were 93%, 85.3%, 91.5% and 84.4%; PFS were 88.2%, 77.3%, 80.8% and 70.9%; DMFS were 95.1%, 88.9%, 88.2% and 81.3%, respectively. The difference in survival curves between T1, T2 and T3 were not signiifcant (P>0.05). However, several prognostic indexes were signiifcantly different between T4 and T1, T2, T3. We merged the T1, T2 and T3 classiifcations as new T1, and the T4 classiifcation as new T2. The 5-year OS of new T1 and T2 were 89.1% and 76.5% (P=0.001); LRFS were 90.1% and 84.4% (P=0.028); PFS were 81% and 70.9% (P=0.001); DMFS were 90.8% and 81.2% (P=0.002). The survival curves were substantially separated. The simpliifed T classiifcations had obvious advantages when separately analyzed in different N stages.Conclusion:In the era of IMRT, the predictive effect of T classiifcations of the 7th UICC staging system has diminished. The simpliifcation of T classiifcations can ift with the new treatment and provide a better surviv-al prediction.