Factors Affecting Survival of Nasopharynx Cancer (NPC) Patients in Northeast Thailand after Radiation Treatment

Abstract

Background and Objective : Cancer of the nasopharynx (NPC), in Thailand patients are frequently diagnosed at a late stage, when practical treatment options are limited to radiotherapy. The factors affecting survival after late-stage radiation treatment have not been adequately studied.

Objective : This study attempted to determine the factors associated with survival among NPC patients after radiation treatment in the Northeastern Thailand.

Methods: A retrospective study was performed on the records of 1,129 patients, retrieved from the database of the Radiotherapy Unit, Faculty of Medicine, Khon Kaen University . The NPC patients receiving radiotherapy were recruited between January 1, 1994 and December 31, 2007.  All of the patients  had histologicaly proven NPC and were followed up until July 31, 2008.  The potential factors affecting survival included: age, sex, stage of disease, histological grading, pathology type, lymph node, T4 parameters and distant metastases (including to the liver, brain, bone, lung and nodes).  Survival analysis wereperformed by the Kaplan-Meier method.  The Cox proportional Hazard Model was used to assess the association of  independent variables with survival .

Results: Overall, 719 patients died during the study, corresponding to a mortality (case-fatality) rate of 19.8 per 100 person-years (95%CI: 18.4-21.4). The Median follow up time was 7.5 years. The median survival after radiation treatment was 2.3 years (95% CI: 2.0 -2.5).  The overall survival rates at 1-3-5 yrs, were 72.7% (95% CI: 70.0-75.3), 43.9 (95%CI: 41.0-45.9) and 34.5 (95%CI: 31.4-37.5).  After adjusting for age, sex, stage, pathology type, and T4 parameters the significant predictors included  age, sex, stage and T4 parameters.

Conclusions: NPC patients could survive 3 yrs. and 2 months after radiation treatment, and had an increased mortality risk at the late stage, especially age more than 45 yrs.

Keywords: Nasopharynx cancer, Prognostic factors, Radiation therapy