Impact of prior cancer on outcomes in nasopharyngeal carcinoma

Huaqiang Zhou, Yaxiong Zhang, Jiaqing Liu, Wenfeng Fang, Yunpeng Yang, Shaodong Hong, Gang Chen, Shen Zhao, Jiayi Shen, Wei Xian, Zhonghan Zhang, Xi Chen, Hongyun Zhao, Yan Huang, Li Zhang


Background: Prior cancer is a common exclusion criterion in nasopharyngeal carcinoma (NPC) trials. However, whether a prior cancer diagnosis affects trial outcomes is still unknown. We aimed to determine the impact of prior cancer on survival in NPC patients.
Methods: We identified patients diagnosed with NPC between 2004 and 2009 in the Surveillance, Epidemiology, and End Results (SEER) database. Variables were compared by chi-squared test and t-test as appropriate. Propensity score-adjusted Kaplan-Meier methods and Cox proportional hazard models were used to evaluate the impact of prior cancer on overall survival (OS).
Results: Among 3,131 eligible NPC patients, 349 (11.15%) patients had a history of prior cancer. The Kaplan-Meier curves did not show a statistically significantly different OS (P=0.19). Subgroup analyses stratified by timing of prior cancer and AJCC TNM stage of index cancer displayed the same tendency: prior cancer did not adversely affect OS compared to patients without prior cancer (P>0.05). Furthermore, in propensity score-adjusted COX models analysis, patients with prior cancer had the same/non-inferior OS [hazard ratio (HR) =1.12; 95% confidence interval, 0.88 to 1.42].
Conclusions: Among patients with NPC, prior cancer does not convey an adverse effect on clinical outcomes, regardless of the timing of prior cancer and AJCC TNM stage of index cancer. Broader inclusion trial criteria could be adopted in NPC patients with a history of prior cancer. However, further studies are still needed to confirm this conclusion.