Incidence and Predictive Factors of Late Mortality in 1353 Five-year Survivors of Nasopharyngeal Cancer (NPC)

Abstract

Purpose/Objective(s) The proportion of nasopharyngeal cancer (NPC) patients surviving 5 years has improved in past few decades. This growing population remains at risk of late mortality due to life-threatening complications. This study aims at evaluating its incidence and predictive factors in a large single-institutional cohort. Materials/Methods A total of 1353 five-year survivors of NPC diagnosed between 1997 and 2013 at Queen Mary Hospital were analyzed. Patients’ demographics and treatment information was abstracted from electronic medical records. Survival probabilities, standardized mortality ratios (SMRs), and absolute excessive risks were calculated for overall and cause-specific deaths. Results The median follow-up was 12.4 years. 421 (31.1%) five-year survivors had died at the time of analysis; 65.9% was attributed to non-recurrence death. The cumulative mortality of non-recurrence death exceeds recurrence death at 10-, 15-, 20 years (10.0% vs. 7.1%; 17.1% vs. 9.5%, and 20.2% vs. 10.3% respectively). Compared with Hong Kong general population, the absolute excessive risk of death were 17.7 deaths per 1000 person-years; the overall SMR was 3.59 (95% CI = 3.26 to 3.95). Increases in cause-specific mortality were seen for death due to pulmonary (SMR = 6.75; 95% CI = 5.67 to 7.98) and secondary malignancy (SMR = 1.41; 95% CI = 1.06 to 1.83). Male sex, advanced age, re-irradiation, and smoking were independent factors of excessive late mortality. Conclusion NPC survivors continue to face excessive risk late mortality and majority was attributed to non-recurrence death. Further validation of our findings in multi-center setting is warranted.