Excessive mortality in 1,353 five-year survivors of nasopharyngeal cancer

Abstract

Background: Survival of NPC patients has improved in past decades. Yet, survivors continue to face elevated risks of life-threatening late effects. Their impact on late mortality remains poorly quantified. Methods: 1353 five-year NPC survivors diagnosed between 1997 and 2013 at Queen Mary Hospital were reviewed. Their demographics and treatment data were taken from electronic medical records. Survival probability, standardized mortality ratios (SMRs) and absolute excessive risk were calculated for overall and cause-specific deaths. Results: At median follow-up time of 12.4 years, 412 (30.5%) five-year survivors had died at the time of analysis. 66.2% of deaths attributed to non-recurrence death. Estimated 10-, 15-, and 20-year survival probability were 81.4%, 67.6%, and 57.3% respectively. Compared to Hong Kong general population, absolute excessive risk of death from any causes was 17 deaths per 1000 person-years; overall SMR was 3.52 (95% CI: 3.19 to 3.87, p<0.001). 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). Conclusions: Five-year NPC survivors still face excessive mortality long after diagnosis, and majority of death was from non-recurrence death. Further analyses are needed to determine predictive factors of excessive mortality.