Although the survival rate of nasopharyngeal cancer (NPC) patients has significantly improved in the last decade, few studies have quantified the long-term morbidity and mortality that follow NPC treatment.¹ To address this knowledge gap, local researchers conducted the Hong Kong NPC Survivor Study (HKNPCSS) to analyze the risk of chronic health conditions, all-cause mortality, and cause-specific mortality among NPC survivors.¹ At the 2024 ASCO Annual Meeting, Dr. Chiang, Chi-Leung shared the findings from this study.¹

This retrospective cohort study involved a longitudinal follow-up of NPC 5-year survivors diagnosed during 1997-2015 across 6 Hong Kong oncology centers.¹ Among the 8,990 NPC 5-year survivors in Hong Kong, those with synchronous distant metastasis, declined radical radiotherapy, or received treatment and follow-up in private, were excluded from the study.¹ In total, 7,893 primary NPC 5-year survivors (HKNPCSS cohort) and 23,679 healthy individuals with matched age, sex and date of cohort entry (healthy cohort) were included in the study.¹ To compare mortality rates in the HKNPCSS population with the matched healthy population, standardized mortality ratios (SMRs) were calculated.¹ The frequencies of chronic conditions in these two groups, as classified using the Common Terminology Criteria for Adverse Events (CTCAE) were also compared.¹

The mean ages of NPC survivors and healthy individuals were 49.1 and 50.5 years respectively.¹ Among the NPC survivors, the 20-year cumulative all-cause mortality was 34.0%, of which 59.9% were from health-related causes.¹ The all-cause SMR of NPC survivors to the general population was 3.81 (95% CI: 3.67-3.95), with the highest SMRs observed for pulmonary (SMR=6.18; 95% CI: 5.73-6.64) and cardiovascular (SMR=2.12; 95% CI: 1.90-2.36) causes.¹ Higher SMRs of NPC survivors to healthy individuals were also seen across various subgroups, including sex, age at diagnosis, disease stage, treatment with or without chemotherapy, and radiotherapy technique used.¹

Moreover, this study found that NPC survivors have higher frequencies of any grade 3-5 chronic conditions compared to the healthy cohort (59.2% vs. 15.9%; HR=7.02; 95% CI: 6.64-7.42), as well as higher cumulative incidence by 20 years after diagnosis (59.0% vs. 11.3%; HR=6.37; 95% CI: 6.02-6.74).¹ In particular, compared to the healthy cohort, NPC survivors were at particularly higher risks of grade 3-5 chronic gastrointestinal (HR=20.7; 95% CI: 17.6-24.4), hearing, visual and nasal (HR=15.4; 95% CI: 12.7-18.6), and neurological conditions (HR=8.39; 95% CI: 7.12-9.88).¹

Lastly, this study also found that intensity-modulated radiotherapy (IMRT), compared to non-IMRT, was significantly associated with reduced risks of all-cause mortality (HR=0.83; 95% CI: 0.71-0.98; p=0.023) and showed a trend towards reduced grade 3-5 chronic health conditions (HR=0.89; 95% CI: 0.75-1.05).¹

In conclusion, even 20 years after diagnosis, NPC survivors still face increased risks of late mortality and morbidity.¹ There is a need for a comprehensive survivorship program to improve outcomes in NPC survivors.¹