KEY POINTS
- DAHANCA identified 331 patients with nonmetastatic nasopharyngeal carcinoma treated with curative-intent RT across Denmark between 2000 and 2018, with potential follow-up extending beyond five years.
- Definitive treatment generally delivered 66–68 Gy in 33–34 fractions to gross/high-risk disease, approximately 60 Gy to elective high-risk regions and ≥50 Gy to lower-risk nodal volumes. IMRT gradually replaced older techniques and was used in 249 patients (75.2%).
- At five years, cumulative incidence was 31.1% for any failure, 16.9% for locoregional failure and 14.2% for distant failure, corresponding to an estimated locoregional control of approximately 80.5%.
- Distant failure was strongly stage-dependent: 0% in stage I, 4.2% in stage II, 21.1% in stage III and 19.4% in stage IVa, indicating that metastatic relapse was largely a problem of locally advanced disease.
- EBV status did not clearly separate failure risk. Failure occurred in 29.7% of EBV-positive versus 32.0% of EBV-negative tumors (p=0.3), with no significant difference in failure distribution. Median time to failure was 16 versus 10 months, respectively, with overlapping interquartile ranges.
- IMRT itself was not associated with a lower five-year locoregional-failure incidence in this historical cohort: 16.9% with IMRT versus 17.1% without IMRT, although this comparison spans major changes in staging, imaging and systemic treatment over nearly two decades.
- The key limitation is the long 2000–2018 treatment era, during which RT technology, chemotherapy use and diagnostic staging evolved substantially. EBV status was also available for only a subset of the cohort, limiting power for biomarker comparisons.
CLINICAL TAKEAWAY
In a low-incidence European population, EBV-negative NPC did not show a clearly worse post-RT failure pattern than EBV-positive disease. Stage remained much more informative for distant-failure risk, although modern prospective cohorts with routine EBV testing and contemporary systemic therapy are needed before extrapolating these findings to current practice.