KEY POINTS
- Retrospective single-institution study of 909 patients with stage III-IVB nasopharyngeal carcinoma treated with definitive intensity modulated radiotherapy from 2012 to 2022.
- 145 patients (16.0%) had gross tumor volume-to-cervical spinal cord distance ≤2 cm; among them, 106 (73.1%) received target-prioritized planning when adequate target coverage could not be achieved under conventional spinal cord planning organ-at-risk volume constraints.
- In the overall cohort, median follow-up was 76.11 months; no clinically diagnosed radiation myelopathy was observed, with an upper one-sided 95% confidence interval of 0.33%.
- In the target-prioritized cohort, median planning organ-at-risk volume cord Dmax was 56.2 Gy, and 22 patients (20.8%) had Dmax >60 Gy; high-dose volumes remained small, with median planning organ-at-risk volume V60 0.000 cm³ in the full target-prioritized cohort.
- With median follow-up of 93.24 months in the target-prioritized cohort, 5-year local relapse-free survival was 87.9%, 5-year overall survival was 74.2%, and no clinically diagnosed radiation myelopathy was observed, although 5 of 78 documented patients reported transient Lhermitte’s sign.
CLINICAL TAKEAWAY
This study provides useful real-world evidence for selected nasopharyngeal carcinoma cases where target coverage and spinal cord protection are in direct conflict. It suggests that target-prioritized planning with strict image guidance and very limited high-dose cord volumes can be feasible, but the retrospective design, rare toxicity endpoint, incomplete neurologic documentation, and lack of pre-relaxation plan comparisons mean it should not be used to loosen current spinal cord constraints.