KEY POINTS
- The review groups toxicity-reduction strategies into three dimensions: spatial precision, including response-guided target volumes and adaptive radiotherapy; temporal optimization, including altered treatment sequencing; and energy selection, principally proton therapy.
- In a randomized phase 3 trial of 449 patients, response-guided reduced-volume radiotherapy after induction chemotherapy produced three-year locoregional recurrence-free survival of 94.3% versus 90.5%, meeting the prespecified non-inferiority criterion.
- Reduced-volume treatment lowered grade 3 or higher oral mucositis from 56.9% to 34.0% and also reduced xerostomia and hearing loss. Post-induction-chemotherapy target delineation has subsequently been incorporated into international recommendations.
- A second phase 3 trial involving 468 patients reported three-year failure-free survival of 83.7% with sequential chemoradiotherapy versus 79.5% with induction followed by concurrent chemoradiotherapy.
- Sequential treatment reduced grade 3 or higher acute toxicity during radiotherapy from 58.6% to 34.8%, but prolonged treatment sequencing and should be considered an alternative for selected patients rather than a universal replacement for concurrent cisplatin.
- Proton planning studies report dose reductions of approximately 30–50% to structures including the parotids, cochlea, swallowing muscles, brainstem and temporal lobes. No phase 3 comparison has demonstrated improved clinical outcomes for newly diagnosed nasopharyngeal carcinoma.
- Immunotherapy-based chemotherapy de-escalation and artificial-intelligence-supported integration of imaging, Epstein-Barr-virus DNA and multi-omics remain investigational. The review also cites a prostate-cancer proton comparison in its summary table, weakening the disease-specific evidence synthesis.
CLINICAL TAKEAWAY
Response-guided target reduction after induction chemotherapy currently has the clearest evidence for reducing toxicity without compromising control. Sequential chemoradiotherapy may help selected patients unable to tolerate concurrent treatment, while proton therapy and immunotherapy-based de-escalation require stronger disease-specific comparative evidence; this review is a conceptual framework rather than a guideline.