Background
Phase II single-arm prospective multicenter trial (RTOG 0225). N=68 previously untreated NPC (T1–T4, N0–N3, M0) treated with IMRT to prospectively validate IMRT for NPC (vs historical 2D techniques with high xerostomia). 80% received concurrent cisplatin.
Interventions and follow up
Treatment: IMRT with simultaneous integrated boost — 70 Gy GTV high-risk, 59.4 Gy intermediate-risk CTV, 54 Gy low-risk CTV, all in 33 fractions; 80% received concurrent cisplatin
Primary endpoint: 2-yr locoregional control; secondary: xerostomia
mFollow up: Median 31 mo
Primary endpoint: 2-yr locoregional control; secondary: xerostomia
mFollow up: Median 31 mo
Results
2-yr locoregional control: 93.5%
2-yr PFS: 73.3%
2-yr OS: 80.2%
Grade ≥2 acute xerostomia: 68%
Grade ≥2 late xerostomia (12 mo): 37% (substantially lower than historical 2D RT)
2-yr PFS: 73.3%
2-yr OS: 80.2%
Grade ≥2 acute xerostomia: 68%
Grade ≥2 late xerostomia (12 mo): 37% (substantially lower than historical 2D RT)
Adverse events
Grade ≥3 acute mucositis: 25%
Grade ≥3 xerostomia: 12% acute, 7% late at 12 mo (vs 60–80% grade ≥2 late with 2D RT)
Hearing loss grade ≥2: 22%
Mandibular osteoradionecrosis: Rare (<2%)
Grade ≥3 xerostomia: 12% acute, 7% late at 12 mo (vs 60–80% grade ≥2 late with 2D RT)
Hearing loss grade ≥2: 22%
Mandibular osteoradionecrosis: Rare (<2%)
Conclusions
IMRT for NPC achieves excellent 2-yr locoregional control (93.5%) while significantly reducing salivary gland toxicity and xerostomia vs conventional 2D radiotherapy. This prospective validation established IMRT as the standard of care for NPC treatment planning.
Key Limitations
Single-arm phase II, no randomized comparator; modest N=68; short median follow-up (31 mo) for late toxicity and durability; xerostomia comparison vs historical 2D data rather than concurrent control.
Clinical Context
Pivotal cooperative-group validation that established IMRT (with concurrent cisplatin) as standard radiotherapy for NPC, prioritizing parotid sparing to reduce chronic xerostomia.