Effectiveness of three-dimensional conformal radiotherapy for treating early primary nasopharyngeal carcinoma

In 2-dimensional radiotherapy, the irradiating portal is defined mainly by soft tissues and bony structures, so the exact location of nasopharyngeal tumors and many spatial relationships are unknown, resulting in high local-regional relapse rates and radiation toxicities. Three-dimensional conformal radiotherapy (3D CRT) provides more precise targeting of radiation. We studied whether 3D CRT could maintain survival and increase local-regional tumor control whereas reducing the morbidity and severity of radiation toxicity in patients with early primary nasopharyngeal carcinoma (NPC).

Patients with histologically proven keratinizing or nonkeratinizing undifferentiated NPC (T₁₋₂N₀₋₁M₀ stage) received a prescribed 3D CRT dose of 70 Gy to the gross tumor volume (GTV(nx)), 60 Gy to the GTV(nx) with an additional 5- to 10-mm margin (CTV(nx)₆₀), 60 to 70 Gy to the region involved by the metastatic lymph nodes (GTV(nd)), and 50 Gy to the prophylactic irradiating region (CTV(nd)₅₀).

Of 58 patients enrolled between August 2001 and December 2006, (48 men; median age, 46 years; range, 29-69 years), 15 had stage I and 43 had stage II disease. At 5 years, overall survival was 95% and disease-free survival was 91%; 93% of patients were free of local-regional recurrence and 98% were free of distant metastases. Grade 2 or 3 xerostomia occurred in 7 patients and trismus occurred in 5. Mean standard deviation (SD) dental gap was 37.4 (6.9) mm. Four patients had recurrent lesions, mainly in-field.

The survival and morbidity provided by 3D CRT were excellent in these patients with early NPC.