Intensity-modulated radiation therapy with simultaneous integrated boost technique following neoadjuvant chemotherapy for locoregionally advanced nasopharyngeal carcinoma

Background. Our aim was to evaluate the feasibility and efficacy of intensity-modulated radiation therapy (IMRT) with simultaneous integrated boost (SIB) technique following neoadjuvant chemotherapy for locoregionally advanced nasopharyngeal cancer (NPC). Methods. Between April 2004 and December 2006, 25 patients with stage IIB to IVB NPC underwent 3 cycles of neoadjuvant chemotherapy followed by IMRT using SIB technique. Neoadjuvant chemotherapeutic regimens were 5-fluorouracil and cisplatin in 11 patients; docetaxel, 5-fluorouracil, and cisplatin in 8; and paclitaxel and cisplatin in 6. Dose prescription of IMRT was as follows: 67.5 Gy at 2.25 Gy/fraction to postchemotherapy gross tumor, 54 to 60 Gy at 1.8 to 2 Gy/fraction to subclinical disease, and 48 Gy at 1.6 Gy/fraction to elective neck. Seventeen patients received weekly cisplatin during the course of radiation therapy as well. Results. With a median follow-up of 29 months for survivors (range, 14-39), the 3-year local progression-free, regional progression-free, and distant metastasis-free survival rates were 89.6%, 87.2%, and 80.4%, respectively. Treatment was well tolerated despite the grade 3 mucositis (16%) and/or pharyngitis (16%). With follow-up, the frequency of xerostomia decreased. At 3 months after IMRT, the proportions of Radiation Therapy Oncology Group grades 0, 1, and 2 xerostomia were 13%, 38%, and 50%, respectively. At 24 months, the corresponding figures were 36%, 46%, and 18%, respectively. Conclusion. IMRT with SIB technique for locoregionally advanced NPC was feasible and effective regarding locoregional control and development of xerostomia, even after neoadjuvant chemotherapy. Definition of gross tumor volume by postchemotherapy extent of disease was also feasible.