Abstract
A planning study was performed in order to investigate the potential benefits of intensity-modulated radiotherapy using a simultaneous integrated multi-target treatment technique (SIMT-IMRT) over highly optimized three-dimensional conformal radiotherapy combined with intracavitary brachytherapy (3D-CRT + IBT) for the treatment of nasopharyngeal carcinoma (NPC). The subjects were eight patients with Stages I–IV NPC. For each case, two sets of plans were prepared after delineation of gross tumour volumes, three planning target volumes (PTVs) and 17 organs at risk (OARs). Dose prescriptions for PTVs were 72.6 Gy, 66 Gy and 52.8 Gy in 33 fractions for SIMT-IMRT vs 72 Gy (66 Gy in 33 fractions for 3D-CRT and 3 Gy twice for IBT), 66 Gy (in 33 fractions) and 46 Gy (in 23 fractions) for 3D-CRT + IBT plans. Compared with the combined plans, SIMT-IMRT provided superior results for the primary tumour (PT) in terms of mean equivalent uniform dose (67 Gy vs 63.7 Gy, p = 0.016). IMRT plans increased the mean tumour control probability (TCP) values (both uncorrected and corrected for accelerated tumour repopulation after 28 days) for PT when compared with 3D-CRT + IBT (98% and 94.3% vs 95.8% and 89.9%, respectively, p = 0.016). Mean doses to middle/external ears, parotid glands and temporomandibular joints were significantly lower in IMRT plans. Our conclusion is that, for all stages of NPC, SIMT-IMRT was superior to highly optimized 3D-CRT + IBT in terms of tumour coverage, increased local TCP, and dose reduction to some OARs. We recommend that SIMT-IMRT should be considered as a first-line radiotherapy technique for NPC.
References
1 Leibel SA, Kutcher GJ, Harrison LB, Fass DE, Burman CM, Hunt MA, et al. Improved dose distributions for 3D conformal boost treatments in carcinoma of the nasopharynx. Int J Radiat Oncol Biol Phys 1991;20:823–33.
2 Teo PM, Leung SF, Lee WY, Zee B. Intracavitary brachytherapy significantly enhances local control of early T-stage nasopharyngeal carcinoma: the existence of a dose-tumor-control relationship above conventional tumoricidal dose. Int J Radiat Oncol Biol Phys 2000;46:445–58.
3 Wolden SL, Zelefsky MJ, Hunt MA, Rosenzweig KE, Chong LM, Kraus DH, et al. Failure of a 3D conformal boost to improve radiotherapy for nasopharyngeal carcinoma. Int J Radiat Oncol Biol Phys 2001;49:1229–34.
4 Kam MK, Chau RM, Suen J, Choi PH, Teo PM. Intensity-modulated radiotherapy in nasopharyngeal carcinoma: dosimetric advantage over conventional plans and feasibility of dose escalation. Int J Radiat Oncol Biol Phys 2003;56:145–57.
5 Hunt MA, Zelefsky MJ, Wolden S, Chui CS, LoSasso T, Rosenzweig K, et al. Treatment planning and delivery of intensity-modulated radiation therapy for primary nasopharynx cancer. Int J Radiat Oncol Biol Phys 2001;49:623–32.
6 Cheng JC, Chao KS, Low D. Comparison of intensity modulated radiation therapy (IMRT) treatment techniques for nasopharyngeal carcinoma. Int J Cancer 2001;96:126–31.
7 Xia P, Fu KK, Wong GW, Akazawa C, Verhey LJ. Comparison of treatment plans involving intensity-modulated radiotherapy for nasopharyngeal carcinoma. Int J Radiat Oncol Biol Phys 2000;48:329–37.
8 Dogan N, King S, Emami B, Mohideen N, Mirkovic N, Leybovich LB, et al. Assessment of different IMRT boost delivery methods on target coverage and normal-tissue sparing. Int J Radiat Oncol Biol Phys 2003;57:1480–91.
9 Wu Q, Mohan R, Morris M, Lauve A, Schmidt-Ullrich R. Simultaneous integrated boost intensity-modulated radiotherapy for locally advanced head-and-neck squamous cell carcinomas. I: dosimetric results. Int J Radiat Oncol Biol Phys 2003;56:573–85.
10 Lauve A, Morris M, Schmidt-Ullrich R, Wu Q, Mohan R, Abayomi O, et al. Simultaneous integrated boost intensity-modulated radiotherapy for locally advanced head-and-neck squamous cell carcinomas: II--clinical results. Int J Radiat Oncol Biol Phys 2004;60:374–87.
11 Niemierko A. Reporting and analyzing dose distributions: a concept of equivalent uniform dose. Med Phys 1997;24:103–10.
12 Sanchez-Nieto B, Nahum AE. BIOPLAN: software for the biological evaluation of. Radiotherapy treatment plans. Med Dosim 2000;25:71–6.
13 Suwinski R, Taylor JM, Withers HR. The effect of heterogeneity in tumor cell kinetics on radiation dose-response. An exploratory investigation of a plateau effect. Radiother Oncol 1999;50:57–66.
14 Jones B, Dale RG. Mathematical models of tumour and normal tissue response. Acta Oncol 1999;38:883–93.
15 Withers HR, Taylor JM, Maciejewski B. The hazard of accelerated tumor clonogen repopulation during radiotherapy. Acta Oncol 1988;27:131–46.
16 Burman C, Kutcher GJ, Emami B, Goitein M. Fitting of normal tissue tolerance data to an analytic function. Int J Radiat Oncol Biol Phys 1991;21:123–35.
17 Lee N, Xia P, Quivey JM, Sultanem K, Poon I, Akazawa C, et al. Intensity-modulated radiotherapy in the treatment of nasopharyngeal carcinoma: an update of the UCSF experience. Int J Radiat Oncol Biol Phys 2002;53:12–22.
18 Wolden SL, Chen WC, Pfister DG, Kraus DH, Berry SL, Zelefsky MJ. Intensity-modulated radiation therapy (IMRT) for nasopharynx cancer: update of the Memorial Sloan-Kettering experience. Int J Radiat Oncol Biol Phys 2006;64:57–62.
19 Kam MK, Teo PM, Chau RM, Cheung KY, Choi PH, Kwan WH, et al. Treatment of nasopharyngeal carcinoma with intensity-modulated radiotherapy: the Hong Kong experience. Int J Radiat Oncol Biol Phys 2004;60:1440–50.
20 Lee SW, Back GM, Yi BY, Choi EK, Ahn SD, Shin SS, et al. Preliminary results of a phase I/II study of simultaneous modulated accelerated radiotherapy for nondisseminated nasopharyngeal carcinoma. Int J Radiat Oncol Biol Phys 2006;65:152–60.
21 Eisbruch A, Ten Haken RK, Kim HM, Marsh LH, Ship JA. Dose, volume, and function relationships in parotid salivary glands following conformal and intensity-modulated irradiation of head and neck cancer. Int J Radiat Oncol Biol Phys 1999;45:577–87.
22 Eisbruch A, Ship JA, Dawson LA, Kim HM, Bradford CR, Terrell JE, et al. Salivary gland sparing and improved target irradiation by conformal and intensity modulated irradiation of head and neck cancer. World J Surg 2003;27:832–7.
23 Taheri-Kadkhoda z, Björk-Eriksson T, Johansson K-A, C. M. Long-term treatment results for nasopharyngeal carcinoma: the Sahlgrenska university hospital experience. Acta Oncol 2007;46:817–27.
24 Chen WC, Jackson A, Budnick AS, Pfister DG, Kraus DH, Hunt MA, et al. Sensorineural hearing loss in combined modality treatment of nasopharyngeal carcinoma. Cancer 2006;106:820–9.
25 Fang FM, Chiu HC, Kuo WR, Wang CJ, Leung SW, Chen HC, et al. Health-related quality of life for nasopharyngeal carcinoma patients with cancer-free survival after treatment. Int J Radiat Oncol Biol Phys 2002;53:959–68.
26 Amdur RJ, Li JG, Liu C, Hinerman RW, Mendenhall WM. Unnecessary laryngeal irradiation in the IMRT era. Head Neck 2004;26: 257–63.discussion 263–4
27 Longobardi B, De Martin E, Fiorino C, Dell'oca I, Broggi S, Cattaneo GM, et al. Comparing 3DCRT and inversely optimized IMRT planning for head and neck cancer: equivalence between step-and-shoot and sliding window techniques. Radiother Oncol 2005;77:148–56.
