Familial Nasopharyngeal Carcinoma 6

Management of Patients with Failure Following Definitive Radiation Therapy 247Table 19.4. Results in literature on external beam reirradiation for local failure of carcinoma of the nasopharynxStudyNo. ofpatientsRadiationtechniqueTreatment outcomeCumulative incidence ofmajor late complications5-yearLocal control (%)5-yearSurvival (%)Any (%)Brainnecrosis(%)Teo et al. (1998) 123 2D RT rT1: 43rT2: 31rT3–4: 16rT1: 63rT2: 48rT3–4: 31– 20Lee et al. (1997) 654 2D RT rT1: 35rT2: 28rT3–4: 1116 26 3Wang (1987) 51 2D RT – 33 6 2Pryzant et al. (1992) 53 2D RT 35 18 – –Yan et al. (1983) 219 2D RT – 18 >29 >12Chua et al. (1998) 97 2D RT – rT1–2: 57rT3: 42rT4: 17– 16Leung et al. (2000) 91 2D RT 38 30 57 27Chang et al. (2000) 186 2D RT (81%)3D CRT (19%)– rT1: 38.5(3-year)rT2: 23.7rT3: 28.4rT4: 3.72D RT: 233D CRT: 92D RT: 143D CRT: 0Zheng et al. (2005) 86 3D CRT rT1: 92rT2: 81rT3: 68rT4: 41rT1: 70rT2: 52rT3: 32rT4: 1044 16Lu et al. (2004) 49 IMRT 100 (9-month) – – –Chua et al. (2005a) 31 IMRT rT1–3: 100rT4: 35(1-year)63 19 72D RT 2D treatment planning and radiation therapy; 3D CRT 3D conformal radiation therapy; IMRT: Intensity-modulated radiationtherapyobserved a 5-year local control rate of 43% for rT1–3 diseaseand 27% for rT4 disease. Late complications includedcranial neuropathy in 32%, brain necrosis in 13%, softtissue and osteoradionecrosis in 6%, and carotidpseudoaneurysm in 3%. These results suggest goodlong-term control with a relatively low risk of latecomplications compared with other series using conventionaltechnique of reirradiation.The challenging issue in external beam reirradiationis to retreat the target volume to a high dose(>54 Gy) while minimizing dose to adjacent criticaltissues. Neurological tissues including optic apparatus,brain stem, temporal lobe and spinal cord usually representthe dose-limiting structures in treatment planning,and the dose constraint is usually set at 12%–20%of the prescription dose. In our experience, this is oftendifficult to achieve for advanced T stage recurrenceand bulky tumor even with the use of IMRT, and inductionchemotherapy is often used to improve target coverageand sparing of organs at risk. Newer techniquesof radiotherapy allow better sparing of normal tissuesand may further improve the outcome in locally recurrentNPC. Taheri-Kadkhoda et al. (2008) showedthat three-field intensity modulated proton therapy