14 Nasopharynx Cancer

Nasopharynx Cancer

18

THE GEC ESTROHANDBOOKOF BRACHYTHERAPY | Part II Clinical Practice Version 1 - 10/09/2019

Kwong (2000)

61 First LR, 53 Second LR, 8

NP confined

Split-palate implantation ISBT Au198 61Gy LDR

61Gy

5-year LC First LR: 62.7% Second LR: 23.4% 5-year OS: First LR: 53.6% Second LR: 42.9% 5-year LC: 89.3% 5-year OS: 65.2%

For entire cohort of persistent and recurrent disease Headache, 28% Palatal fistula, 19% NPUN, 16% TLN, 7%

10

Law (2002)

78

T1-T2a

Endoscopic pharyngeal recess dissection and tumor debulking ICBT 50-55Gy LDR

50-55Gy

5-year major compl-free rate: 47%

10

F, fractions; ICBT, intracavitary brachytherapy; ISBT, interstitial brachytherapy; ΣEQD2, cumulative dose equivalent in 2Gy; LR, local recurrence; LRFS, local recurrence free survival; LC, local control; CSS, cancer-specific survival; OS, overall survival; NPUN, nasopharyngeal ulceration or necrosis; CNP, cranial neuropathy; TLN, temporal lobe necrosis.

2014]. However, the poor outcomes in both arms, which are inferior in comparison to those of other published series, suggest suboptimal 2D EBRT techniques, which cannot be overcome by the addition of ICBT boost. On the other hand, a recent study examining the dose escalation using ICBT, after CRT using IMRT techniques, with or without adjuvant chemotherapy, among patients with T1-T3 tumours that have completely responded to IMRT, showed improved LC in T1 tumours with no increase in toxicity [Chao, 2017], supporting the benefit of dose-escalation even in the era of IMRT and CRT (Table 6). On the other hand, dose-escalation using IMRT techniques exclusively in the setting of CRT is associated with increased toxicity [Teo, 2000; Lin, 2004; Wolden, 2001], underscoring the fact that the highly localized and conformal doses attainable with ICBT are difficult to achieve with IMRT techniques. For T1 and T2 recurrent or persistent disease, ICBT, alone or in combination with EBRT, is particularly useful in due to stringent OAR dose limitations (Table 7). Two retrospective studies reported 5-year LC and OS rates of 61-63% and 40-50%, respectively, with brachytherapy alone [Kwong, 2001; Choy, 1993]. Inferior outcomes (5-year locoregional failure and OS rates of 45-88% and 28-40%, respectively) with either ISBT [Syed 2000] or ICBT [Cheah, 2014] boost have been reported, possibly relating to more advanced local recurrences. Major complication rates were still significant, reported in 35-45% of patients. On the other hand, a retrospective comparison of EBRT alone (median dose, 59 Gy) vs EBRT (median dose, 45 Gy) with ICBT boost (20 Gy LDR) showed similar LC, event-free survival, and OS rates (52%, 44%, 60%) but lower grade 3 toxicities (73% vs 8%) with ICBT boost [Koutcher, 2010].

Nasopharyngeal mucosal ulceration and necrosis rates of up to 6% have been reported with ICBT using 2D techniques. A lower rate may be expected with the use of 3D techniques and modern fractionation (3-4 Gy twice-daily). An 18% rate has been reported with the use of hybrid ICBT/ISBT technique [Ren, 2010]. Soft palate atrophy, fistulization and velopharyngeal insufficiency are reported primarily in salvage brachytherapy series, particuarly with split-palate approaches, for which rates of 16-19% have been reported. Osteoradionecrosis (ORN) of the cervical vertebra, specifically the atlantoaxial joint, is a late toxicity that is particularly attributed to brachytherapy and occur mostly after re-irradiation with brachytherapy for recurrent disease [Tiruchelvarayan, 2012; King, 2010]. Moreover, in case of cervical vertebral ORN, brachytherapy re-irradiation was found to be a significant predictor for the need for surgical intervention in both univariate and multivariate analyses [Huang, 2018].

13. ADVERSE SIDE EFFECTS

Sinus headache is common during ICBT and can be alleviated with analgesics, regular irrigation and suctioning of nasal secretions, and instillation of local anesthetics if necessary. More significant headache may be associated salvage brachytherapy, particularly with the use of LDR seed implants.