14 Nasopharynx Cancer

Nasopharynx Cancer

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

Table 8. Brachytherapy (BT) as boost to External Beam Radiotherapy (EBRT): Chemoradiation Era Study Number of patients (Boost: No boost) Patient Age T- and N- Stage RT course ΣEQD2

Local Control and Survival

Toxicity

Randomized Controlled Trial Rosenblatt (2014) 274 (135:139)

Boost: 40 ±14.8 No boost: 43.5 ±13.6

Boost T3-4N2-3: 26.7% No boost T3-4N2-3: 24.5%

EBRT (2D): 70Gy/35F

Boost: HDR: 112.8Gy 10 LDR: 81Gy 10 No boost: 70Gy 10

3-year LRFS Boost: 54.4% No boost: 60.5% P=0.647

Any G 3-4 late toxicity Boost: 24% No boost: 22%

BT (2D ICBT): HDR: 27Gy/3F LDR: 11Gy

Rx pt: Tumor tissue point, TT; Levendag system

3-year OS Boost: 63.3% No boost: 62.9% P=0.742

Retrospective cohort Chao (2017)

232 (124:108)

Boost: >50 (49%) No boost: >50 (51%)

Boost: T1–2, 88% T3, 12% N0-1, 65% N2-3, 35% No boost: T1-2, 83% T3, 17% N0-1, 57% N2-3, 31%

EBRT (IMRT): 70Gy/35F

Boost: 86Gy

5-year LC Boost: 94.3% No boost: 88.7% P=0.228

10

No boost: 70Gy 10

BT (2D/3D ICBT): 12Gy/2F Rx pt: 3-5mm beneath balloon surface (2D); 90% of CTV (3D)

F, fractions; 2D, two-dimensional; ICBT, intracavitary brachytherapy; Rx pt, prescription point; CAX, central axis; ΣEQD2, cumulative dose equivalent in 2Gy; IMRT, intensity-modulated radiotherapy; LRFS, local recurrence free survival; LC, local control; OS, overall survival.

12. RESULTS

Benavides Cancer Institute Approach Given the scarcity of literature on nasopharyngeal IGBT, we have devised our protocols based on our current IMRT protocols and on published 2D and LDR BT protocols, and modifying the BT fractionation based on GEC-ESTRO guidelines for HDR BT for head-and-neck cancers [Mazeron, 2009], resulting in cumulative doses as detailed in Tables 5 and 6.

A significant RT dose-response relationship was observed in retrospective studies among patients treated with 2D EBRT techniques, with better local control (LC) among patients treated to ≥70 Gy [Mesic, 1981; Perez, 1992]. A total dose of 77-81 Gy has been recommended if treating with RT alone [Levendag, 2002]. In the pre-chemoradiation era, several retrospective cohorts showed that for T1-T2 disease, dose escalation by ICBT [Chang, 1996; Teo, 2000; Leung, 2008; Wu, 2013], as well as ISBT [Ren, 2010], after EBRT has led not only to improved LC, but also survival, with similar or decreased toxicity (Table 5). On the other hand, a retrospective cohort that included both T1-2 and T3-4 disease found similar LC and survival rates with the addition of ICBT boost [Ozyar, 2002], suggesting the ineffectiveness of ICBT in more advanced T disease. In the chemoradiation era, excellent local control rates (up to 85.8% overall 8-year local failure free survival; T1: 91.7%, T2: 88.2%, T3: 87.2%; T4, 71.6%) have been achieved leading to a decline in ICBT use [Au, 2018; Lee, 2015]. For stage III and IV disease, a multi-center trial examining dose escalation by ICBT after neoadjuvant chemotherapy and concurrent CRT did not demonstrate significantly improved outcomes, including LC for T1-T2 tumours, compared to the latter regimen alone [Rosenblatt,

11. MONITORING

During the few days of the application, the patients receive sedatives and a liquid or pureed diet. Headache may occur but a correctly made applicator remains well positioned and does not interfere with sleep. It is very important to check the applicator position, clinically or radiologically, and to suction the secretions, which accumulate at the nares, several times daily.