13 Oropharynx

Oropharynx 285

five-year local control rate was better for T1-2 tumours than for T3 tumours (87% versus 67%, p = 0.00004). The prognosis of tumours extending to the mobile tongue or base of tongue was worst ( p < 0.002). For maximising local control, the authors recommended that the total duration of the treatment should be less than 55 days. The number of days between external beam irradiation and brachytherapy should be less than 20, and the security margin around the gross disease more than 5 mm large. Similar results were achieved at the Henri Mondor Hospital where 165 T1 - 2 squamous cell carcinomas of the faucial arch were treated with irradiation with external beam irradiation, interstitial implantation, or external beam irradiation followed by an interstitial implantation (13). Five- year local control rates were 58%, 100%, and 91%, and five-year overall survival rates 21%, 50.5%, and 60%, respectively. The best local control rate was achieved with a combination of external beam irradiation and brachytherapy using the plastic tube technique described above (94% at 5 years); the probability of minor or moderate necrosis was 20%. A local control rate of 92% was obtained in the Gustave Roussy institute in a population of 53 patients treated with a combination of 50 Gy external beam irradiation and of 20 - 35 Gy interstitial brachytherapy for a limited carcinoma of the soft palate and uvula (3). We recommend that T1 - 2 (and some limited T3) tumours of the faucial arch should be treated with 45 - 50 Gy radiation or chemoradiation followed as soon as possible by a 20 - 25 Gy interstitial boost. For node positive patients, a 20 - 30 Gy electron boost should be added to the involved nodes or a neck dissection performed. We can expect in T1 - 2 tumour patients, a local control rate of about 90%, a 5-year overall survival rate of about 60%, with the occurrence of a temporary late necrosis of the mucosa in about 20% of cases (3,13,15). The above-cited results were achieved using low dose rate technique. Results obtained with a combined external beam and fractionated high dose rate or pulse dose rate brachytherapy boost are preliminary. Some results are now available with high dose-rate brachytherapy, and look comparable to those achieved with low dose-rate brachytherapy (Table 12.2). Results obtained at 3 years in a population 38 T1 - 4 squamous cell carcinomas of the tonsillar region and soft palate with fractionated high dose rate or pulsed dose rate regimens by Levendag et al. also look similar to those obtained with low dose rate techniques (10). Interstitial implantations may also play a special role for salvage treatment. It can be successfully carried out for treating tumours arising or recurring in previously irradiated areas (7,12,14). The five- year local control rate was 57 - 69%, five-year overall survival rate 14 - 30%, and necrosis rate 11 - 27%.

Table 12.1: Local control and complication rates obtained with combined external beam irradiation and brachytherapy boost in carcinomas of base of tongue.

Authors

Local control rate

Complication rate

T1

T2

T3

T4

Crook et al. (1) Hoffsteitter et al. (6) Horwitz et al. (7) Housset et al. (8) Lusinchi et al. (11) Puthawala et al. (16)

85% 71% 86% 69%

12/48 14/72 4/20 3/29 29/108 10/70

64%

10/11

8/9

6/6

74%

83% 51%

69%

2/2

88%

75% 67%