Interstitial Brachytherapy with Ir-192 Low-Dose-Rate in the Treatment of Primary and Recurrent Cancer the Oral Cavity and Oropharynx

Abstract

To evaluate the impact of postoperative interstitial brachytherapy with and without external radiotherapy in the treatment of primary and recurrent squamous cell carcinoma of the oral cavity and oropharynx. Between 1985 and 1997, a total of 318 patients were treated by interstitial Ir-192 low-dose-rate brachytherapy as part of their primary (n = 236) or recurrent treatment (n = 82). There were 263 male (83%) and 55 (17%) female patients. The distribution of UICC (1997) stages was as follows: I (61 patients, 19%), II (71 patients, 22%), III (58 patients, 18%), IV (128 patients, 40%). The primary tumor site was located in the oral cavity in 201 patients (63%), in the oropharynx in 86 patients (27%), lower lip in 19 patients (6%) and other regions in twelve cases (4%). Treatment concepts did not vary over the time and were dictated by the initial tumor extension: a total of 175 patients (55%) received a combination of surgery, interstitial brachytherapy (23-25 Gy) and external radiotherapy (50-60 Gy), 60 patients (19%) surgery and interstitial brachytherapy (45-55 Gy) alone. Advanced disease not amenable to primary surgery was either treated by radiochemotherapy and interstitial brachytherapy in 39 patients (12%) or a combination of interstitial brachytherapy, external radiotherapy and interstitial hyperthermia in 44 patients (14%). Overall survival rates following primary and recurrent treatment were 50 +/- 4% and 29 +/- 5%, respectively, at 5 years (p < 0.0001). A significant impact on overall survival rate was noted for UICC stage: patients in stage I/II had survival rates of 64 +/- 5% and 57 +/- 10%, respectively, while patients in stage III/IV had survival rates of 39 +/- 5% and 15 +/- 5%, respectively, at 5 years (p < 0.0001). In addition, grading (p = 0.01) and hemoglobin levels (p = 0.05) had a significant influence on overall survival. Local tumor control rates for all patients were 74 +/- 3% and 57 +/- 7% at 5 years following primary and recurrent treatment (p = 0.01), respectively. The 145 patients treated for primary disease by a uniform concept of surgery, interstitial brachytherapy and external radiotherapy achieved excellent local control rates with 92 +/- 4% (stage I/II) and 65 +/- 6% (stage III/IV) at 5 years. Late treatment-related toxicity with soft tissue necrosis and/or osteonecrosis requiring mandibular resection was 7.5%. Local tumor excision followed by postoperative interstitial brachytherapy with and without external radiotherapy is associated with excellent locoregional control, a low risk of chronic sequelae and may therefore considered as a new approach avoiding mutilating radical surgery.