Interstitial brachytherapy with Ir-192 low-dose-rate in the treatment of primary and recurrent cancer of the oral cavity and oropharynx - Review of 318 patients treated between 1985 and 1997

Aim: To evaluate the impact of postoperative interstitial brachytherapy wit h and without external radiotherapy in the treatment of primary and recurre nt squamous cell carcinoma of the oral cavity and oropharynx. Patients and Methods: Between 1985 and 1997, a total of 318 patients were t reated 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, 1 8%), 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%), lowe r 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) alon e. Advanced disease not amenable to primary surgery was either treated by r adiochemotherapy and interstitial brachytherapy in 39 patients (12%) or a c ombination of interstitial brachytherapy, external radiotherapy and interst itial hyperthermia in 44 patients (14%). Results: Overall survival rates following primary and recurrent treatment w ere 50 +/- 4% and 29 +/- 5%, respectively, at 5 years (p < 0.0001). A signi ficant impact on overall survival rate was noted for UICC stage: patients i n 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) a nd hemoglobin Levels (p = 0.05) had a significant influence on overall surv ival. Local tumor control rates for all patients were 74 +/- 3% and 57 +/- 7% at 5 years following primary and recurrent treatment (p = 0.01), respect ively. The 145 patients treated for primary disease by a uniform concept of surgery, interstitial brachytherapy and external radiotherapy achieved exc ellent 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 necro sis and/or osteonecrosis requiring mandibular resection was 7.5%. Conclusion: Local tumor excision followed by postoperative interstitial bra chytherapy with and without external radiotherapy is associated with excell ent locoregional control, a low risk of chronic sequelae and may therefore considered as a new approach avoiding mutilating radical surgery.