Institutional Experience of Interstitial Brachytherapy for Head and Neck Cancer with a Comparison of High- and Low Dose Rate Practice

Aims: To describe our institutional experience with high dose rate (HDR) interstitial brachytherapy (IBT)compared with previously reported results on the low dose rate (LDR) practice for head and neck cancer.Materials and
Methods: Eighty-four patients with oral cavity (n=70) or oropharyngeal cancer (n=14) weretreated with 192Ir HDR-IBT. Seventy-eight patients had stage I or II tumour. The patients treated with IBTalone (n=42) received 39-42 Gy/10-14 fractions (median=40 Gy/10 fractions). With respect to the combinationtherapy group (n=42), prescription dose comprised of 12-18 Gy/3-6 fractions (median=15 Gy/5 fractions) forIBT and 40-50 Gy/20-25 fractions (median=50 Gy/25 fractions) for external radiotherapy. Brachytherapy wasgiven as 2 fractions per day 6 hours apart with 4 Gy per fraction for monotherapy and 3 Gy per fraction forcombination therapy.
Results: Four patients were not evaluable in the analysis of outcome. The primary siterelapse rates were 23.8% (10/42) and 68.4% (26/38) in patients treated with IBT alone and combination therapy,respectively (p<0.001). Salvage surgery was performed in 19 patients. The 5-year local control rate was estimatedat 62% and the disease-free survival (DFS) rate at 52% for all patients. Local control with respect to T1 and T2tumours was 84% and 42%, respectively.
Conclusions: Our present series on HDR-IBT and the previous reporton LDR-IBT for head and neck cancer demonstrated similar DFS rates at 5 years (52%). The rate of regionalfailure in node-negative patients was <20% in both of our series. HDR-IBT offers similar results to LDR-IBTfor head and neck cancer.