Interstitial brachytherapy for lip carcinomas: Comparison between Ir-192 low-dose-rate and high-dose-rate treatment

Low-dose-rate (LDR) and high-dose-rate (HDR) interstitial brachytherapy are known to be effective in the treatment of lip carcinomas. The aim of this study was to retrospectively compare oncologic and toxicity outcomes between the two techniques.

From 2007 to 2018, patients at the Institut de cancérologie de Lorraine (France) who received exclusive or adjuvant interstitial brachytherapy for lip squamous carcinomas were studied. Two groups were defined: the LDR/PDR group, including patients treated with iridium-192 wires, or pulsed-dose rate technique, and the high-dose-rate group, with patients treated by high-dose-rate technique. The dose ranged between 50Gy and 65Gy (depending on previous surgery) for low-dose-/pulsed-dose rate treatments, and 39Gy for high-dose-rate (twice a day). Early, late toxicity events and oncologic control were reported.

Among the 61 patients whose data were analyzed retrospectively, 36 received the low-dose-/pulsed-dose rate treatment (59%) and 25 the high-dose-rate brachytherapy (41%). The median follow-up time was 44 months. At 36 months, the local control rates were 96.3% for LDR/PDR group and 100% for HDR (P=0.180). The regional control rates were 85.9% and 92% without any difference according to the two groups (P=0.179). The specific overall survival rate was 95.5% with no difference between groups. There were more grade 2 or higher mucositis in the HDR group than in LDR/PDR group (40% versus 16.7%, P=0.042). One case of grade 3 mucositis was recorded in each group. No grade 3 late complications were recorded. High-dose-rate brachytherapy reduced the length of hospitalization by 2 days (P<0.001).

High-dose- or low-dose-/pulsed-dose rate brachytherapy seemed to be as effective and well tolerated in our experience of 61 patients.