High dose rate brachytherapy for lip cancer with interstitial, surface, or a combination of interstitial and surface mold technique.

Purpose: High-dose-rate brachytherapy (HDR-BT) is now becoming more common than low-dose-rate and pulsed-dose-rate BT in the treatment of lip cancer. However, due to the limited history of HDR-BT, relatively few studies have been published. Two institutions (in Ukraine and the USA) reviewed their clinical outcomes of lip cancer patients treated with HDR-BT as monotherapy or in combination with external beam radiotherapy (EBRT).

Methods and materials: An interstitial (IS), surface custom mold (SC), or a combination of IS and SC (IS+SC) was used for treatments based on the depth of tumor invasion. Prescription doses were 24 Gy in 6 BID fractions when combined with 46-50 Gy of EBRT, 45-55 Gy in 9-10 BID fractions for IS and IS+SC monotherapy or 3 Gy × 16 daily fractions for SC monotherapy.

Results: A total of 33 cases of lip cancer were treated from 2015 to 2021. By using TNM staging classification, there were 14 stage I (42.4%), 15 stage II (45.5%), and 4 stage III (12.1%) lip cancers. Thirty-one patients (93.9%) had a complete response to the treatment. Only 2 patients (6.1%) displayed local recurrence. Grade 1, 2, and 3 acute toxicities were observed in 30.3%, 51.5%, and 18.2% of patients, respectively. Grade 1, 2, and 3 late toxicities were observed in 39.4%, 21.2%, and 0.0% of cases. Cosmetic results were excellent in 21.2%, good in 54.5%, fair in 18.2%, and poor in 6.1% of patients.

Conclusions: HDR-BT is an effective and safe treatment for lip carcinomas with excellent local control, functional, and cosmetic outcomes and should be considered as a standard treatment.