Phase I/II study on kilovoltage surface brachytherapy in conjunctival cancer: preliminary results

Abstract

IntroductionIn ocular conjunctival carcinoma after surgery, adjuvant treatment has a role and kilovoltage surface brachytherapy opens a new door for the range of therapeutic options.Materials and methodsBetween October 2014 and June 2017, at the National Institute of Neoplastic Diseases (INEN) from Peru, 39 patients with squamous cell carcinoma of ocular conjunctiva, T1–T3, resected, were selected to receive adjuvant treatment. The portable accelerator of 50-kV INTRABEAM (Carl Zeiss Meditec) was used, after local anaesthesia and blocking of ocular muscles movement. The doses used were 18 Gy for patients with free margins and 22 Gy for positive edges, according to calculation of equivalent dose of 2Gy per fraction of 46 and 66 Gy, respectively, assuming a tumoural α/β ratio of 8 Gy. The prescription was done to 2 mm depth.ResultsThe median age was 69 years, distributed evenly between both genders, with a median follow-up of 12 months. The surgical margins were 59% free and 41% committed, with no difference between the institutions where the surgery was performed (P = 0.069). The median tumour size was 7 mm with 2 mm of invasion, 61.5% was T2 and 35.9% T1. The mean time between surgery and irradiation was 1.5 months, 23.1% of patients developed grade I toxicity of spontaneous resolution, without evidence of greater degree in any case. The dose had no statistical relationship with toxicity (P = 0.533). One-year disease-free survival was 96.7%.ConclusionsKilovoltage surface brachytherapy is an applicable and reproducible tool in the treatment of squamous cell carcinoma of ocular conjunctiva. The administered doses are well tolerated by patients with low levels of acute toxicity. Longer follow-up is needed to establish disease control rates and late toxicities.

Single-Fraction Adjuvant Electronic Brachytherapy after Resection of Conjunctival Carcinoma

“…To our knowledge, we are the first group worldwide to report the outcomes of e-BT in this scenario. In addition to a previous publication regarding treatment safety and toxicity profile [ 23 ], these current results highlight the value of this approach, in matters of toxicity, disease control, and logistic advantage. The latter feature yields a special benefit, as high influx facilities struggle permanently in matters of extended waiting lists for EBRT slots [ 24 ].…”

Single-fraction low-energy electronic brachytherapy for conjunctival lymphoma

“…In consequence, we initiated a phase I/II study on adjuvant electronic brachytherapy for patients with resected squamous cell carcinoma of the ocular conjunctiva. At single doses between 18 and 22 Gy, we did not see any grade 2 or higher toxicity, which suggested that this therapeutic strategy may also be safe for patients with conjunctival lymphomas, where even lower doses were applied [ 34 ].…”