Single-Fraction Adjuvant Electronic Brachytherapy after Resection of Conjunctival Carcinoma

A retrospective study was performed to assess the outcomes of a single-fraction adjuvant electronic brachytherapy (e-BT) approach for patients with squamous cell conjunctival carcinoma (SCCC). Forty-seven patients with T1-T3 SCCC were included. All patients underwent surgery followed by a single-fraction adjuvant e-BT with a porTable 50-kV device. Depending on margins, e-BT doses ranged between 18 to 22 Gy prescribed at 2 mm depth, resembling equivalent doses in 2 Gy (EQD2) per fraction of 46-66 Gy (α/β ratio of 8-10 Gy and a relative biological effect (RBE) of 1.3). The median age was 69 (29-87) years. Most tumors were T1 (40.4%) or T2 (57.5%) with a median size of 7 mm (1.5-20). Margins were positive in 40.4% of cases. The median time from surgery to e-BT was nine weeks (0-37). After a median follow-up of 24 (17-40) months, recurrence occurred in only two patients (6 and 7 months after e-BT), yielding a median disease-free survival (DFS) of 24 (6-40) months and DFS at two years of 95.7%. Acute grade 2 conjunctivitis occurred in 25.5%. E-BT is a safe and effective for SCCC treatment, with clinical and logistic advantages compared to classical methods. Longer follow-up and prospective assessment are warranted.