Long Term Outcomes from LDR Brachytherapy in Treatment of Oral Tongue Cancer

Brachytherapy (BT) is a useful modality to decrease dose to normal tissue when used in the primary setting and offers the chance for salvage treatment in patients previously irradiated. For oral tongue cancer it can be used as stand-alone treatment or in combination with external beam radiation therapy (EBRT), surgery and/or chemotherapy. We review our 10-year experience with respect to outcomes and late toxicity. Between 1/04 and 12/14, 39 patients with oral tongue cancer received Ir-192 LDR BT as part of their treatment course. Patient characteristics were as follows: Median age 53 years (range 20 - 88); T-stage: 20T1:15T2:1T3:2T4:1multifocal, and N-stage: 26N0; 4N1; 4N2; 5Nx. Thirty one patients had primary (18T1: 10T2: 1 T3 and 2 T4) and 8 had recurrent disease (3T1, 4T2, 1 multifocal). The combination of EBRT+BT was prescribed for 20 patients, and 19 patients received BT alone. Eight patients were treated definitively with either EBRT+BT (n=6; T2N0, multifocal primary, T2N2b, T3N0, T4N1, T4N2c) or with BT alone (n=2; both T2N0). Thirty-one patients received adjuvant therapy either with EBRT+BT (n=14) or with BT alone (n=17). Indications for adjuvant EBRT+BT were elective nodal RT (n=3), LN+ (n=3), PNI (n=7) and recurrence (n=1). Indications for adjuvant BT alone included close/positive margin (n=11), PNI (n=2) or both close/positive + PNI (n=4). Among the 17 patients treated with adjuvant BT alone, 13 underwent elective neck node dissection (LND), while 4 did not. The median EBRT dose was 54Gy (30.6- 70Gy), and 1 patient received protons. The median BT dose in the EBRT+BT group was 20 Gy (10 - 27Gy). The median BT dose in the BT alone group was 45 Gy (30-60 Gy). The median number of catheters used was 4 (2 - 12). The catheters were positioned 5mm from the mandible, and oral lead shields were used during brachytherapy. Tracheostomy was performed in the majority of patients and 8 patients also had LND at the time of BT catheter placement. Nine patients in the EBRT + BT group received systemic therapy. The median follow up is 40.5 mo (7-118 mo). Overall, the 3-yr local control (LC), regional control (RC) and overall survival (OS) is 88%, 75.4%, and 83%, respectively. Among the definitively treated patients, the 3-yr LC, RC and OS is 100%, 85.7%, and 60%, respectively. Among the 14 patients treated with adjuvant EBRT+BT, the 3-yr LC, RC and OS is 91.7%, 78.8% and 100%, respectively. The 17 patients receiving adjuvant BT alone had a 3-yr LC, RC and OS is 82%, 67.3% and 84.6%, respectively. In this subset, patients undergoing LND had better RC compared to no LND (3-yr RC 84% vs 25%, p=0.017). Two patients experienced early (<6 mo) grade 3-4 toxicity; 1 osteoradionecrosis and 1 ulcer. The patient with early osteoradionecrosis had prior history of soft palate ca treated with cisplatin + 70Gy EBRT, and the second primary oral tongue ca in the prior RT field was treated with 36Gy protons + 27 Gy BT. Three patients experienced late (>6 mo) grade 3-4 toxicity. The patient with delayed osteoradionecrosis received a dose of 50Gy BT alone using 8 catheters. Two patients presented with delayed ulcer in the FOM/tongue. One patient received EBRT+BT using 12 catheters, and the 2nd patient received 60Gy BT alone. Therefore, suggesting that large volume implants and/or high BT dose may increase the risk of late toxicity. Oral tongue BT can be used to deliver highly individualized and conformal therapy, as definitive or adjuvant treatment delivered either as a boost or stand-alone therapy. High local control rates can be achieved in patients with positive margins with BT alone. LND is important to maintain high levels of regional control particularly in those receiving BT alone.