Interstitial Brachytherapy for Locally Advanced Tongue Cancer: Analysis of the Long-Term Treatment Results for Survival and Complications.

Abstract

PURPOSE/OBJECTIVE(S)\nThe purpose of this study was to evaluate the long-term treatment results of interstitial brachytherapy (IBT) in patients with locally advanced tongue cancer.\n\n\nMATERIALS/METHODS\nbetween 1994 and 2015, 60 patients (18 females and 42 males) with locally advanced tongue cancer treated by IBT using Ir-192 sources and Au-198 seeds were analyzed. The median age was 63 years (range, 22-86 years). All histological type was squamous cell carcinoma. T3/T4a/T4b was noted in 51/9/0 patients, respectively. The median depth of invasion was 11 mm (3-27 mm). The growth type was infiltrative/exophytic/superficiality in 54/0/6 patients, respectively. In all cases, no lymph node metastasis was not found at diagnosis. IBT was performed using Ir-192 in 56 patients and Au-198 in 4 patients. Median irradiation doses of Ir-192 and Au-198 were 60 Gy (29-77 Gy) and 68 Gy (64-73 Gy), respectively. External beam radiation therapy (EBRT) was performed before IBT in 41 patients (68%). Median dose of EBRT was 30 Gy (30-50 Gy). Chemotherapy was combined with IBT in 42 patients.\n\n\nRESULTS\nMedian follow-up time for survivors was 103 months (36-230 months). CR rate was 98%. The 10-year overall/cause specific survival (OS, CSS) rate was 67/84%, respectively. According to T factors, the 10-year OS/CSS rates for T3 and T4a were 64/85% and 77/77%, respectively. There was no significant difference in OS and CSS between T3 and T4a. The10-year local/regional control rates were 78/72%, respectively. The 75% of the regional metastasis was occurred within 1 year, and more than 90% was within 2 years. The 10-year local control rates for T3 and T4a were 75% and 88%, respectively. The 10-year regional control rates for T3 and T4a were 71% and 77%, respectively. There was no significant difference in local/regional control between T3 and T4a. In the multivariate analysis, significant differences in OS were seen with elderly age, patients having double cancer and having late regional lymph node recurrence. According to CTCAE ver. 5.0, grade 2 soft tissue complications were observed in 33 (55%) patients and grade 2 mandibular complications in 2 (3%) patients. There were no grade 3 or more late complications.\n\n\nCONCLUSION\nOur 10-year treatment results of IBT for locally advanced tongue cancer showed favorable survival and low occurrence rate in patients with severe late complications.