Patterns of feeding tube utilization in base of tongue adenoid cystic carcinoma treated with neutron radiotherapy.

Abstract

e18074 Background: For locally advanced salivary cancers, primary radiotherapy is an option for unresectable disease or when resection would cause significant morbidity. Surgery for locally advanced base of tongue (BOT) adenoid cystic carcinoma (ACC) is rarely curative and often results in permanent feeding tube dependence. Neutron radiotherapy (NRT) provides locoregional control in many patients, but data on long-term swallowing outcomes is limited. We examine patterns of feeding tube utilization after NRT for BOT ACC. Methods: Retrospective, single-institution study of BOT ACC patients ≥18 years treated with primary NRT or NRT for locoregional control (LRC) in M1 disease from 1992 to 2023. Baseline characteristics and complications were abstracted, including short and long-term (≥90 days) use of percutaneous endoscopic gastrotomy (PEG) tubes. LRC was calculated using Kaplan-Meier method. Results: 51 patients with cT3-T4 BOT ACC treated with NRT were identified. Prophylactic PEG was advised per institutional practice. 34 (67%) had PEG placed prophylactically prior to NRT, and 4 (8%) reactively due to treatment effects. Of evaluable patients (n=45), median LRC was 5.1 years (95%CI 3.0-NR). At last follow-up (median 2.4 yrs, living patients, range 1 mo-15 yrs), 27 had LRC and 18 had locoregional failure. At 90 days post-NRT, 35 patients were evaluable for utilization of PEG placed at time of treatment, and 7 had ongoing PEG use. At 6 mos, 3 had ongoing PEG use, and only one continued to have PEG use until last follow-up (39 mos). New late post-NRT PEG was placed in 12 patients, of whom 10 had history of prior PEG. 3 were placed due to post-NRT dysphagia, median 42 mos after NRT (range 4-48mos); all 3 retained the PEG until last follow-up (median 9 mos after placement). 9 required PEG due to disease progression/salvage therapy, median 71 mos after NRT (range 35-105mo); of whom 8 retained the PEG until last follow-up (median 13 mos after placement), while 1 had PEG removed after 2 mos. One patient required esophageal dilation for stricture 10 years after NRT. Conclusions: There is limited reported data on swallowing outcomes of patients with BOT ACC treated with primary RT. In this treatment refractory disease, NRT is a viable option for BOT ACC and provides organ preservation as an alternative to glossectomy in patients with locally advanced tumors and significant rates of LRC. Functional outcomes after NRT were favorable, and most patients regained oral independence. A minority of patients had subsequent PEG placed, mostly in those with disease progression or undergoing salvage local therapy. Cohort and PEG use (n=51). Characteristic n (%) or other Age, years, median (range) 61.0 (25-84) Female 32 (62.7) Out-of-state 46 (90.2) T stage  3 13 (25.5)  4 38 (74.5)  M1 12 (23.5) Clinical stage  III 11 (21.6)  Iva-c 40 (78.4)  New PEG ≥ 90 days after NRT (n=35) 12 (34.3)