Abstract
External auditory canal cancer is an extremely rare disease entity, with an annual incidence of 1 per million populations. The main histopathological type is squamous cell carcinoma (SCC), accounting for up to 90% of cases, with adenoid-cystic carcinoma and adenocarcinoma accounting for the remaining cases. Due to the rarity of the disease and difficulty in surgical treatment arising from the complex anatomy of the temporal bone, no general consensus has been arrived yet on the optimal treatment protocol. In this manuscript, we discuss the short-term outcomes of the management for SCC of the external auditory canal, mainly by surgical resection, at our institution. A total of 35 cases, initially managed at our institute from July 2015 to April 2019, were enrolled. Of the 35 patients, 27 were treated primarily by surgery (including 18 cases of lateral temporal bone resections, 7 cases of subtotal temporal bone resections, and 2 cases of partial resections) (primary surgical treatment group). Non-surgical treatments consisted of CRT with TPF (n=6) (TPF-RT group). Analyses revealed no statistically significant difference of the overall survival (OS), disease-specific survival (DSS) of, disease-free survival (DFS) between the primary surgical treatment and TPF-RT groups. In the primary surgical treatment group, postoperative recurrences occurred relatively early, usually within a year of surgery. Also, none of the age, sex, surgical procedures employed, disease stage, and postoperative radiation therapy have any significant influence on the DFS in this group. On the other hand, positive surgical margin, determined by postoperative histopathology, was associated with significantly poorer outcomes. Patients with postoperative recurrence consisted of 2 cases who showed preoperative rapid progression, and 3 with recurrent neck lymph node metastasis. Among the cases with advanced disease also, no statistically significant differences in the outcomes were observed between the primary surgical treatment and TPF-RT groups. While surgical treatment was associated with relatively good outcomes, in these cases, the highly invasive nature of extended surgery supports the selection of TPF-RT for these cases. Further accumulation of cases and evaluation of the long-term outcomes will be expected to provide evidence to establish a standardized treatment protocol for SCC of the external auditory canal.
