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  • br Conclusions Complete resection without positive surgical margins is

    2022-04-29


    Conclusions: Complete resection without positive surgical margins is essential for the treatment of the patients with T1 and T2 ear cancers. Prophylactic superficial parotidectomy or neck dissection is not mandatory for T1 and T2 diseases, as long as precisely extent of disease is assessed preoperatively. PORT should be performed for the patients with positive surgical margins. Levels of evidence: 4.
    1. Introduction
    Squamous cell carcinoma of the external auditory canal (EAC) is extremely rare with an annual incidence estimated at between 1 to 6 cases per million of the populations [1]. For early
    $ This research is partially supported by the grant from Japan Agency for Medical Research and Development (Grant#:17ck0106223h0002).
    $$ None of authors report any conflict of interest related to this SPDP manuscript.
    * Corresponding author at: Department of Otolaryngology-Head and Neck Surgery, Kobe University Graduate School of Medicine.7-5-1 Kusunoki-Cho, Chuo-Ku, Hyogo Kobe, 650-0017, Japan.
    E-mail address: [email protected] (H. Shinomiya). 
    stages T1 and T2, as defined by the modified Pittsburgh staging system [2], sleeve SPDP resection of the external canal or en bloc lateral temporal bone resection (LTBR), have yielded favorable oncological and functional results and are the treatment of choice at most institutions [3–5]. According to the United Kingdom National Multidisciplinary Guidelines published in 2016 [6], LTBR is regarded as the minimum oncologic operation for T1 and T2 lesions. Prophylactic superficial or total parotidectomy is recommended for all resections. Post-operative radiotherapy (RT) or chemoradiotherapy (CRT) is recommended for most T2-T4 disease, with the exception of T1 and selected T2 without particularly peri-neural infiltration and with clear margins. However, these guidelines were based on
    small number reports, and the indication of parotidectomy and postoperative radiotherapy (PORT) for T1 and T2 patients is not clearly determined at present. The purpose of this study was to clarify the impact of superficial parotidectomy and postoperative radiotherapy (PORT) for the surgical treatment of early EAC cancer.
    2. Materials and methods
    Between 2000 and 2016, 99 consecutive patients with squamous cell carcinoma arising from external auditory canal were treated at Kobe University Hospital. Among them, 37 patients with T1 or T2 tumor were enrolled in this study. All patients were pathologically diagnosed as having squamous cell carcinoma of the external auditory canal. At the initial diagnosis, extent of disease was assessed with the aid of contrast computerized tomography (CT) scan, magnetic resonance imaging (MRI), and 18-fluoro-2-deoxyglucose positron emis-sion tomography (FDG-PET). Diseases were staged according to the most recent version of the modified Pittsburgh classification (2000) [2].
    Thirty-three patients were surgically treated with sleeve resection or lateral temporal bone resection (LTBR). The other 4 patients were treated with radiotherapy (n = 3) or proton beam therapy (n = 1), due topatient’s refusal ortophysical condition and co-existing diseases. Postoperative RTwas employedin surgically treated patients only whose surgical margin was positive. Patients with close to margin (<3 mm), peri-neural invasion, or bone invasion were only observed carefully without PORT.
    We describe the indication of resection for T1 EAC cancer. Only if a tumor located in a limited area of EAC and a whole tumor was observable with appropriate surgical margins, we preformed sleeve resection. We performed LTBR, when the tumor didn’t meet the above conditions.
    For LTBR, the bony external auditory canal, tympanic membrane, malleus and incus were resected with extended mastoidectomy in an en bloc manner. The superficial lobe of the parotid gland was prophylactically resected in most T2 cases and the facial nerve was preserved in all cases. For T1 patients, if the tumor existed mainly in an anterior-inferior canal wall, we preferably resected a superficial lobe of parotid gland. LN metastases were not clinically observed in neck or parotid gland in any patient. Thus, no patients underwent prophylactic neck dissection.
    Medical records were retrospectively reviewed to obtain information concerning characteristics of the patients, extent of disease, surgical procedures including parotidectomy, metasta-sis of parotid LN, PORT, and oncological results. Kaplan-Meier plots were used to summarize time to event measured from the end of the first treatment. R software (Ver. 3.0.2. 2013. The R foundation for Statistical Computing, Vienna, Austria) was used for the statistical analysis. This study was approved by Kobe University Hospital Internal Review Board.