Sun Yat-sen Memorial Hospital, Sun Yat-sen University

1. Introduction:

Hypopharyngeal cancer is a common malignant tumor of the head and neck, ranking 27th in the world in 2020. Current treatments for hypopharyngeal carcinoma include surgical resection plus postoperative adjuvant radiotherapy (SRT) and concurrent radiochemotherapy (CRT). Hypopharyngeal cancer often invades the larynx, and both surgery and radiotherapy can cause laryngeal insufficiency and affect the quality of life of patients. Repair of laryngeal and hypopharyngeal defects after surgical resection of hypopharyngeal carcinoma includes pull-in suture, adjacent tissue flap or free flap repair. The submental artery island flap (SMAIF) is located in the same surgical field as hypopharyngeal carcinoma resection, and the thickness of the flap is suitable, which has the advantages of convenient harvest, stable blood supply and high accessibility. The SMAIF was used to repair the hypopharynx, but the laryngeal defeat was ignored. This study is a prospective single-arm study, which is aimed to assess the safety and efficacy of SMAIF to repair the laryngeal and hypopharyngeal defects of the resection of T2-T3 hypopharyngeal carcinoma. The oncological results and laryngeal function parameters will be recorded. The ultimate gold of the study is to obtain a simple and effective reconstruction method for locally advanced hypopharyngeal cancer. 2. Background:

Hypopharyngeal squamous cell cancer (HPSCC) is a common head and neck malignant tumor, ranking 27th among new malignant tumors in the world in 2020 [1]. HPSCC has an insidious onset, is prone to submucosal infiltration and growth, and cervical lymph node metastasis occurs in the early stage. When discovered, most are in the late stage, and have the worst prognosis among head and neck squamous cell carcinomas. Surgery plus postoperative radiotherapy (SRT) or radical concurrent chemoradiotherapy (CRT) is the mainstream treatment for HPSCC [2]. The 5-year overall survival rate of the SRT group was 44.6%, while that of the CRT group was 40.4%. SRT has a better 5-year survival rate than CRT (HR=0.89) [3]. HPSCC often invades the larynx. Regardless of surgery or radiotherapy, it can cause cricoarytenoid joint impairment, laryngeal cartilage necrosis and other laryngeal injuries after treatment, followed by dyspnea, dysphagia and other laryngeal insufficiency, which requires long-term tracheotomy or with a gastric tube affects the patient's quality of life.

Of the SRT group, due to the different proportions of total laryngectomy and different repair methods among different hospitals, the laryngeal function preservation rate among the SRT groups varies greatly [3]. Among them, Jang et al. reported the largest surgical sample size (n=177), with a higher proportion of larynx-preserving surgery. The reported larynx-preserving rate (LPR) after hypopharyngeal cancer surgery was about 60%, but it was still inferior to the 76.6% of CRT [4]. The inclusion criteria of Jang and others are relatively consistent with the preset inclusion conditions of this clinical trial, so we selected Jang's LPR as the baseline. Reconstruction of laryngeal and hypopharyngeal defects after surgical resection of HPSCC include pulling-in suture, adjacent tissue flap or free skin flap repair [5]. T3 hypopharyngeal cancer cases often invade the ipsilateral paraglottic space and require resection of the ipsilateral hemi-larynx. Therefore, simultaneous repair of hemi-laryngeal defect and hypopharyngeal defect remain a challenge for the surgeons.

In the early stage, we used adjacent platysma muscle flap transfer to repair defects of the larynx and hypopharynx, and achieved satisfactory results [6]. However, the platysma flap has no definite perforating arteries and the size of the donor is limited. At the same time, the platysma flap tissue volume is small, making it difficult for the hypopharyngeal piriform sinus to reach normal size after repair. We also used the radial forearm perforator flap (RFPF) to repair posterior pharyngeal wall defects during resection of HPSCC [7]. However, free flaps require microvascular anastomosis, which is technically difficult, risky, and time-consuming. It often requires two groups of surgeons, tumor resection and reconstruction, to perform the surgery at the same time. These factors also limit the use of free flaps for repair after hypopharyngeal cancer resection.