Supracricoid partial laryngectomy (SCPL) is a surgical technique used for en bloc resection of the thyroid cartilage, paraglottic space (PGS), and preepiglottic space (PES) with an oncological outcome comparable to a total laryngectomy [1,2]. SCPL is classified according to the type of reconstruction required after resection: cricohyoidoepiglottopexy (CHEP) for glottic carcinomas and cricohyoidopexy (CHP) for tumors with supraglottic components. The SCPL with CHP is an alternative to radiation therapy, supraglottic laryngectomy, and near total and total laryngectomy in selected cases of supraglottic and transglottic carcinoma. The indications for SCPL with CHP are: carcinoma of the supraglottis with involvement of the glottis and anterior commissure; ventricle and PGS invasion; marked limitation of vocal cord mobility; minimal thyroid cartilage invasion; and, glottic carcinoma with involvement of both vocal cords and the anterior commissure [2,3,4]. This procedure is a true organ preservation technique and should be considered as a conservative laryngeal technique since it preserves physiological rehabilitation of speech, swallowing and respiration without a permanent tracheostomy.

The PES was first described in the late 1700s by Boyer, who considered that the region functioned as a prethyrohyoid bursa [5]. It is separated from mucosal surfaces of the head and neck by the hyoepiglottic ligament superiorly, the thyrohyoid membrane anteriorly, and the anterior surface of the epiglottis and thyroepiglottic ligaments posteroinferiorly. These boundaries demarcate a relatively avascular, inverted pyramid-shaped space that contains lymphatics, fat, and loose areolar tissue [6,7]. Invasion of tumor into such a sequestered avascular space signifies advanced disease that may be difficult to eliminate by radiation therapy, which is in part dependent on adequate tissue oxygenation. Supraglottic infrahyoid carcinomas can easily involve the preepiglottic space by direct invasion through multiple fenestrations of the epiglottic cartilage or via the quadrangular membrane [8]. Ljumanovic et al. [9] reported that PES involvement in patients with supraglottic tumors is predictive of local recurrence in patients treated with definitive radiation therapy alone.

The purpose of this study was to analyze the PES invasion yield, and to determine the nature of the relationship between these tumors and cervical nodal metastases and consequent disease specific survival in patients undergoing SCPL with CHP.

The aim of SCPL is to achieve the same local control rates as with total laryngectomy while sparing the function of the larynx. Some authors showed that a probability of 5-year survival rate in patients with SCPL was 92.62% [11]. SCPL is an oncologically safe procedure to preserve laryngeal functions in selected patients with glottic and supraglottic carcinomas [12,13]. Laccourreye et al. [1,2] reported on SCPL as removing the PES, epiglottis and PGS, including thyroid cartilage. Depending on the degree of invasion of the tumor, both of the arytenoids can be spared or one of them can be removed. The reconstruction is immediately carried out by approximation of the cricoid cartilage to the hyoid by CHP, to form a neo-larynx. Thus natural respiration, phonation, deglutition, and sphincteric functions can be maintained without the necessity of a permanent tracheostoma [2,3]. In SCPL with CHP, the thyroid cartilage, the PGS, the PES, and the whole epiglottis are excised, whereas the hyoid bone, the cricoid cartilage, and one or two arytenoid cartilages are preserved.

The PES of the larynx is a loose areolar area composed of elastic and collagenous fibers and adipose tissue. Since the first description by Boyer, several authors have defined its extension [5,14]. The PES is surrounded by the hyoepiglottic ligament superiorly, by the thyrohyoid membrane and thyroid cartilage anteriorly, and by the thyroepiglottic ligament and epiglottic cartilage posteroinferiorly [14]. Overall, PES involvement is a relatively common occurrence in advanced squamous cell carcinoma of the head and neck, particularly in tumors arising from the supraglottis and the base of tongue. The PES is frequently involved with tumor, probably because the elastic epiglottis cartilage has anatomic perforations and is easily penetrated below the hyoid bone, which allows direct extension of infrahyoid supraglottic cancer into this fascia-bound space [15]. In a histopathologic study of 80 resected larynges, Gregor [16] reported that PES invasion was present in 62.5% of cases. Pathologic evaluation of surgical specimens has shown a high incidence of PES invasion (T3) in patients with supraglottic carcinomas clinically staged as TI or T2 [6,17]. The PES invasion is more common with supraglottic carcinomas occurring below the level of the hyoid bone than for those suprahyoid in location (15% and 6%, respectively) [12,18]. Ljumanovic et al. [9] found, in a retrospective series of 84 patients with supraglottic tumors, that magnetic resonance imaging evidence of PES invasion was statistically associated with local recurrence in patients treated with definitive radiation therapy alone. Fletcher and Hamberger [19] suggested that local failure of radiation treatment of tumors involving the PES is due to the relatively avascular nature of this anatomical compartment. The supraglottic part of the larynx is characterized by a rich lymphatic network and carcinomas of this region have a strong predilection for cervical metastasis. Werner et al. [20] investigated the architecture and drainage patterns of the lymphatic system of the upper aerodigestive tract in 850 organ specimens using microscopic techniques combined with in vivo and in vitro lymphographic studies. They found that the lymph fluid of the supraglottic space drains through the lateral part of the thyrohyoid membrane (anterior boundary of the PES) in a mediolateral direction over three to six lymphatic channels.

In our study, the overall PES invasion rate was 23.8%. The patients with PES invasion had a significantly higher rate of cervical lymph node metastasis compared to patients without PES invasion. Patients with no evidence of PES invasion may have a survival benefit. The rate of 5-year disease-specific survival decreased dramatically in the presence of PES invasion and cervical lymph node metastasis using univariate analysis, but did not reach significance by multivariate analysis.

There were some limitations in this study. The main limitation was the retrospective aspect of the analysis. The second limitation was the small number of patients undergoing SCPL with CHP. Lastly, the median follow-up time of this study was rather short, which might lead to limitations of the disease-specific survival data. Further studies with a larger number of subjects should be our finding that PES invasion influences prognosis.

In conclusion, PES invasion was found to be significantly related to the presence of cervical lymph node metastasis and prognosis in patients undergoing SCPL with CHP. Therefore, PES invasion is a valuable marker that might be used to help guide the aggressiveness of therapy in future clinical trials and/or practice.