Thesis: Analysis of the efficacy of selective lateral neck dissection for laryngeal squamous carcinoma in the Department of Head and Neck Surgery, Cancer Hospital, Chinese Academy of Medical Sciences [Abstract] Objective To study the efficacy of lateral neck dissection (LND) in the selective treatment of patients with laryngeal squamous cell carcinoma (referred to as squamous carcinoma) without clinical lymph node metastasis (cN0). Methods Retrospective analysis of 110 patients with cN0 laryngeal squamous carcinoma who underwent LND at the Cancer Hospital of Chinese Academy of Medical Sciences from January 1997 to December 2002, including 72 cases of supraglottic type and 38 cases of glottic type. The pathological examination of 110 cN0 patients after selective laryngectomy revealed occult lymph node metastasis in 22 cases (20.0%), including 15 cases of supraglottic type (20.8%) and 7 cases of glottic type (18.4%). 37 positive lymph nodes were found in 145 lateral clearance specimens, and their distribution in the neck was as follows: 56.8% in zone II, 37.8% in zone III, and 5.4% in zone IV. . The 3-year neck recurrence rate was calculated as 3.7% (95% confidence interval 0.0%; 8.0%) according to the Kaplan-Meier method. Further stratified analysis revealed no significant differences in the 3-year neck recurrence rate between the following groups: patients with negative versus positive pathologic lymph nodes (4.2% versus 0.0%, P = 0.440); patients with supraglottic versus glottic type (4.2% versus 2.6%, P = 0.985); and patients with surgery alone versus combined treatment (4.5% versus 0.0%, P = 0.400) The Kaplan-Meier method in 110 cN0 patients estimated a 3-year survival rate of 90.8% (95% confidence interval: 84.5% to 97.1%). Conclusions The selective treatment of cN0 laryngeal squamous carcinoma patients with lateral neck debridement can achieve better results, both in terms of neck recurrence rate and long-term survival rate. The application of the concept of selective neck dissection for the treatment of squamous cell carcinoma of the head and neck (squamous carcinoma) has been reported since the mid-1980s [1,2], and has gradually replaced radical or modified radical neck dissection in Western countries because of good results, less surgical trauma, and better functional preservation [3]. Lateral neck dissection (LND), as an elective lymph node dissection, is used to selectively treat cN0 cases of laryngeal cancer by dissecting the lymph nodes in the jugular vein chain (zones II-IV), but it has been rarely reported in China and abroad [4, 5]. The results of our treatment of patients with laryngeal squamous carcinoma without clinical lymph node metastasis (cN0) are summarized and analyzed. 1 Data and methods 1.1 Study population inclusion criteria. A total of 135 patients with laryngeal cancer treated by lateral neck dissection from January 1997 to December 2002 in the medical record archive of the Cancer Hospital of the Chinese Academy of Medical Sciences were included in this study, and a total of 110 cases were included. The inclusion criteria were: ① surgery was the first treatment, and to avoid the effect of preoperative radiotherapy on lymph node morphology, patients with preoperative radiotherapy or chemotherapy were excluded, but patients with postoperative radiotherapy were included; ② primary squamous cell carcinoma of the larynx; ③ clinical examination of cervical lymph node grading (cN) was 0 according to the UICC/AJCC 2002 TNM staging criteria, and there was no distant metastasis. 1. 2 Clinical data. Of the 110 patients in this group, 90 were male and 20 were female; age ranged from 36 to 80 years, with a median age of 61 years. There were 72 cases of supraglottic type (cT1:12; cT2:29; cT3:25; cT4:6) and 38 cases of glottic type (including one case of transglottic type, cT1:0; cT2:12; cT3:15; cT4:11). Routine examination included palpation of the neck and B-mode ultrasound, and 94 patients (85%) were examined in combination with CT. cN0 was diagnosed by the absence of enlarged lymph nodes or enlarged lymph nodes ≤ 1 cm in diameter on clinical and imaging examination. 145 lateral neck dissection was performed in 110 patients. Bilateral neck clearance was mainly applied to patients with T3/T4 supraglottic laryngeal carcinoma, and was also related to the operator’s predisposition, without strict criteria. Subanatomic site, pathologic grading of the primary focus (pT) and the modality of the lateral neck clearing procedure (Table 1). pT grading was determined by the investigator based on a combination of gross pathology described intraoperatively and postoperative pathology department reports. All patients underwent partial or total laryngeal surgical resection at different sites and T classifications. 20 cases (18.2%) underwent postoperative radiation therapy (referred to as radiotherapy) at a dose of 50-64 Gy/5-7 weeks, with a mean of 58.3 Gy. The combined treatment was mainly applied to the primary site T4, postoperative pathology with poor prognostic indicators (e.g., multiple lymph node metastases, extraperitoneal invasion, unclear cut margins, etc.) and physician , the patient’s personal preference. The lateral neck clearance specimens were generally clipped according to the partition (II-IV) and sent for pathological examination, and the pathologists examined them according to the count of observable and palpable lymph nodes and routine sectioning. 1.3 Follow-up and statistical methods. The starting time of follow-up was the date of neck clearance surgery, and follow-up was performed until May 2005, or the date of death of the patient. The follow-up time range was 6 to 82 months, with a median time of 34 months. the Kaplan-Meier method was used to calculate the trend of neck recurrence or survival, using 95% confidence intervals. The terminal event for statistical analysis was neck recurrence or patient tumor death. Neck recurrence was defined as recurrence of neck lymph nodes on the side of neck clearance surgery, and contralateral neck recurrence was not counted. 2 Results 2.1 Lymph node pathology results. 145 lymph node counts of the side cleared specimens averaged 20. Occult lymph node metastases were found in 22 patients (20.0%) with a total of 24 sides (17%) in the neck (Tables 2-3). Of these, pN1=15 sides and pN2=9 sides. Extraperitoneal invasion was found on 4 sides (16.7%) of the metastatic lymph nodes. A total of 37 positive lymph nodes were found, and the distribution of the number of positive lymph nodes in the II-IV regions of the neck was as follows: 21 in region II (56.8%), 14 in region III (37.8%), and 2 in region IV (5.4%). 2.2 Recurrence in the neck. In this group, 14 cases (12.7%) of laryngeal cancer recurrence or metastasis were found in the follow-up. The time of neck recurrence in 3 cases was the 5th, 7th and 35th months after lateral cervical clearance, respectively. In two of these cases, the site of recurrence occurred within the scope of lateral neck clearance (zone II and zone III, respectively); in one case, bilateral neck recurrence occurred after unilateral clearance, and the site of recurrence on the ipsilateral side of clearance was outside the scope of lateral neck clearance (zone VI). All three patients with neck recurrence died, although one of them underwent salvage surgery. The 3-year neck recurrence rate was 3.7% according to the Kaplan-Meier method, with a 95% confidence interval of 0.0% to 8.0%. Further stratified analysis was performed according to lymph node pathology (pN) findings, laryngeal subanatomical site, and whether postoperative adjuvant radiotherapy was available (Table 3). pN0 and pN+, supraglottic versus glottic type, and no statistically significant differences in 3-year neck recurrence rates between patients with surgery alone and postoperative radiotherapy (Table 4). 2.3 Survival rate. By the follow-up cut-off date, there were 13 deaths, including 8 from primary laryngeal cancer, 2 from second primary cancer, and 3 from intercurrent disease. 2 cases were lost to follow-up. The 3-year survival rate was estimated at 90.8% (95% confidence interval: 84.5%-97.1%) according to the Kaplan-Meier method. The 3-year survival rates were 90.8% and 90.6% (P = 0.820) for supraglottic (n = 72) and glottic patients (n = 38), respectively; 92.6% and 90.1% (P = 0.432) for stage I and II (n = 53) and stage III and IV (n = 57) patients, respectively; pN0 (n = 88) and pN+ (n = 22) patients, respectively. survival rates were 93.1% and 79.6%, respectively (P = 0.072). 3.Discussion Lateral neck dissection is one of the selective (zoned) neck dissection procedures, which is a limited neck dissection based on the pattern of cervical lymph node metastasis in patients with laryngeal squamous carcinoma, and only the internal jugular vein lymphatic chain, i.e., lymph nodes in zones II-IV, is dissected [6]. Characteristically, the sternocleidomastoid muscle, paramedian nerve, internal jugular vein and cervical plexus nerve and zone I and V lymph nodes to be removed by conventional neck clearance surgery are preserved, and the neck clearance is reduced. The tumor is not affected by the reduced surgical extent, but the patient’s function is significantly improved [7].Davidson [8] analyzed a sample of 1123 head and neck cancers including laryngeal cancer, of which 282 N0 patients had a metastasis rate of only 1% in region V. In 1999, the Brazilian Head and Neck Oncology Scientific Research Group published the results of a modified neck clearance versus lateral neck The results of a randomized study of 132 patients with supraglottic laryngeal cancer with cN0 [4] showed a recurrence rate of 4.8% and 2.5% in the neck lymph nodes in the two groups of patients before and after the results. The 3-year neck recurrence rate in our data was 3.7%, which is consistent with the results reported abroad. The literature reports that the occult metastasis rate of patients with supraglottic laryngeal cancer ranges from 25% to 39%, and the occult metastasis rate of T3/T4 glottic laryngeal cancer ranges from 18% to 30% [9-11]. The chance of occult metastasis in our cN0 patients was 20%, including 20.8% in supraglottic type and 18.4% in vocal type, and the latter had a chance of occult metastasis of 24% in T3/T4 patients (6/25). There have been many debates in the past on the management of patients with cN0 laryngeal cancer, which were broadly divided into three categories: advocating total neck clearance, advocating supraglottic clearance, and observation. The advent of lateral neck clearance has basically solved this dilemma. In comparison between patients with radical neck clearance and modified neck clearance, the rate of periapical dysfunction p neck skin sensory loss and damage to neck appearance were significantly lower in patients after elective neck clearance [7]. Unilateral or bilateral cervical elective dissection does not cause significant functional and cosmetic impairment in patients, and may be the best surgical approach for the management of cN0 at this time for diseases and cases with a high rate of potential lymph node metastasis. Although sentinel lymph node detection has also been applied to head and neck squamous carcinoma in recent years on a trial basis, there are some technical difficulties and limitations. For example, deep in the larynx and laryngopharynx, preoperative injection of tracer is inconvenient as well as inaccurate; the primary foci are close to the location of the first station lymph nodes, which are not easily distinguished by isotope detectors, etc. Therefore, it has been argued that the promotion of this technique in head and neck surgery seems to be less necessary [12]. The recurrence rate in our group was 4.5% for surgical neck alone and 0.0% for postoperative radiotherapy, which did not reach a statistically significant difference (p = 0.400), probably related to the small sample size. For the same reason, the difference in neck recurrence rate between pN0 and pN+ patients was also not significant (4.2% versus 0.0%, p = 0.440), but the 3-year survival rates were 93.1% and 79.6%, respectively, with a difference approaching significance (p = 0.072). Lymph node metastasis may be a prognostic factor compared to laryngeal cancer subanatomy and tumor stage. It is generally believed that adjuvant radiation therapy is not necessary for patients with pN0 and pN1, and only adjuvant radiation therapy for patients with pN2 or envelope invasion can reduce the recurrence rate in the neck [13]. There were few cases of N2 or lymph node envelope invasion in our data, so it was not possible to re-stratify the analysis of pN+ patients. The means of selective treatment for cN0 in the neck of head and neck tumors is generally consistent with the means chosen for the treatment of the primary site [3, 4, 12, 13], i.e., if the primary site is treated with radiation therapy, then the neck can also be treated with selective radiation therapy at the same time. Radiation therapy has equivalent efficacy for potential metastases. If the primary site is treated by surgery, the neck is also treated by selective neck clearance surgery at the same time. When laryngeal cancer is treated by surgery in Cancer Hospital of Chinese Academy of Medical Sciences, the conventional method of neck surgery is selective lateral neck clearance. The indications are patients with supraglottic T1 to T4N0 and vocal T3 to T4N0 of laryngeal cancer. Bilateral selective cervical clearance is mainly applied to patients with midline lesions or advanced lesions, such as metachronous cancer p supraglottic T3/T4 and vocal T4. In conclusion, for patients with cN0 laryngeal squamous carcinoma, proper application of cervical lateral clearance surgery can achieve better treatment results, whether judged by neck recurrence rate or long-term survival rate index. Radical neck debulking surgery, which is more invasive, should no longer be used.