Oral cavity cancers encompass a diverse group of malignancies affecting different subsites such as lips, tongue, gingiva, palate, buccal mucosa and floor of mouth. Globally, these cancers constitute a significant health burden, with substantial variability in the incidence rates and demographic distribution. Oral cancer is the sixth most common cancer worldwide. India leads in oral cancer cases, making up one-third of the global burden, where the incidence and mortality rates are also on the rise.[1] Etiologically, tobacco use, alcohol consumption, betel nut chewing and infection with high-risk strains of human papillomavirus (HPV) are considered to be primary contributors for the development of oral cavity cancers. These factors induce genetic mutations in oral mucosal cells, initiating the malignant transformation. [2] Despite advances in early detection and treatment modalities, the prognosis for oral cavity cancer patients remains guarded, particularly in advanced stage tumours. In oral cavity cancers, metastasis to cervical lymph nodes is common due to the direct lymphatic drainage pathways from the primary tumour site. [3][4][5] The likelihood and pattern of lymph node involvement depend on factors such as tumour size, location, histological grade and depth of invasion. Accurate preoperative staging using imaging modalities like ultrasound, CT scan and MRI helps identify suspicious lymph nodes and determine the appropriate extent of neck dissection [6][7] Oral cavity cancers, often metastasize to cervical lymph nodes causing drastic change in prognosis. Studies have suggested that effective surgical management requires thorough removal of these nodes along with resection of some non-lymphatic structures to reduce the risk of recurrence and improves survival rate. The dissection of parotid tail is thus, a critical component of neck dissection in these patients.[8] Parotid tail, is also pivotal in the management of oral cavity cancers due to its proximity to the oral cavity and its susceptibility to involvement in oral cancers. Although the frequency is extremely low, several studies with small case series have reported the potential of OSCC to metastasize into the parotid region. The necessity of resecting the parotid nodes in neck dissections for oral cancer is not clear from the literature. In this study we aim to evaluate the incidence of involvement of parotid tail in oral cavity cancers. AIMS & OBJECTIVES AIMS The aim was to evaluate the incidence of involvement of parotid tail in oral cavity cancers. OBJECTIVES: 1. To correlate the size and site of primary lesion with the involvement of parotid tail. 2. To correlate the grade of primary lesion with the parotid tail involvement. 3. To correlate the demographic profile of patients with the involvement of parotid tail.

Study Setting: Departments of Otorhinolaryngology and Pathology, in a tertiary care oncology centre New Delhi. Study Design: Prospective observational single centre cross sectional study. Sample Technique: Convenience sampling Duration of Study: 1.5 years Sample Size: All the patients of oral carcinoma who underwent primary surgery with comprehensive and selective neck dissection in our department within a period of 18 months from November 2022 to May 2024. Study Population: All patients of oral cavity carcinoma, who underwent primary surgery with comprehensive and selective neck dissection in the Department of ENT –HNS, in a tertiary care oncology centre. Inclusion criteria 1. All patients of oral carcinoma who underwent primary surgery with comprehensive and selective neck dissection as part of treatment modality. Exclusion criteria 1. Prior head & neck radiation or prior parotid surgery on the same side. 2. Distant metastasis (M1) at presentation precluding curative surgery. 3. Non-squamous primary histology (unless you choose to include). 4. Patient refusal/unfit for surgery. 1. Preoperative Evaluation: • Comprehensive clinical assessment, including physical examination and imaging studies (e.g., contrast CT/MRI contrast) was done, to determine the extent and location of lymph node involvement. • Discussion in multidisciplinary tumour boards were done to finalize treatment plans, including the type of neck dissection and the appropriate surgical approach and reconstruction (e.g., selective, modified radical, or radical neck dissection). 2. Surgical Technique: • Standard surgical protocol was followed: Neck dissection followed by adequate excision of the primary tumor was done. This was followed by reconstruction. • Identification of Landmark Structures was done such as the greater auricular nerve, the retro-mandibular vein, and the posterior belly of the digastric muscle is crucial. Careful dissection avoids injury to the facial nerve, which can be identified using nerve monitoring techniques. 3. Dissection of the Parotid Tail was done: Marginal mandibular nerve identified and preserved after careful elevation of upper skin flap in sub-platysmal plane. During resection of level 1b region, retro-mandibular vein was identified, ligated and transected just below the marginal mandibular nerve. The part of the parotid gland below the marginal mandibular nerve (parotid tail) was resected out and sent separately for HPE. 4. Dissection of Lymph Node: Meticulous dissection of lymph node levels based on the planned neck dissection type (e.g., selective, modified, radical) was done. Preservation of critical structures, such as major blood vessels (internal jugular vein), nerves (e.g., spinal accessory nerve) depending upon the type of neck dissection was done. 5. Haemostasis and Closure was done: Control of bleeding, closure of incisions using sutures or staples, and placement of drains as necessary to prevent haemorrhage and postoperative fluid accumulation. 6. Postoperative Care: • Monitoring for immediate postoperative complications, such as bleeding, infection, and nerve injury. • Pain management, wound care, and initiation of rehabilitation protocols, including physical therapy for optimizing shoulder function and speech therapy for managing swallowing and speech difficulties. Histopathological Examination (HPE) Sampling 1. Specimen Handling: • Immediate transfer of excised lymph nodes and separate specimen of parotid tail to the pathology laboratory in a formalin-filled container to prevent tissue degradation. • Labelling of specimens with patient identifiers and surgical details to ensure accurate documentation. 2. Processing and Gross Examination: • Inspection of lymph node specimens by a pathologist to assess size, colour, consistency, and presence of metastatic nodules. • Sectioning of lymph nodes and parotid tail into slices followed by embedding in paraffin blocks for microscopic examination. 3. Microscopic Examination: • Preparation of thin tissue sections (4-5 micrometers thick) using a microtome and staining with hematoxylin and eosin (H&E) for visualization under a light microscope. • Evaluation of tissue sections for the presence of metastatic deposits, including assessment of tumour size, histological subtype, margins, and lymphovascular invasion. • Reporting findings according to standardized pathological staging systems (e.g., TNM classification) to guide clinical management and prognostication.

This study was conducted at the Department of ENT - Head and Neck Surgery (HNS) and Department of Pathology, at a tertiary care oncological Center in New Delhi. Utilizing an observational cross-sectional design, we examined the incidence of parotid tail involvement in oral cavity carcinoma. A convenient sampling technique was employed over a duration of 1.5 years, resulting in a sample size of 40 patients. The study population comprised all patients diagnosed with oral carcinoma who underwent comprehensive and selective neck dissection in the Department of ENT-HNS at HIMSR and HAHC Hospital. Table 1: Describing the study groups as per Age Age Group Frequency Percentage 20 to 30 years 4 10.00% 31 to 40 years 10 25.00% 41 to 50 years 16 40.00% 51 to 60 years 5 12.50% >60 years 5 12.50% Total 40 100.00% The study's age distribution revealed that the majority of patients with oral cavity cancers were in the 41 to 50 years age group, accounting for 40% of the sample. Patients aged 31 to 40 years comprised 25% of the study population, while those aged 51 to 60 years and over 60 years each represented 12.5%. The youngest age group, 20 to 30 years, had the lowest incidence, making up only 10% of the cases. This distribution indicates a higher prevalence of oral cavity cancers in middle-aged individuals, with a noticeable decline in both younger and older age groups. Table- 2: Describing the study groups as per ULCERATION Ulceration Frequency Percentage Present 39 97.50% Absent 1 2.50% Total 40 100.00% The occurrence of ulceration among the study participants was notably high, with 97.5% of the patients exhibiting ulceration associated with their oral cavity cancers. Only one patient (2.5%) did not have ulceration. This overwhelming prevalence of ulceration highlights its common presence in patients with oral cavity cancers in the studied group, suggesting that ulceration may be a significant clinical feature of the disease. Table - 3: Describing the study groups as per SITE OF LESION Site Frequency Percentage Lip 1 2.50% Alveolus 5 12.50% Buccal 15 37.50% Sulcus 5 12.50% Tongue 14 35.00% Total 40 100.00% The distribution of lesion sites among the study participants showed that the buccal mucosa was the most common site, accounting for 37.5% of the cases, followed closely by the tongue at 35%. Lesions located on the alveolus and in the sulcus were each observed in 12.5% of the patients. The least common site was the lip, with only 2.5% of the cases. These findings highlight that the buccal mucosa and tongue are the predominant sites for oral cavity cancers in the studied population, suggesting these areas as critical focal points for screening. Table 4: Describing the study groups as per HISTOLOGICAL GRADE Histological Grade Frequency Percentage Moderately differentiated 19 47.50% Poorly differentiated 1 2.50% Well differentiated 20 50.00% Total 40 100.00% The histological grading of tumours in the study population revealed that 50% of the cases were well differentiated, while 47.5% were moderately differentiated. Only 2.5% of the tumours were poorly differentiated. These findings suggest that a majority of the tumours in the studied group exhibited either well or moderate differentiation, with poorly differentiated tumours being relatively rare. The predominance of well-differentiated and moderately differentiated tumours has significant implications for prognosis and treatment planning in patients with oral cavity cancers. Table 5: Describing the study groups as per T STAGE T Stage Frequency Percentage T1 5 12.50% T2 9 22.50% T3 15 37.50% T4 1 2.50% T4a 10 25.00% Total 40 100.00% The distribution of T stages among the study participants showed that the most common stage was T3, representing 37.5% of the cases. This was followed by T4a at 25% and T2 at 22.5%. T1 stage lesions accounted for 12.5% of the patients, while T4 was the least common, seen in only 2.5% of the cases. This staging distribution indicates that a significant proportion of the patients were diagnosed at more advanced stages (T3 and T4a), underscoring the importance of early detection and timely intervention in the management of oral cavity cancers. Table 6: Describing the study groups as per N STAGE N Stage Frequency Percentage No 24 60.00% N1 1 2.50% N2 3 7.50% N2a 1 2.50% N2b 10 25.00% N3b 1 2.50% Total 40 100.00% The analysis of N stages among the study participants revealed that 60% of the patients had no regional lymph node involvement (N0). Among those with lymph node involvement, N2b was the most common, occurring in 25% of the patients. N1, N2, N2a, and N3b stages were less frequent, each representing 2.5% to 7.5% of the cases. This distribution suggests that the majority of patients were diagnosed without lymph node metastasis, while a notable portion had more advanced nodal involvement, particularly at the N2b stage. Table 7: Describing the study groups as per TAIL OF PAROTID Tail of Parotid Frequency Percentage Negative 40 100 % Positive 0 0% Total 40 100.00%

Our study was conducted to analyse the incidence of parotid tail involvement in oral cavity cancers also focusing on any correlation of various demographic, clinical and histopathological factors with it. This study was conducted in the Departments of Otorhinolaryngology and Pathology at a tertiary care Oncology Centre. It included 40 patients with oral cavity carcinoma undergoing neck dissection from November 2022 to May 2024. The age distribution revealed that the majority of patients (40%) were in 41 to 50 years age group. The 31 to 40 years age group constituted 25% of the sample, while those aged 51 to 60 years and over 60 years each represented 12.5%. The youngest group (20 to 30 years) comprised only 10% of the cases, indicating a higher prevalence of oral cavity cancers in middle-aged individuals. Similarly, Harada et al conducted study in patients with oral carcinomas who underwent neck dissection, their ages ranged from 23-85 years with mean of 60.5years. A different research done by Xiao et al in 47 patients of oral squamous cell carcinoma,20 patients were below the age of 60 years and 27 were above 60 years of age.[9][10] In our study Ulceration was highly prevalent along with the lesion, as observed in 97.5% of the patients. The buccal mucosa, 15 cases (37.5%) and tongue 14 cases (35%) were the most common sites for lesion and ulceration, followed by alveolus (12.5%), gingivobuccal sulcus (12.5%) and lip (2.50%). Where as in the study done by Harada et al on 253 patients of oral cancer the most common primary tumour site was tongue 122(48%) followed by lower gum 78(30%), buccal mucosa 23 (9%), floor of mouth 18 (7.11%) and upper gum 12 (4.7%) [9] In line with a study done by P.K. Sahu et al the commonest site was buccal mucosa (25.78%) followed by tongue(21.09%),lower alveolus(21.09%), retromolar trigone (11.72%), floor of mouth (10.16%),mandible (05.47%) and upper alveolus (04.69%). [11] In our study most tumours were well-differentiated (50%) or moderately differentiated (47.5%), with poorly differentiated tumours being rare (2.5%). Whereas in a study done by Xiao et al well differentiated and more moderate differentiated tumour were( 74.5%) and poor differentiated was (25.5%).[10] Advanced stages (T3 and T4a) were common in our study, representing 37.5% and 25% of the cases, respectively. Regional lymph node involvement was absent in 60% of patients, but N2b was the most common stage among those with involvement (25%). Whereas in a study done by P.K. Sahu et at out of 128 patients T3 was most common (32.81%) followed by T2(31.25%).[11] In a study conducted by P.K. Sahu et al out of 128 patients 85 patients showed nodal metastasis whereas, our study, the mean number of lymph nodes involved was 1.28, with most patients having tumour-free surgical margins (97.5%).This high percentage of tumour-free margins indicates effective surgical intervention.[11] Parotid tail is the inferior most part of parotid gland. One of the branch of facial nerve is marginal mandibular nerve which runs through this part of parotid gland and damage to this nerve leads to weakness of the angle of mouth. Resection of tail of parotid is presently an integral part of various type of neck dissections (Radical, Modified radical and Selective neck). However, incidence of involvement of parotid lymph nodes and more specifically in tail in oral carcinoma is very low even in the available literature. In our study out of 40 resected parotid tails, none demonstrated metastasis histopathologically. This incidence suggests that while parotid tail involvement is a concern, it is relatively uncommon in the studied population. As there is no occult or pathological appreciable metastasis in parotid tail specimen in our study so correlation with histopathological parameters like tumour size, grade, metastasis and lympho-vascular invasion could not be established. According to the study done by Zhang et al 1358 cases of confirmed oral squamous cell carcinoma recurrent metastasis in parotid was reported in 10 patients, 8 being in the inferior lymph node in the parotid tail.[12] There is no standardization in the level of resection of parotid tail in the literature. Harada et al practised it as parotid tissue below the level of marginal mandibular nerve while other authors as inferior 2cm of parotid gland.[9] In our study we followed resection of parotid tissue below the level of marginal mandibular nerve. Recurrence in intra-parotid nodes above marginal mandibular nerve has been seen in spite of resection of parotid tail in Harada’s study which blurs the importance of tail resection.[9] Moreover according to study by Wijin et al, parotid lymph node are not the first echelon nodes for SCC of Oral Cavity.[13] Metastasis in parotid nodes are generally found with recurrent carcinoma instead of primary carcinoma as indicated by Olsen.[14] In current literature there is no study comparing the recurrence rate after parotid tail sparing neck dissections. Study conducted by Conley and Arena indicated the possibility of parotid node metastasis in oral carcinoma but had raised the query regarding routine resection of parotid tail during neck dissection [15] Our study supports a debatable question of feasibility of parotid tail preservation during neck dissection to prevent morbidity due to marginal mandibular nerve. However studies with long term follow-up of patients having oral cavity carcinoma who have undergone parotid tail sparing neck dissections are needed for oncological safety of this approach.

Incidence of involvement of parotid tail in oral squamous cell carcinoma patients is very low and its preservation to limit the morbidity of marginal mandibular nerve should be considered. However, study involving large study population for comparison of prognostic values of tail preserving and sparing neck dissection are needed to solve this issue.

1. Borse V, Konwar AN, Buragohain P. Oral cancer diagnosis and perspectives in India. Sens Int. 2020;1:100046. doi:10.1016/j.sintl.2020.100046. Epub 2020 Sep 24. PMID: 34766046; PMCID: PMC7515567. 2. American Cancer Society. (2023). Causes, Risk Factors, and Prevention of Oral Cavity and Oropharyngeal Cancer. Retrieved from https://www.cancer.org/cancer/oral-cavity-and-oropharyngeal-cancer/causes-risks-prevention.html 3. National Cancer Institute. (2022). Oral Cancer Treatment (Adult) (PDQ®)–Health Professional Version. Retrieved from https://www.cancer.gov/types/head-and-neck/hp/oral-treatment-pdq 4. El-Naggar, A. K., Chan, J. K. C., Grandis, J. R., Takata, T., & Slootweg, P. J. (Eds.). (2017). WHO Classification of Head and Neck Tumours (4th ed., pp. 11-24). IARC Press, Lyon 5. Carpenter, G. H. (2019). Anatomy and Physiology of the Salivary Glands. In Handbook of Oral Biology (1st ed., pp. 157-172). Wiley-Blackwell. 6. Ferlito, A., Shaha, A. R., Silver, C. E., Rinaldo, A., Mondin, V., & Gailus-Durner, V. (2011). Incidence and sites of lymph node metastases from head and neck cancers: A review. Acta Oto-Laryngologica, 121(1), 20-24. DOI:10.1080/000164801750058498 7. Liao, L. J., Hsu, W. L., Wang, C. T., Lo, W. C., Cheng, P. W., & Shueng, P. W. (2012). Prognostic value of pretreatment imaging in patients with oral cavity squamous cell carcinoma. Head & Neck, 34(1), 53-58. DOI:10.1002/hed.21705 8. Wax, M.Wax, M. K., & Goldenberg, D. (2017). Neck Dissection in Oral Cavity Cancer. Oral Oncology, 53(3),177-185. doi:10.1016/j.oraloncology.2016.11.003 9. Harada H, Omura K. Metastasis of oral cancer to the parotid node. Eur J Surg Oncol. 2009 Aug;35(8):890-4. 10. Xiao M, Song H, You Y, Liu M, Yang X, Wang Y. Metastasis of oral squamous cell carcinoma to the parotid lymph nodes. Int J Oral Maxillofac Surg. 2021 Apr;50(4):437-443. 11. Sahu, P.K., Kumar, S. Epidemiological Aspects of Oral Cancer in North Indian Population. Indian J Otolaryngol Head Neck Surg 71 (Suppl 1), 944–948 (2019). https://doi.org/10.1007/s12070-019-01629-7. 12. Zhang WB, Wang Y, Mao C, Guo CB, Yu GY, Peng X. Oral Squamous Cell Carcinoma with Metastasis to the Parotid Lymph Node. Chin J Dent Res. 2019;22(3):175-179 13. Tan, Y., Wang, Z., Xu, M. et al. Oral squamous cell carcinomas: state of the field and emerging directions. Int J Oral Sci 15, 44 (2023). https://doi.org/10.1038/s41368-023-00249-w 14. Olsen SM, Moore EJ, Koch CA, Kasperbauer JL, Olsen KD. Oral cavity and oropharynx squamous cell carcinoma with metastasis to the parotid lymph nodes. Oral Oncol. 2011 Feb;47(2):142-4. 15. CONLEY J, ARENA S. PAROTID GLAND AS A FOCUS OF METASTASIS. Arch Surg. 1963 Nov;87:757-64. doi: 10.1001/archsurg.1963.01310170043009. PMID: 14058839.