Submandibular gland transfer into the temporal fossa in patients with oral squamous cell carcinoma: A viable option to prevent radiation-induced xerostomia

Highlights

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Preservation of submandibular gland during lymph node dissection is oncologically safe in selected patients with OSCC.
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Temporal fossa is an anatomical site receiving very low dose of radiation in patients with OSCC treated by radiotherapy.
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SMG transfer into the temporal fossa could help for reducing radiation-induced xerostomia in patients with OSCC.

Abstract

Oral squamous cell carcinoma (OSCC) is associated with an important mortality and morbidity related to surgery and radiotherapy. In particular, radiation-induced xerostomia has a major impact on patient’s quality of life. Although intensity-modulated radiation therapy allowed mean dose reduction to the spared submandibular gland (SMG) in patients with head and neck squamous cell carcinoma, xerostomia is still an important sequela for patients treated for an OSCC. SMG surgical transfer into anatomical subsite receiving very low radiation doses is a promising approach to prevent xerostomia. Based on a literature review and data from our institutional cohort, we analyzed the oncological safety of SMG preservation. Then, we discussed the feasibility and relevance of SMG transfer into the temporal fossa, in order to prevent radiation-induced xerostomia in patients with OSCC.

Introduction

Oral squamous cell carcinoma is associated with a substantial morbidity and mortality, which is mainly due to a high risk of loco-regional recurrence. Because of the incidence of lymph node metastasis, a rigorous neck node management is crucial for patients suffering from OSCC. However, de-escalation strategies have been recently proposed for neck management of those patients. In particular, in patients with early OSCC (cT1-T2N0), recent randomized clinical trials demonstrated the oncologic equivalence of the sentinel node biopsy (SN) and neck lymph node dissection (ND) with lower morbidity in the SN arm. Moreover, preservation of submandibular gland during ND could also be considered regarding the low incidence of invasion of the SMG in patients with OSCC . In patients with advanced OSCC requiring adjuvant radiation therapy, the SMG preservation could allow its transposition into a poorly irradiated area in order to prevent radiation-induced xerostomia . Although SMG transfer into the temporal fossa has not been yet performed in patients with OSCC, the purpose is to review the literature and our institutional cohort data in order to discuss its safety and feasibility to prevent radiation-induced xerostomia in this clinical setting.

Oncological safety of submandibular gland preservation

Literature review

A previous systematic review and meta -analysis, based on a total of 4458 patients and 5037 glands analyzed, showed a SMG involvement rate of 1.8 % when considered per patient, and 1.6 % when considered per gland . We updated the literature review using Pubmed database on June 12th, 2024 to retrieve studies for submandibular gland involvement in patients with oral squamous cell carcinoma. We excluded case reports and studies including less than 10 patients. A total of 31 studies were identified ( Table 1 ), with six studies including more than 300 patients . In total 5665 patients and 6309 submandibular glands were analyzed. The incidence of SMG invasion is low according to previous retrospective (27/31) and prospective (4/31) studies reporting a rate between 0 to 9.5 % per gland and 10 % per patients. The rate of involvement of the submandibular gland was 2.2 % per gland (138/6309) and 2.4 % (138/5665) per patient. Even if most of the articles were retrospective studies, this review suggests the feasibility of the SMG preservation in patients with oral squamous cell carcinoma. Notably, a non-randomized prospective cohort study showed that the 5-year locoregional control as well as the disease-specific survival rates were not different between the SMG-sparing and SMG-excision groups .

Table 1

Literature review of submandibular gland (SMG) invasion.

Pubmed ID	Year	Data collection	Total patients	Total SMG	Nb of involved SMG	% invasion per gland	% invasion per patient
15,459,920	2004	retrospective	169	196	9	4,6	5,3
19,360,744	2009	retrospective	342	383	7	1,8	2,0
18,607,927	2009	retrospective	201	316	2	0,6	0.9
19,881,371	2009	retrospective	130	171	6	3,5	4,6
19,475,546	2009	retrospective	132	253	1	0,4	0,7
20,737,484	2011	prospective	20	33	0	0	0
21,729,447	2011	retrospective	52	52	1	1,9	1,9
22,017,858	2012	retrospective	69	69	2	2,9	2,9
22,944,141	2012	retrospective	194	229	3	1,3	1,5
23,853,397	2013	retrospective	236	294	13	4,4	5,5
25,149,835	2014	retrospective	110	110	2	1,8	1,8
25,621,270	2015	retrospective	94	98	3	3,1	3,2
25,724,734	2015	retrospective	175	163	6	3,7	3,4
27,508,132	2016	retrospective	112	112	0	0	0
27,232,643	2016	prospective	137	152	0	0	0
27,450,469	2017	retrospective	176	NA	2	NA	1,1
29,720,283	2018	retrospective	155	183	2	1,1	1,3
30,401,471	2018	retrospective	586	622	26	4,2	4,4
31,864,860	2019	retrospective	95	116	4	3,4	4,4
31,876,743	2019	prospective	330	363	7	1,9	2,1
31,866,411	2020	retrospective	302	355	1	0,3	0,3
33,968,233	2020	retrospective	149	157	7	4,5	4,7
33,940,532	2020	retrospective	303	366	4	1,1	1,3
33,109,130	2021	prospective	106	106	0	0	0
34,900,678	2021	retrospective	145	173	1	0,6	0,7
33,654,687	2021	retrospective	131	NA	1	NA	0,7
34,972,007	2021	retrospective	60	60	0	0	0
35,110,897	2021	prospective	60	63	6	9,5	10
36,742,853	2022	retrospective	83	83	6	7,2	7,2
37,280,380	2023	retrospective	642	852	12	1,4	1,8
37,871,650	2024	retrospective	173	179	4	2,2	2,3
Total			5665	6309	138	2,2	2,4