Long-term outcomes in advanced anterior skull base malignancy: a single quaternary institution experience.

BACKGROUND: Advanced skull base malignancies are a heterogenous subset of head and neck cancers, and management is often complex. In recent times, there has been a paradigm shift in surgical technique and the advent of novel systemic options. Our goal was to analyse the long-term outcomes of a single quaternary head and neck and skull base service. METHODS: A retrospective review of 127 patients with advanced anterior skull base malignancies that were treated at our institution between 1999 and 2015 was performed. Multiple variables were investigated to assess their significance on 5 and 10-year outcomes. RESULTS: The mean age was 60.9 (± 12.6 SD). Sixty-four percent were males and 36% were females. Ninety percent of patients had T4 disease. Median survival time was 133 months. The 5-year overall survival (OS) was 66.2%, disease-specific survival (DSS) was 74.7%, and recurrence-free survival (RFS) was 65.0%. The 10-year OS was 55.1%, DSS was 72.1%, and RFS was 53.4%. Histological type and margin status significantly affected OS & DSS. CONCLUSION: Surgical management of advanced skull base tumours has evolved over the last few decades at our institution with acceptable survival outcomes and complication rates. Histological diagnosis and margin status are the main predictors of survival. The addition of neoadjuvant systemic agents in current trials may improve outcomes.

Clinical outcomes in perineural spread of cutaneous squamous cell carcinoma via the ophthalmic nerve.

BACKGROUND: There are no large studies reporting oncological or survival outcomes for patients diagnosed with perineural spread (PNS) of cutaneous squamous cell carcinoma (cSCC) via the ophthalmic nerve (V1). Where orbital exenteration may be necessary for curative treatment, it is critical to have survival data with which the morbidity associated with surgical treatment can be justified. Furthermore, with the emerging treatment option of immunotherapy, current standard of care outcomes are needed to help guide future trial design and eventually changed management guidelines. OBJECTIVE: To determine the oncological and survival outcomes observed in patients with PNS of cSCC via V1. MATERIALS AND METHODS: Retrospective analysis of prospectively maintained cohort of patients with PNS of cSCC via V1 treated in a tertiary Australian head and neck oncology/skull base referral center. Consecutive sample of 53 patients managed between March 1, 1999 and April 30, 2020. Follow-up closure date was September 1, 2021. Curative-intent surgery, curative-intent radiotherapy, or palliative care was undertaken. Endpoints included five-year overall, disease-specific, and disease-free survival from the date of treatment. RESULTS: Five-year Kaplan-Meier overall survival was 61.9% (95% CI 46.2%-74.3%), with disease-specific survival of 74.6% (95% CI 58.8%-85.3%), and disease-free survival 62.1% (95% CI 46.5%-74.3%). Survival was superior in patients treated via surgery and adjuvant radiotherapy than in those receiving surgery alone or definitive radiotherapy. Survival was superior among patients with less advanced disease as assessed by the Williams zonal staging system; patients with Zone 1 disease had disease-specific survival of 94.1% at 5 years with 82.5% disease-free survival. DISCUSSION: Five-year oncological and survival outcomes in this cohort were favorable. Superior survival was observed in patients treated with curative-intent surgery and adjuvant radiotherapy. Less extensive disease as delineated by the Williams zonal staging system was associated with improved survival. CONCLUSION: Surgical resection with adjuvant radiotherapy confers favourable oncological and survival outcome in patients with V1 PNS, particularly with early disease limited to Zone 1.

A phase Ib study to assess the safety of the human papillomavirus DNA vaccine (AMV002) in combination with durvalumab for HPV-associated oropharyngeal squamous cell carcinoma.

Background: Programmed cell death ligand 1 (PD-L1) inhibitors have limited efficacy as monotherapy in patients with recurrent/metastatic (R/M) Human Papilloma Virus (HPV) oropharyngeal squamous cell carcinoma (OPSCC). A phase I study of the therapeutic HPV-16 DNA vaccine AMV002 in curatively treated patients with OPSCC demonstrated a measurable immune response against HPV while being associated with high safety and tolerability. This prospective phase Ib single centre pilot study aims to test the safety and tolerability of combined PD-L1 inhibitor, Durvalumab, with AMV002 in 12 patients with recurrent OPSCC. Methods: Participants had evidence of R/M HPV-associated OPSCC. They received three intradermal administrations of AMV002 with Durvalumab followed by Durvalumab maintenance. Safety and tolerability data was the primary endpoint. The study was conducted with ethical approval (HREC/2018/QMS/47293) in Brisbane, Australia. Findings: The most common adverse event (AE) related to vaccine administration was erythema at the injection site. There were no grade 3 or 4 vaccine related AEs. There was one presumed immune-related grade 3 elevation in lipase secondary to Durvalumab with no intervention required. No patient ceased study due to treatment-related AEs. At week 16, objective response rate was 8% (N=1) and disease control rate was 17% (N=2). At a median follow up of 25.6 (20.0-26.6) months there was one long term complete response while all other participants developed progressive disease. Of the 11 evaluated patients, 9, (82%) had E6 and/or E7-specific T cell responses to the vaccine. Conclusion: The combination of AMV002 therapeutic HPV-16 vaccine and Durvalumab was found to be safe and well tolerated with no increased safety signals generated. T cell responses to vaccine were observed but further work will be required to improve efficacy.

Evaluation of facial nerve perineural spread from cutaneous squamous cell carcinoma using 3T MR neurography.

INTRODUCTION: Perineural spread (PNS) is a rare but potentially fatal consequence of cutaneous squamous cell carcinoma (cSCC) of the head and neck. We aimed to evaluate the accuracy of 3T MR neurography in detecting and defining the extent of facial nerve (VII) PNS from cSCC, and highlight characteristic radiological features in peripheral branches to improve early diagnosis. METHODS: Single-institution retrospective review of 38 patients with clinical, radiological, and/or histopathological findings consistent with VII PNS from cSCC who underwent pre-operative 3T MR neurography. RESULTS: Compared to histopathology (gold standard), 3T MR neurography had a sensitivity of 89% and positive predictive value of 97%. In true-positive cases (n = 33), zonal extent was correctly identified in 100%. Seventy-nine% had simultaneous trigeminal nerve (V) PNS, mostly involving the auriculotemporal branch of the mandibular nerve (64%). When the causative lesion was absent (n = 23), the extra-temporal VII demonstrated asymmetrical enhancement alone (n = 6), bulky expansion (n = 8), or extra-neural spread (n = 9). Peripheral VII branch involvement, particularly the buccal and zygomatic, was readily identified using known anatomical landmarks. CONCLUSION: 3T MR neurography is highly accurate in evaluating VII PNS from cSCC, and thus should be specifically requested by physicians if suspicious for disease. Coexistent V PNS was common, highlighting the need to examine V branches to allow complete treatment planning. The unique radiological patterns identified showcases disease progression. As early detection improves patient outcomes, the radiologist must look for peripheral VII involvement in specific anatomical areas, which is within the capabilities of 3T MR neurography.

Deep spatial-omics analysis of Head & Neck carcinomas provides alternative therapeutic targets and rationale for treatment failure.

Immune checkpoint inhibitor (ICI) therapy has had limited success (<30%) in treating metastatic recurrent Head and Neck Oropharyngeal Squamous Cell Carcinomas (OPSCCs). We postulate that spatial determinants in the tumor play a critical role in cancer therapy outcomes. Here, we describe the case of a male patient diagnosed with p16+ OPSCC and extensive lung metastatic disease who failed Nivolumab and Pembrolizumab/Lenvatinib therapies. Using advanced integrative spatial proteogenomic analysis on the patient's recurrent OPSCC tumors we demonstrate that: (i) unbiased tissue clustering based on spatial transcriptomics (ST) successfully detected tumor cells and enabled the investigation of phenotypic traits such as proliferation or drug-resistance genes in the tumor's leading-edge and core; (ii) spatial proteomic imagining used in conjunction with ST (SpiCi, Spatial Proteomics inferred Cell identification) can resolve the profiling of tumor infiltrating immune cells, (iii) ST data allows for the discovery and ranking of clinically relevant alternative medicines based on their interaction with their matching ligand-receptor. Importantly, when the spatial profiles of ICI pre- and post-failure OPSCC tumors were compared, they exhibited highly similar PD-1/PD-L1low and VEGFAhigh expression, suggesting that these new tumors were not the product of ICI resistance but rather of Lenvatinib dose reduction due to complications. Our work establishes a path for incorporating spatial-omics in clinical settings to facilitate treatment personalization.

Patterns of spread and anatomical prognostic factors of pre-auricular cutaneous squamous cell carcinoma extending to the temporal bone.

BACKGROUND: Improvements can be made in the management and staging of advanced pre-auricular cutaneous squamous cell carcinoma (cSCC). We aimed to analyze radiological patterns of spread and clinico-anatomical prognostic factors. METHODS: Retrospective review of 54 patients with pre-auricular cSCC (cutaneous/nodal) who underwent temporal bone resection with curative intent. RESULTS: Involvement of the cartilaginous external auditory canal (EAC) (79.6%) and retromandibular space (63.0%) was common. Styloid process/anterior carotid sheath (ACS) (11.1%) and bony EAC (7.4%) involvement were rare. ACS involvement resulted in high rates of involved surgical margins (100%) and poor outcomes on univariable analysis. Negative prognostic factors on multivariable analysis included salvage surgery and invasion of the bony EAC, mandible, pterygoid muscle(s), and dura. CONCLUSION: The bony EAC and ACS can form temporary barriers to tumor spread, with the latter representing a potential limit of resectability. Prognostic factors revealed can lead to the development of a more appropriate staging tool.

Development of an in vivo murine model of perineural invasion and spread of cutaneous squamous cell carcinoma of the head and neck.

Introduction: Cutaneous squamous cell carcinoma of the head and neck (cSCCHN) can metastasize by invading nerves and spread toward the central nervous system. This metastatic process is called perineural invasion (PNI) and spread (PNS). An in vivo sciatic nerve mouse model is used for cSCCHN PNI/PNS. Here we describe a complementary whisker pad model which allows for molecular studies investigating drivers of PNI/PNS in the head and neck environment. Methods: A431 cells were injected into the whisker pads of BALB/c Foxn1nu and NSG-A2 mice. Tumor progression was monitored by bioluminescence imaging and primary tumor resection was performed. PNI was detected by H&E and IHC. Tumor growth and PNI were assessed with inducible ablation of LOXL2. Results: The rate of PNI development in mice was 10%-28.6%. Tumors exhibited PNI/PNS reminiscent of the morphology seen in the human disease. Our model's utility was demonstrated with inducible ablation of LOXL2 reducing primary tumor growth and PNI. Discussion: This model consists in a feasible way to test molecular characteristics and potential therapies, offers to close a gap in the described in vivo methods for PNI/PNS of cSCCHN and has uses in concert with the established sciatic nerve model.

Fascial layers encountered in the lateral skull base region: A cadaveric and radiological analysis.

BACKGROUND: In our experience, the anterior carotid sheath forms an important plane of dissection when excising temporal bone region cancers. However, its anatomical composition, relationships, and radiological appearance remains unclear. METHODS: Eight sides of cadaveric heads were dissected. Anatomical findings were correlated with a high-resolution baseline T1 MRI. RESULTS: The anterior carotid sheath was formed by the tensor-vascular-styloid fascia, stylopharyngeal fascia, buccopharyngeal fascia (BPF), and longus capitis fascia (LCF), and appeared as a hypointense line on MRI. Not previously described, the glossopharyngeal nerve pierced the sheath 9.0 mm (SD 2.1 mm) below the skull base and traveled through its LCF and BPF layers to exit near the pharynx. CONCLUSION: Multiple fascial layers formed the anterior carotid sheath at the skull base, and this was radiologically identifiable. Further studies are required to validate findings and investigate the role this fascial plane has in forming an effective barrier to spread of malignancy.

Epidemiology and treatment outcomes of cutaneous squamous cell carcinoma extending to the temporal bone.

BACKGROUND: Accurate epidemiological and outcomes data regarding cutaneous squamous cell carcinoma (cSCC) extending to the temporal bone is lacking. METHODS: Retrospective analysis of 167 Australian patients with primary and peri-temporal bone cSCC. RESULTS: cSCC extending from secondary subsites (93.4%) was 14 times more frequent than primary temporal bone SCC (6.6%). For patients who underwent curative surgery ± post-operative radiotherapy (n = 146, 87.4%), 5-year disease-free survival, locoregional recurrence-free survival, disease-specific survival, and overall survival was 53.0%, 59.4%, 67.9%, and 44.7%, respectively. External ear and pre-auricular tumors, salvage surgery, tumor size (≥40 mm medial-lateral), nodal disease, and involved margins were negative predictors of survival in multivariable analysis. CONCLUSION: In regions of high sun exposure, cSCCs extending to the temporal bone are more common than primary cancers. Outcomes are improved with clear margins, justifying the need for radical resection. Further research regarding pre-auricular cancers is required given poorer associated survival outcomes.

Facial nerve perineural spread from cutaneous squamous cell carcinoma of the head and neck: A single institution analysis of epidemiology, treatment, survival outcomes, and prognostic factors.

BACKGROUND: This study aimed to examine patients with facial nerve (VII) perineural spread (PNS) from cutaneous squamous cell carcinoma of the head and neck. METHODS: Retrospective analysis of patients managed by an Australian tertiary center between 2000 and 2019. RESULTS: Seventy three patients were included. Most presented with recurrent disease (89.0%) and simultaneous trigeminal nerve (V) involvement (67.1%). Of the 55 patients (75.3%) who received curative intent treatment, 48 received surgery plus/minus post-operative radiotherapy. In these patients, 5-year disease-free survival, disease-specific survival, and overall survival was 50.7%, 68.7%, and 58.1%, respectively. Pathological nodal disease, involved margins, increasing VII zonal extent, and concurrent zone 2 V PNS significantly worsened outcomes. CONCLUSION: High rates of recurrent disease reflects the importance of adequate treatment of the primary. Surgery and post-operative radiotherapy remains the mainstay treatment. Outcomes are improved in early-stage disease and with clear surgical margins, reinforcing the need for prompt diagnosis and intervention.

Sexual debut and association with oral human papillomavirus infection, persistence and oropharyngeal cancer-An analysis of two Australian cohorts.

Oropharyngeal cancer is increasingly caused by human papillomavirus (HPV), and this increase is believed to be caused by changing sexual behaviour. It has been hypothesised that an immune response to HPV through sexual intercourse is much stronger than an immune response elicited from oral sex. Therefore, people who have their debut of oral sex before or at the same time as sexual intercourse would have a weaker immune response to HPV and hence be more likely to develop a persistent oral HPV infection and oropharyngeal cancer. Drake et al (Cancer. 2021;127[7]:1029-1038) found some evidence that supported this hypothesis. We have reanalysed two of our Australian cohorts with similar data in order to provide a perspective of Drake and colleagues' publication, as sexual behaviour varies depending on culture and geographical location. We found that engaging in oral sex (OR 4.46, 95% CI [1.88-10.62]) and being younger than 20 years at oral sex debut (OR 9.46, 95% CI [3.53-25.31]) were both very strong risk factors for oropharyngeal cancer. Participants in the general population cohort who had their sexual intercourse debut before the age of 18 were more likely to be oral HPV positive (OR 2.69, 95% CI [1.50-4.83]). Oral sex debut before sexual intercourse debut was quite uncommon in our two Australian cohorts. However, timing of or sexual debuts may further add to risks of oropharyngeal cancer, and future studies should be designed to investigate timing and order of sexual debuts to help clarify the roles of these potential causal factors.

Immunotherapy for the treatment of perineural spread in cutaneous head and neck squamous cell carcinoma: Time to rethink treatment paradigms.

BACKGROUND: Immune checkpoint inhibitors have shown promising antitumour activity. Application in head and neck cutaneous squamous cell carcinoma (cSCC) large nerve perineural spread (PNS) is limited. METHODS: Retrospective review of 13 patients with PNS receiving anti-PD-1 therapy from September 2017 to May 2021 is presented. Primary endpoints were objective response (complete or partial response) and median time to progression, determined by Head and Neck Multi-Disciplinary Team (MDT) and independent radiology review of magnetic resonance imaging (MRI) and/or computed tomography/positron emission tomography (CT/PET). RESULTS: Objective response was observed in 9/13 patients (69%), with complete response in 6 (46%) and partial response in 3 patients (23%). Median time to response was 2.1 months (IQR 1.8-2.7 months). There were 3 (23%) patients with progressive disease, with median time to progression of 3.5 months. There were no grade 3-4 treatment related adverse events. CONCLUSIONS: This case series supports developing evidence for anti-PD-1 checkpoint inhibitor therapy for perineural spread, supporting future prospective clinical trials in this patient population.

Human papillomavirus infection and tumor microenvironment are associated with the microbiota in patients with oropharyngeal cancers-pilot study.

BACKGROUND: Previous microbiome studies of oropharyngeal cancer have shown that there are differences in the oral microbiota between human papillomavirus (HPV)-positive and HPV-negative patients. METHODS: We collected saliva, normal tissue, and tumor biopsies from 13 patients with oropharyngeal cancer (eight HPV-positive, five HPV-negative). We obtained basic clinical data from each patient. Extracted DNA was 16S rRNA gene sequenced. Analysis was based on HPV status and sample site using univariate, multivariate, and mixed effect regression methods. RESULTS: Multivariate analysis methods separated samples based on HPV status (Adonis, p < 0.001). Comparison of patients showed that there were significant changes in microbial richness across all sites based on HPV status (linear mixed effects regression, p = 0.0002). CONCLUSIONS: We found significant differences in overall microbial community and bacterial richness between oropharyngeal patients based on HPV status. Our results suggest that there are significant differences in the microbiome in patients with oropharyngeal cancer based on HPV status.

Evolution of Cancer Vaccines-Challenges, Achievements, and Future Directions.

The development of cancer vaccines has been intensively pursued over the past 50 years with modest success. However, recent advancements in the fields of genetics, molecular biology, biochemistry, and immunology have renewed interest in these immunotherapies and allowed the development of promising cancer vaccine candidates. Numerous clinical trials testing the response evoked by tumour antigens, differing in origin and nature, have shed light on the desirable target characteristics capable of inducing strong tumour-specific non-toxic responses with increased potential to bring clinical benefit to patients. Novel delivery methods, ranging from a patient's autologous dendritic cells to liposome nanoparticles, have exponentially increased the abundance and exposure of the antigenic payloads. Furthermore, growing knowledge of the mechanisms by which tumours evade the immune response has led to new approaches to reverse these roadblocks and to re-invigorate previously suppressed anti-tumour surveillance. The use of new drugs in combination with antigen-based therapies is highly targeted and may represent the future of cancer vaccines. In this review, we address the main antigens and delivery methods used to develop cancer vaccines, their clinical outcomes, and the new directions that the vaccine immunotherapy field is taking.

Malignancies requiring temporal bone resection: An Australian single-institution experience.

BACKGROUND: Malignancies in and around the temporal bone are aggressive and difficult to manage. In Queensland (Australia), where skin cancer rates are exceedingly high, tumours extending to the temporal bone from surrounding structures occur more commonly than primary cancers. Yet, a paucity of evidence exists as to their management and outcomes. This study aimed to review an Australian centre's experience of managing temporal and peritemporal bone malignancies, reporting on patient and tumour characteristics, treatment, and survival outcomes. METHODS: Retrospective analysis of patients with primary temporal bone cancer and cancers extending to the temporal bone managed by the Queensland Skull Base Unit (Princess Alexandra Hospital) between 2000 and 2019. RESULTS: A total of 222 patients were identified, of which 203 (91.4%) had cutaneous primaries, with 167 (75.2%) being squamous cell carcinoma (SCC). 73.9% presented with locoregionally recurrent or residual disease. Secondary tumours (92.8%) were 12 times more frequent than primary malignancies (7.2%), with the preauricular subsite the most common (45.5%). In the 201 patients (90.5%) who underwent curative intent surgery, 5-year overall survival, disease-free survival (DFS), and disease-specific survival was 46.6%, 52.2%, and 65.9%, respectively. The preauricular subsite (p = 0.004), melanoma (vs. SCC, p = 0.027), involved margins (p < 0.001), and pathologically involved nodes (p < 0.001) were associated with significantly worse DFS. CONCLUSION: This is one of the largest studies of temporal bone malignancy in the literature, comprised primarily of secondary cutaneous malignancies. Although clear differences in epidemiological characteristics exist around the world, survival remains poor. Treatment should focus on achieving a clear margin of resection to optimize outcomes.

Complete response to PD-1 blockade following EBV-specific T-cell therapy in metastatic nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) is an Epstein-Barr virus (EBV)-associated heterogeneous disease and is characterized by peritumoral immune infiltrate. Adoptive T-cell therapy (ACT) has emerged as a potential therapeutic strategy for NPC. However, the tumor microenvironment remains a major roadblock for the successful implementation of ACT in clinical settings. Expression of checkpoint molecules by malignant cells can inhibit the effector function of adoptively transferred EBV-specific T cells. Here we present a novel case report of a patient with metastatic NPC who was successfully treated with a combination of EBV-specific ACT and programmed cell death-1 blockade therapy. Following combination immunotherapy, the patient showed complete resolution of metastatic disease with no evidence of disease relapse for 22 months. Follow-up immunological analysis revealed dramatic restructuring of the global T-cell repertoire that was coincident with the clinical response. This case report provides an important platform for translating these findings to a larger cohort of NPC patients.

Adenoid cystic carcinoma: a review of clinical features, treatment targets and advances in improving the immune response to monoclonal antibody therapy.

The natural history of adenoid cystic carcinoma (ACC) is relentless, defined by treatment failure heralded by locoregional recurrence and distant metastatic disease. In this review, we present an update of clinical features, molecular classification, current targeted therapies, immune landscapes and novel treatment targets with their respective clinical trials. The presented results are defined by a lack of overall response rate and limited progression free survival, with restriction to stable disease. In addition, ACC is resistant to immune checkpoint inhibition due to low tumour immunogenicity and lack of PD-L1 expression. Here we present a new prospective research paradigm for ACC, including the potential to target prostate specific membrane antigen (PSMA) and the potential for manipulation of target receptors in the clinic. The presentation of this review aims to promote future research to improve response rates and outcomes for therapeutics undergoing clinical trial in ACC.

The importance of smoking status at diagnosis in human papillomavirus-associated oropharyngeal cancer.

BACKGROUND: Smoking status at point of diagnosis is not used in defining risk groups for human papillomavirus (HPV)-associated oropharyngeal cancer (OPC) despite its prognostic value in head and neck cancer. METHODS: Retrospective analysis of consecutive patients treated with chemoradiotherapy between January 2005 and July 2017 was performed with multivariable analysis to explore the impact of smoking status at diagnosis (current/former/never) on overall survival (OS), cancer-specific survival (CSS) and progression-free survival (PFS). RESULTS: Median follow-up was 61 months. Four hundred and four patients were included. Current smokers had inferior OS versus never and former smokers [adjusted HR 2.37 (95% CI 1.26-4.45, p < 0.01) and 2.58 (95% CI 1.40-4.73, p < 0.01), respectively] and inferior PFS versus never smokers [adjusted HR 1.83 (95% CI 1.00-3.35, p = 0.04)]. Smoking status did not predict for CSS. CONCLUSION: Detailed smoking behavior should be considered in refining risk groups in HPV-associated OPC treated with radiotherapy and in future trial design eligibility and stratification.

Therapeutic implications of immune-profiling and EGFR expression in salivary gland carcinoma.

BACKGROUND: Data relating to the efficacy of immune checkpoint inhibitors (ICI) for salivary gland carcinomas (SGC) is gradually evolving with responses varying among different histotypes. To address these disparities, this retrospective analysis examined the prevalence of recognized biomarkers of response to ICI; namely programmed death-1 (PD-1), programmed death-ligand 1 (PD-L1), combined positive score (CPS), epidermal growth factor receptor (EGFR), and microsatellite instability (MSI) in patients with SGC with an aim to determine any prognostic or survival benefits and stratify the use of ICI in this disease. PATIENTS AND METHODS: Of 52 patients with primary SGC eligible for this study, the most common histological types were adenoid cystic carcinoma (n = 17, 33%), salivary duct carcinoma (n = 14, 27%), mucoepidermoid carcinoma (n = 11, 21%), and acinic cell carcinoma (n = 6, 11%). Immunohistochemistry (IHC) was performed using the Ventana Discovery Ultra auto-staining platform for EGFR, PD-1, PD-L1, and mismatch repair (MMR) proteins. CPS ≥1 defined PD-L1 positive cases and log-rank testing was performed to examine the relationship between PD-L1 expression status and disease-free survival (DFS) and overall survival (OS). RESULTS: CPS positivity was seen in 9 (17.3%) patients, none of which were adenoid cystic carcinoma. All 52 (100%) cases expressed retained MMR proteins inferring microsatellite stability (MSS) and EGFR expression was identified in 45 of 52 (86.5%) patients. CPS positivity (score ≥1) was significantly associated with advanced pathological T status (P = .021), advanced pathological N status (P = .006), high histological tumor grade (P = .045), and positive histological margin (P = .023). Patients with PD-L1 positivity in tumor cells did not have an inferior 3-year OS (P = .93). CONCLUSION: The data from this retrospective study highlighting the uniform microsatellite stability alongside the low prevalence of CPS positivity suggests that only a minority of SGC patients may benefit from ICI therapy alone. The high rates of EGFR expression in SGC may be a target to augment immune checkpoint therapy response.