Primary cSCC Research Articles

Stathmin 1 and p53 Expression in Cutaneous Squamous Cell Carcinoma and Precursor Lesions.

Studies on the relationship between stathmin 1 (STMN1) and cutaneous squamous cell carcinoma (cSCC) are limited. We aimed to evaluate the relationship between clinicopathological factors and STMN1 and p53 expressions in cSCC and compare them with those in the precursor lesions of cSCC and normal tissue. A total of 195 patients, followed between January 2014 and December 2021, with diagnoses of primary cSCC (n = 129), in situ cSCC (n = 20), or actinic keratosis (n = 46), as well as 29 histopathologically normal tissue samples, were included in the study. Immunohistochemical staining for STMN1 and p53 was performed. In the cSCC group, STMN1 scores were higher in poorly differentiated ( P = 0.001) and ulcerated ( P < 0.001) tumors. A linear relationship between STMN1 score and tumor area, tumor thickness, and mitosis was found ( P = 0.001, P = 0.003, and P < 0.001, respectively). There was no statistically significant correlation between STMN1 and p53 scores. Our results support the previous view that STMN1 may be associated with some adverse clinicopathological and high-risk features of cSCC. To the best of our knowledge, this is the first and largest study to investigate STMN1 expression in cSCC, precancerous lesions of cSCC, and normal tissues.

Understanding the squamous cell carcinoma immune microenvironment.

Primary cutaneous squamous cell carcinoma (cSCC) is the second most common human cancer with a rising incidence of about 1.8 million in the United States annually. Primary cSCC is usually curable by surgery; however, in some cases, cSCC eventuates in nodal metastasis and death from disease specific death. cSCC results in up to 15,000 deaths each year in the United States. Until recently, non-surgical options for treatment of locally advanced or metastatic cSCC were largely ineffective. With the advent of checkpoint inhibitor immunotherapy, including cemiplimab and pembrolizumab, response rates climbed to 50%, representing a vast improvement over chemotherapeutic agents used previously. Herein, we discuss the phenotype and function of SCC associated Langerhans cells, dendritic cells, macrophages, myeloid derived suppressor cells and T cells as well as SCC-associated lymphatics and blood vessels. Possible role(s) of SCC-associated cytokines in progression and invasion are reviewed. We also discuss the SCC immune microenvironment in the context of currently available and pipeline therapeutics.

HLA expression as a risk factor for metastases of cutaneous squamous-cell carcinoma in organ- transplant recipients

BackgroundSolid organ-transplant recipients (SOTR) have an increased risk of cutaneous squamous-cell carcinoma (cSCC), metastasis and death from cSCC. In immunocompetent patients with mucosal SCC, downregulation of HLA class I is associated with poor prognosis. Since the degree of HLA expression on tumor cells could play a role in immunogenicity and pathophysiology of cSCC metastasis, we hypothesized that decreased HLA expression is associated with an increased risk of metastasis. MethodsWe compared HLA expression between primary metastasized cSCCs, their metastases, and non-metastasized cSCCs from the same patients. Samples were stained for HLA-A, HLA-B/-C and quantified by calculating the difference in immunoreactivity score (IRS) of the primary cSCC compared with all non-metastasized cSCCs. ResultsThe mean IRS score for HLA-B/C expression was 2.07 point higher in metastasized compared to non-metastasized cSCCs (p = 0.065, 95 % CI −0.18–4.32). 83.3 % of the primary metastasized cSCCs had an IRS score of 4 or higher, compared to 42.9 % in non-metastasized cSCCs. Moderately to poorly differentiated cSCCs had more HLA class I expression compared to well-differentiated cSCCs. ConclusionContrary to immunocompetent patients, HLA-B/C expression tends to be upregulated in metastasized cSCC compared to non-metastasized cSCC in SOTR, suggesting that different tumor escape mechanisms play a role in SOTR compared to immunocompetent patients.

466 Cancer-associated fibroblast activation predicts progression, metastasis and prognosis of cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) possesses metastatic potential and in metastatic case the prognosis is poor. At present, there are no established biomarkers for assessment of metastasis risk or prognosis of primary cSCC. Cancer-associated fibroblasts (CAFs) promote the progression of cancer, but there is limited evidence of their role in cSCC. Here, we have examined the potential of CAF markers in the assessment of metastasis risk and prognosis of cSCC. We used multiplexed fluorescence immunohistochemistry to profile CAF landscape in metastatic and non-metastatic primary human cSCCs, actual metastases, and in premalignant and benign epidermal lesions.

Selected Articles from This Issue

α-FR is overexpressed in a variety of solid tumors, including high-grade serous ovarian cancer, triple-negative breast cancer, and non–small cell lung cancer. CT900 is a small molecule thymidylate synthase (TS) inhibitor that binds to and is taken up by α-FR. Banerjee and colleagues report results from the first clinical trial to show reproducible single agent responses caused by a small molecule in α-FR-overexpressing cancers. The toxicity profile did not show classical TS inhibitor toxicity such as myelosuppression suggesting differential α-FR mediated uptake in tumor tissue. This trial is proof of concept for developing α-FR targeting small molecules, which are selectively taken up in α-FR-overexpressing tumors for patient benefit and are an alternate approach to antibody drug conjugates that already target α-FR.Immune checkpoint inhibitors (ICI) have modest efficacy in patients with mucosal melanoma. Although PD-1/PD-L1 monotherapy has limited benefit, combined therapy with CTLA4 and PD-1 inhibitors improves response rates but increases toxicity. VEGF is highly expressed in melanoma and contributes to progression. Combined treatment with ICI and VEGF inhibitors has shown positive outcomes across various cancer types. Here, Mao and colleagues present the results of a phase II study evaluating the PD-L1 inhibitor atezolizumab and the VEGF inhibitor bevacizumab as first-line therapy in Chinese patients with advanced mucosal melanoma. Over a median follow-up of 13.4 months, the objective response rate was 45.0% in 40 evaluable patients. Atezolizumab in combination with bevacizumab showed promising efficacy and manageable safety. This study sheds light on the dual strategy of VEGF and PD-L1 inhibition in patients with this rare melanoma subtype, for whom prognosis is otherwise generally poor.Defining the immune mechanisms responsible for early control of tumors is critical for guiding treatment strategies. Ferguson and colleagues applied imaging mass cytometry to map the immune landscape and identify differences in immune populations and their specific interactions between high-risk primary cSCC tumors that did not progress and those that developed metastases. The study also reveals that the immunosuppressive state alters the cellular composition of primary tumors. The ability to predict metastatic tumor progression at the time of initial diagnosis of primary cSCC will aid personalized medical care and better disease surveillance.Using publicly available genome-wide genetic dependency maps, Grubb and colleagues sought lineage-enriched anticancer targets. In kidney cancer, this strategy identified BCL2L1 which encodes the antiapoptotic BCL-XL protein as a candidate. Relying on cell-based apoptosis assays, in vivo studies, and clinical validations, as well as using genetic and pharmacological approaches, these studies revealed that a tumor's mesenchymal cell state conferred BCL-XL dependence. The findings identify BCL-XL as a novel target in kidney cancer and present potential biomarkers to stratify renal tumors based on their reliance on BCL-XL.

Lifetime Sunburn Trajectories and Associated Risks of Cutaneous Melanoma and Squamous Cell Carcinoma Among a Cohort of Norwegian Women

To our knowledge, no study has prospectively investigated sunburn patterns over age periods from childhood to adulthood and their associations with skin cancer risk. To identify lifetime trajectories of sunburns and compare the association between these trajectories and subsequent risk of cutaneous melanoma and squamous cell carcinoma (cSCC). This population-based cohort study included participants from the Norwegian Women and Cancer Study, established in 1991, with follow-up through 2018. Baseline questionnaires were issued from 1991 to 2007, with follow-up questionnaires every 5 to 7 years. Data analysis was performed from March 16, 2021, to December 4, 2021. Participants reported pigmentation factors, sunbathing vacations, and indoor tanning. Annual frequencies of sunburns were reported for childhood, adolescence, and adulthood. Information on cancer diagnoses, emigration, and death were obtained through linkage to the Cancer Registry of Norway using the unique personal identification number of Norwegian citizens. Of the 172 472 women (age range, 31-70 years) who returned questionnaires, 169 768 received questions about sunburns at study inclusion. Five classes (stable low, low-moderate-low, low to high, high to low, and stable high) of individual lifetime sunburn trajectories with similar shapes were estimated in 3 samples up to 39 years (n = 159 773), up to 49 years (n = 153 297), and up to 59 years (n = 119 170). Mean follow-up ranged from 14.3 to 19.5 years in the 3 samples, during which 1252 to 1774 women were diagnosed with incident primary melanoma and 739 to 871 women with incident primary cSCC. With hazard ratios (HRs) and 95% CIs estimated using a Cox proportional hazards model, the stable high and high to low trajectories showed statistically significant increased melanoma and cSCC risks compared with the stable low trajectory across all samples (≤39 years for stable high and high to low trajectories: melanoma: HR, 1.50 [95% CI, 1.28-1.75] and HR, 1.44 [95% CI, 1.20-1.73]; cSCC: HR, 1.51 [95% CI, 1.22-1.87] and HR, 1.47 [95% CI, 1.14-1.91]). Other trajectories showed increased risk, though generally weaker and mainly estimates that were not statistically significant. There was no statistically significant heterogeneity between melanoma and cSCC estimates. This cohort study showed that high sunburn frequency throughout life was associated with increased melanoma and cSCC risk. Furthermore, sunburns in childhood are especially important for subsequent risk of these skin cancers. Avoiding sunburns throughout life, in particular in childhood, is therefore crucial.

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

Accurate epidemiological and outcomes data regarding cutaneous squamous cell carcinoma (cSCC) extending to the temporal bone is lacking. Retrospective analysis of 167 Australian patients with primary and peri-temporal bone cSCC. 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. 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.

35334 Clinical usage data demonstrates appropriate use of the prognostic 40-gene expression profile (40-GEP) test for cutaneous squamous cell carcinoma with one or more risk factors

Although the overall metastatic rate for cutaneous squamous cell carcinoma (cSCC) is low, because the incidence exceeds a million cases per year, deaths from this disease are estimated to surpass those from melanoma. The risk of poor outcomes guides patient management decisions, therefore accurate risk assessment is critical. Risk assessment occurs through weighting of clinicopathologic risk factors by physician judgement and/or through staging systems (e.g. AJCC staging). The 40-gene expression profile (40-GEP) test was developed and validated to accurately classify risk for regional/distant metastasis as low (Class1), moderate (Class2A), or high (Class2B) in patients with primary cSCC with one or more risk factors. The objective of this study was to report on clinicopathologic conditions leading to clinical usage of the 40-GEP. Summary metrics on the first 2000 clinical cases received that met testing criteria were generated by a review of the clinical requisition form. Risk factors included location on the H or M area, ≥2cm diameter, poorly defined borders, patient immunosuppression, rapidly growing tumor, site of prior radiation or chronic inflammation, high-risk subtype, invasion beyond the subcutaneous fat, poor differentiation, lymphovascular invasion, and perineural invasion. In this clinically tested cohort, the technical reliability of the test was 96.8%. Lesions submitted for testing had 1-2 (50.3%), 3-6 (47.3%), or 7+ (2.4%) risk factors (average of 2.8). The intended use population aligns with cases submitted for clinical testing suggesting that physicians understand appropriate use of molecular prognostic testing. Incorporating 40-GEP test results may support risk-appropriate surveillance and treatment decisions.

Identification of metastatic primary cutaneous squamous cell carcinoma utilizing artificial intelligence analysis of whole slide images

Cutaneous squamous cell carcinoma (cSCC) harbors metastatic potential and causes mortality. However, clinical assessment of metastasis risk is challenging. We approached this challenge by harnessing artificial intelligence (AI) algorithm to identify metastatic primary cSCCs. Residual neural network-architectures were trained with cross-validation to identify metastatic tumors on clinician annotated, hematoxylin and eosin-stained whole slide images representing primary non-metastatic and metastatic cSCCs (n = 104). Metastatic primary tumors were divided into two subgroups, which metastasize rapidly (≤ 180 days) (n = 22) or slowly (> 180 days) (n = 23) after primary tumor detection. Final model was able to predict whether primary tumor was non-metastatic or rapidly metastatic with slide-level area under the receiver operating characteristic curve (AUROC) of 0.747. Furthermore, risk factor (RF) model including prediction by AI, Clark’s level and tumor diameter provided higher AUROC (0.917) than other RF models and predicted high 5-year disease specific survival (DSS) for patients with cSCC with 0 or 1 RFs (100% and 95.7%) and poor DSS for patients with cSCCs with 2 or 3 RFs (41.7% and 40.0%). These results indicate, that AI recognizes unknown morphological features associated with metastasis and may provide added value to clinical assessment of metastasis risk and prognosis of primary cSCC.

Risk factors for incomplete excision of cutaneous squamous cell carcinoma: a large cohort study.

BackgroundThe standard treatment for cutaneous squamous cell carcinoma (cSCC) is surgical excision. Failure to radically remove a cSCC is a risk for recurrence, progression and metastasis.ObjectivesThis study investigates several risk factors for incomplete excision of cSCC.MethodsAll consecutive patients in a single institution treated with wide local excision for primary cSCC over a 10‐year period were included in this study. Risk factors such as: gender, age, immunosuppression, tumour size, location, differentiation grade, tumour depth, perineural and lymphovascular invasion (PNI and LVI) were extracted from the database. Univariable and (if applicable) multivariable logistic regression analysis were used to identify risk factors (P < 0.05). Generalized estimating equations (GEEs) were used for multiple tumours within the same patients.ResultsA total of 566 patients with 1159 cSCC were identified. Univariable and multivariable logistic regression analysis showed that depth beyond the dermis (OR: 5.7 95% CI: 3.1–10.5) was the only risk factor for incomplete excision of cSCC. Immunosuppression was only a risk factor in the deep plane (OR: 2.5, 95% CI: 1.3–4.6).ConclusionTumour depth beyond the dermis is the most important risk factor for incomplete excision of cSCC. Immunosuppression is a risk factor in the deep plane but its relevance is uncertain. Immunosuppression is not consistently included in the current cSCC staging systems, but care should be taken when treating these patients.

Cancer Progression Gene Expression Profiling Identifies the Urokinase Plasminogen Activator Receptor as a Biomarker of Metastasis in Cutaneous Squamous Cell Carcinoma.

Cutaneous squamous cell carcinoma (cSCC) of the head and neck region is the second most prevalent skin cancer, with metastases to regional lymph nodes occurring in 2%–5% of cases. To further our understanding of the molecular events characterizing cSCC invasion and metastasis, we conducted targeted cancer progression gene expression and pathway analysis in non-metastasizing (PRI-) and metastasizing primary (PRI+) cSCC tumors of the head and neck region, cognate lymph node metastases (MET), and matched sun-exposed skin (SES). The highest differentially expressed genes in metastatic (MET and PRI+) versus non-metastatic tumors (PRI-) and SES included PLAU, PLAUR, MMP1, MMP10, MMP13, ITGA5, VEGFA, and various inflammatory cytokine genes. Pathway enrichment analyses implicated these genes in cellular pathways and functions promoting matrix remodeling, cell survival and migration, and epithelial to mesenchymal transition, which were all significantly activated in metastatic compared to non-metastatic tumors (PRI-) and SES. We validated the overexpression of urokinase plasminogen activator receptor (uPAR, encoded by PLAUR) in an extended patient cohort by demonstrating higher uPAR staining intensity in metastasizing tumors. As pathway analyses identified epidermal growth factor (EGF) as a potential upstream regulator of PLAUR, the effect of EGF on uPAR expression levels and cell motility was functionally validated in human metastatic cSCC cells. In conclusion, we propose that uPAR is an important driver of metastasis in cSCC and represents a potential therapeutic target in this disease.

Defining the incidence of cutaneous squamous cell carcinoma in coastal NSW Australia.

ABSTRACTBackground/ObjectivesTo describe the incidence of primary cutaneous squamous cell carcinoma in coastal NSW Australia.MethodsThe design is a case‐controlled study of reported cSCC from 2016 to 2019 within a defined region of coastal southern NSW. Participants include all reported pathological diagnoses of cSCC in patients greater than 20 years of age. The main outcome measures the incidence and relative risk of cSCC.ResultsThe age‐adjusted incidence rate of primary cSCC was 856/105/year. Men over 60 years of age had an age‐adjusted incidence rate of 2875/106/year. Histologically diagnosed invasive SCC samples were included using SNOMED clinical term codes. Keratoacanthomas and SCC in situ SNOWMED codes were not included. SCC in situ results was found within the sample analysis and was offset by including one SCC per annum per person.ConclusionsThe rates of cSCC are far higher than previously reported and demand a reappraisal of our national management of this disease.

Immune Disregulation in Cutaneous Squamous Cell Carcinoma of Patients with Recessive Dystrophic Epidermolysis Bullosa: A Single Pilot Study.

Background: Cutaneous squamous cell carcinoma (cSCC) is one of the most devastating complications of recessive dystrophic epidermolysis bullosa (RDEB). We recently demonstrated a reduction in immune cell peritumoral infiltration in RDEB patients with cSCC, together with a reduction in CD3+, CD4+, CD68+ and CD20 lymphocytes as compared to primary and secondary cSCC in patients without RDEB. Recently, new molecules, such as high mobility group box 1 (HMGB1), T cell immunoglobulin, mucin domain 3 (TIM-3) and Heme oxygenase-1 (HO-1), have been shown to play a role in antitumoral immunity. Objective: Patients with RDEB are known to be at increased risk of developing skin cancers, including the dreaded squamous cell carcinoma of the. Tendentially, cSCCs that arise in the context of EBDR are more aggressive and lead to statistically significant bad outcomes compared to cSCCs developed on the skin of patients without EBDR. In an attempt to study the microenvironment of these lesions, we conducted an immunohistochemical analysis study of proteins that could be actively involved in the genesis of this type of malignant neoplasms. Methods: In this retrospective study, the OH1-HMGB1-TIM3 activation axis, as correlated to the T lymphocytes cell count, was assessed in biopsy samples from 31 consecutive cases consisting of 12 RDEB patients with cSCC, 12 patients with primary cSCC and 7 RDEB patients with pseudoepitheliomatous cutaneous hyperplasia. Parametric Student’s t-test was applied for normally distributed values, such as CD4+ and CD8+, and non-parametric Mann–Whitney test for non-normally distributed values, such as HMGB-1, TIM-3 and HO-1. Results: In RDEB patients with cSCC and with pseudoepitheliomatous hyperplasia, the expression of CD4 T helper lymphocytes was lower than in the peritumoral infiltrate found in primary cSCC. CD8 cytotoxic T lymphocytes were increased in primary cSCC compared to the other two groups. An increased HMGB1 expression was evident in both primary and RDEB cSCC. TIM3 expression was higher in RDEB patients with cSCC compared to the other two groups. A significantly reduced immunohistochemical expression of HO-1 was evident in the tumoral microenvironment of cSCC-RDEB as compared to primary cSCC. Conclusions: These data suggest that a reduced immune cell peritumoral infiltration in RDEB patients could be responsible, in the complexity of the mechanisms of carcinogenesis and host response, of the particular aggressiveness of the cSCC of RDEB patients, creating a substrate for greater local immunosuppression, which, potentially, can “open the doors” to development and eventual metastasis by this malignant neoplasm.

Benefit from adjuvant radiotherapy according to the number of risk factors in cutaneous squamous cell carcinoma

IntroductionIndications of adjuvant radiotherapy (RT) for high-risk cutaneous squamous cell carcinoma (cSCC) are not clearly defined. We aimed to identify factors predicting relapse in cSCC patients treated with surgery or RT alone and to assess in which clinical setting adjuvant RT was beneficial in term of progression free survival (PFS). MethodsThis retrospective analysis included patients with resectable primary cSCC treated with surgery and/or RT in curative intent, managed at Centre Léon Bérard (Lyon, France) from April 2010 to September 2020. ResultsA total of 303 patients with 529 cSCC were included. 31 (5.9%) cSCC were treated with surgery and adjuvant RT. With a median follow-up of 54 (0.2–126) months, 103 (19.5%) cSCC relapsed. In multivariate analysis, the highest predictive factor of relapse in cSCC was the number of risk factors (HR = 15.110 [95% CI: 3.91–58.40] for ≥3 risk factors p < 0.001), followed by poor differentiation (HR = 4.930 [95% CI: 2.47–9.86], p < 0.001) and perineural invasion (HR = 2.442 [95% CI: 1.11–5.38], p = 0.027). For cSCC with ≥3 risk factors, PFS was significantly higher in cSCC treated with surgery and adjuvant RT compared to those treated with surgery or RT alone (the 36-month PFS was 74% [95% CI: 43–90%] and 31% [95% CI: 10–54%] respectively, p = 0.008). ConclusionAn increased number of risk factors was identified as being the highest predictive factor of relapse in cSCC. Adjuvant RT improved PFS for high-risk cSCC with ≥3 risk factors.

Signatures of EMT, immunosuppression, and inflammation in primary and recurrent human cutaneous squamous cell carcinoma at single-cell resolution.

Rationale: The recurrence of cutaneous squamous cell carcinoma (cSCC) after surgery is associated with the reprogramming of the tumor microenvironment (TME), and remains a key factor affecting its outcomes. Methods: We employed single-cell RNA sequencing (scRNA-seq) to examine the dynamic changes in epithelial cells, T cells, myeloid cells, and fibroblasts between primary and recurrent cSCC. Cell clustering, cell trajectory, cell-cell communication, and gene set enrichment analysis were used to investigate the TME heterogeneity between primary and recurrent cSCC. Gene expression differences were monitored by IHC staining. Results: We examined the immunosuppressed microenvironment in recurrent cSCC, which exhibited a T cell-excluded and SPP1+ tumor-associated macrophages (TAMs)-enriched status. In recurrent cSCC, CD8+ T cells showed high exhaustion and low inflammatory features, while SPP1+ TAMs displayed global pro-tumor characteristics, including decreased phagocytosis and inflammation and increased angiogenesis. Furthermore, the subgroups of SPP1+ TAMs harbored distinct functions. SPP1+ CD209high TAMs showed features of phagocytosis, while SPP1+ CD209low TAMs tended to have a high angiogenic ability. A subpopulation of tumor-specific keratinocytes (TSKs) showed significant epithelial-mesenchymal transition (EMT) features in recurrent cSCC, probably due to their active communication with IL7R + cancer-associated fibroblasts (CAFs). Moreover, we found that the pleiotropic growth factor/cytokine Midkine (MDK) could provoke different cell-cell interactions in cSCC with distinctive staging. In primary cSCC, MDK was highly expressed in fibroblasts and could promote their proliferation and block the migration of tumor cells, while in recurrent cSCC, the high expression of MDK in TSKs promoted their proliferation and metastasis. Conclusion: Our study provides insights into the critical mechanisms of cSCC progression, which might facilitate the development of a powerful approach for the prevention and treatment of cSCC recurrence.

Clinical Utility of the 40-Gene Expression Profile (40-GEP) Test for Improved Patient Management Decisions and Disease-Related Outcomes when Combined with Current Clinicopathological Risk Factors for Cutaneous Squamous Cell Carcinoma (cSCC): Case Series.

IntroductionWhile improvements have been made to risk assessment of cutaneous squamous cell carcinoma (cSCC) patients, there is a critical need for a uniform and more precise stratification system of their care. To address this unmet clinical need, a prognostic 40-gene expression profile (40-GEP) test has recently been developed and independently validated to show improved stratification of metastatic risk in high-risk cSCC patients compared with current staging systems.MethodsTwo cSCC cases, both male with similar patient profiles and the same staging status across two different staging systems, yet with opposing outcomes, were chosen for retrospective review of their primary biopsy using the 40-GEP test.ResultsCase 1 declined further treatment, even when presented with evidence of a small focus of cSCC found in the last layer of nonmarginal tissue obtained from Mohs micrographic surgery (MMS). Case 1 remained recurrence free, and retrospective analysis of the initial biopsy with the 40-GEP test provided a Class 1 result (low likelihood of metastasis). Case 2, even with subsequent clearing of the primary cSCC with MMS, noted another metastatic cSCC 3 months later. Case 2, after multimodal adjuvant treatments, died due to disease progression. Retrospective analysis of the initial biopsy with the 40-GEP test provided a Class 2B result (high likelihood of metastasis).ConclusionsThe cases discussed highlight the utility in 40-GEP to provide additional information to guide treatment decisions and improve outcomes. Integrating novel molecular prognostication with traditional clinicopathological risk factors can improve stratification of high-risk cSCC patients and may inform selection of risk-appropriate treatment and surveillance strategies.

Epidemiology of advanced cutaneous squamous cell carcinoma.

Cutaneous invasive squamous cell carcinoma (cSCC) most commonly presents as a typically indolent tumour with five-year cure rates of >90%. Advanced cSCC has been defined as locally advanced or metastatic (locoregional or distant) cSCC. The epidemiological data on advanced cSCC are rare due to underreporting or exclusion of cSCC from national cancer registries. Although the frequency of local recurrence has been reported, there is no clear evidence on the incidence or mortality of locally advanced cSCCs, e.g. locally infiltrating or locally recurrent cSCCs that are not further amenable to curative surgery or radiotherapy. This gap of knowledge on the epidemiology of locally advanced cSCC, highlights the need for standardisation in defining and reporting both locally advanced and metastatic cSCC. Even though metastatic cSCCs are a small part of cSCCs (3%-5%), their aggressive characteristics contribute to significant morbidity, higher mortality and are those likely to require systemic treatments. Locally recurrent and metastatic cSCC may occur more frequently in high-risk cSCCs (up to 35%). The site of metastasis involves in the vast majority the regional lymph nodes, with the head and neck lymph nodes or parotid most commonly affected. Metastasis occurs mostly within 2-3 years of the primary cSCC diagnosis. The knowledge of the incidence and prognosis of advanced cSCC and the risk stratification of patients, who may progress to advanced cSCC, emerge as pressing research areas with important implications for cost-efficiency planning and optimisation of patient care.

266 Identification of metastatic primary cutaneous squamous cell carcinoma using artificial intelligence analysis of whole slide images

Cutaneous squamous cell carcinoma (cSCC) possesses metastatic potential and causes significant mortality. However, clinical assessment of metastasis risk of primary cSCC is challenging. In this study, we have used artificial intelligence (AI) algorithm to identify primary cSCCs with risk for metastasis. Residual neural network-architectures were trained and fine-tuned on tumor tiles extracted from clinician annotated, hematoxylin and eosin (HE)-stained whole slide images representing primary metastatic (n=45) and non-metastatic (n=59) cSCCs.

Sentinel lymph node biopsy in high-risk cutaneous squamous cell carcinoma of the head and neck

Cutaneous squamous cell carcinoma (cSCC) shows malignant behaviour in 3-4% of patients with locoregional metastases and a poor prognosis, metastases that are difficult to predict clinically. Therefore, sentinel lymph node biopsy (SLNB) has been assessed, with contradictory findings thus far. We aimed to clarify the prognostic value of SLNB in high-risk cSCC patients. We completed a retrospective clinical study amongst 63 patients, preoperatively classified as N0 with a high-risk primary cSCC of the head and neck who underwent SLNB between 2001 and 2014 at Helsinki University Hospital (Finland). Considered high risk, the inclusion criteria comprised at least two of the following characteristics: tumour diameter ≥10mm and/or thickness ≥4mm and a specific tumour location, such as the lips, ear, scalp and central face. Patients were followed-up postoperatively for a median of 4.1 years (0.2-13.8 years). Only four (6.3%) patients had positive sentinel nodes. One of these patients died of cSCC, while the other three ultimately survived their disease. Five (7.9%) patients showed a negative SLNB, but developed recurrence within one year postoperatively. Recurrence appeared in the neck lymph nodes concurrently with locoregional soft-tissue invasion in all patients. Amongst these patients, three died for cSCC and the remaining two from other causes. Comparing the SLNB-positive and SLNB-negative groups with recurrence, we identified no significant differences in terms of patient or tumour characteristics. SLNB appears to carry no prognostic value for identifying recurrent disease amongst high-risk cSCC in the head and neck area.

Mismatch Repair Protein Expression and Microsatellite Instability in Cutaneous Squamous Cell Carcinoma.

There exist relatively sparse and conflicting data on high-level microsatellite instability (MSI-H) and deficient mismatch repair (dMMR) in cutaneous malignancies. We aimed to determine the expression profiles of MMR proteins (MSH2, MSH6, MLH1, and PMS2) in different progression stages of cutaneous squamous cell carcinoma (cSCC, 102 patients in total) by immunohistochemistry, and search for MSI-H in patients with low-level MMR or dMMR using multiplex-PCR. Low-level MMR protein expression was observed in five patients: One patient with primary cSCC < 2 mm thickness and low-level MLH1, three patients with primary cSCC > 6 mm (including one with low-level MSH2, as well as MSH6 expression, and two with low-level PMS2), and one patient with a cSCC metastasis showing low-level MSH2 as well as MSH6. Intergroup protein expression analysis revealed that MLH1 and MSH2 expression in actinic keratosis was significantly decreased when compared to Bowen’s disease, cSCC < 2 mm, cSCC > 6 mm, and cSCC metastasis. In cases with low-level MMR, we performed MSI-H tests revealing three cases with MSI-H and one with low-level MSI-L. We found low-level MMR expression in a small subset of patients with invasive or metastatic cSCC. Hence, loss of MMR expression may be associated with tumour progression in a small subgroup of patients with non-melanoma skin cancer.