Immune Checkpoint Blockade in Advanced Cutaneous Squamous Cell Carcinoma: What Do We Currently Know in 2020?

The Tumor Stroma of Squamous Cell Carcinoma: A Complex Environment That Fuels Cancer Progression

The tumor microenvironment (TME), a complex assembly of cellular and extracellular matrix (ECM) components, plays a crucial role in driving tumor progression, shaping treatment responses, and influencing metastasis. This narrative review focuses on the cutaneous squamous cell carcinoma (cSCC) tumor stroma, highlighting its key constituents and their dynamic contributions. We examine how significant changes within the cSCC ECM-specifically, alterations in fibronectin, hyaluronic acid, laminins, proteoglycans, and collagens-promote cancer progression, metastasis, and drug resistance. The cellular composition of the cSCC TME is also explored, detailing the intricate interplay of cancer-associated fibroblasts (CAFs), mesenchymal stem cells (MSCs), endothelial cells, pericytes, adipocytes, and various immune cell populations. These diverse players modulate tumor development, angiogenesis, and immune responses. Finally, we emphasize the TME's potential as a therapeutic target. Emerging strategies discussed in this review include harnessing the immune system (adoptive cell transfer, checkpoint blockade), hindering tumor angiogenesis, disrupting CAF activity, and manipulating ECM components. These approaches underscore the vital role that deciphering TME interactions plays in advancing cSCC therapy. Further research illuminating these complex relationships will uncover new avenues for developing more effective treatments for cSCC.

Skin cancer prevention - Recent advances and unmet challenges

Cutaneous squamous cell carcinoma (cSCC) is the second most common malignancy in the world. Among many identified risk factors, immunosuppression is a major factor that contributes to cSCC development. Organ transplant recipients (OTRs) are at markedly increased risk of developing multiple cSCCs with a propensity for advanced metastatic disease, leading to significant morbidity and mortality. The severity of the cSCC phenotype in OTRs highlights the urgent need to identify effective preventive modalities in this population. Despite recent advances in skin cancer prevention (e.g., nicotinamide) and treatment (e.g., immune checkpoint blockade), these modalities have limited utility in OTRs due to the lack of efficacy or significant side effect. Topical treatments against precancerous skin lesions, actinic keratosis (AK), remain the primary strategy to prevent cSCC in OTRs, which also have significant deficiencies in this population. Herein, we review the epidemiology, risk factors, and current cSCC prevention strategies. We highlight the gaps and future clinical strategies to address cSCC risk in high-risk populations.

Update on the Molecular Pathology of Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer, originating from keratinocytes of the spinous layer. Numerous risk factors have been discovered for the initiation and growth of this type of cancer, such as exposure to UV and ionizing radiation, chemical carcinogens, the presence of immunosuppression states, chronic inflammation, infections with high-risk viral strains, and, last but not least, the presence of diseases associated with genetic alterations. The important socio-economic impact, as well as the difficulty associated with therapy for advanced forms, has made the molecular mechanisms underlying this neoplasia more and more intensively studied, with the intention of achieving a better understanding and advancing the treatment of this pathology. This review aims to provide a brief foray into the molecular, genetic, and epigenetic aspects of this cancer, as well as the treatment methods, ranging from the first used to the latest targeted therapies.

[Cutaneous squamous cell carcinoma of the head and neck]

OBJECTIVE

Cutaneous squamous cell carcinoma (cSCC), predominantly located on the scalp and face, is the second most prevalent skin cancer globally. Due to the increasing elderly population and rising incidence of cSCC, it has been gaining relevance in otorhinolaryngology.

MATERIAL AND METHODS

This review article is based on a selective PubMed literature search, German and European guidelines and the clinic's own experience.

RESULTS

In addition to chronic UV exposure, a disruption of the body's own immune system is becoming increasingly important. Vertical tumor thickness is associated with the highest risk of metastatic spread and local recurrence. Other significant risk factors are: horizontal tumor diameter, dedifferentiation, desmoplasia, perineural growth and localization on the face. Most cases are manageable by local excision with histological control of the excision margins. If regional metastases are clinically suspected, the draining cervical lymph node levels should be dissected depending on primary tumor location. cSCC of the upper face and the auricle primarily metastasize to the parotid gland. With the approval of the PD-1-blocking antibody cemiplimab in Europe, an active ingredient has been made available for the treatment of advanced cSCC where surgery or radiotherapy are no longer an option.

CONCLUSIONS

The otherwise very low mortality rate of cSCC increases considerably with metastases. Therefore, imaging, surgical therapy and follow-up intervals should be based on risk factors. This allows early detection of metastases or local recurrences and improves the prognosis.

Tri-Site Academic Center Experience with Immunotherapy for Metastatic Skin Cancer in Solid Organ Transplant Patients

OBJECTIVES

Organ transplant recipients have an increased risk of skin cancer, but treatment options for metastatic skin cancer are limited because of their immunosuppressed state. We sought to qualify the clinical experience and patient safety of immune checkpoint inhibitors (ICIs) for skin cancer treatment in transplant recipients at one large academic institution.

METHODS

We conducted a retrospective chart review including patients who had at least one organ transplant, a diagnosis of skin cancer, and received an ICI to treat their skin cancer.

RESULTS

Four patients met our criteria. Three received an ICI for metastatic melanoma and died secondary to their cancer. One patient, treated for squamous cell carcinoma, had remission of his cancer with ICI treatment. Only one patient had transplant rejection.

CONCLUSIONS

ICIs can be used in organ transplant patients, but the risk of transplant rejection must be carefully discussed because it may be associated with an increased risk of death. A higher risk of rejection exists with anti-programmed cell death 1 and anti-programmed cell death ligand 1 inhibitors.

Galectin-7 reprograms skin carcinogenesis by fostering innate immune evasive programs

Non-melanoma skin cancer (NMSC) has risen dramatically as a result of chronic exposure to sunlight ultraviolet (UV) radiation, climatic changes and clinical conditions associated with immunosuppression. In spite of considerable progress, our understanding of the mechanisms that control NMSC development and their associated molecular and immunological landscapes is still limited. Here we demonstrated a critical role for galectin-7 (Gal-7), a β-galactoside-binding protein preferentially expressed in skin tissue, during NMSC development. Transgenic mice (Tg46) overexpressing Gal-7 in keratinocytes showed higher number of papillomas compared to WT mice or mice lacking Gal-7 (Lgals7^-/-) when subjected to a skin carcinogenesis protocol, in which tumor initiator 7,12-dimethylbenz[a]anthracene (DMBA) and tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA) were sequentially administered. RNAseq analysis of Tg46 tumor lesions revealed a unique profile compatible with cells of the myelomonocytic lineage infiltrating these tumors, an effect that was substantiated by a higher number of CD11b⁺Gr1⁺ cells in tumor-draining lymph nodes. Heightened c-Met activation and Cxcl-1 expression in Tg46 lesions suggested a contribution of this pathway to the recruitment of these cells. Remarkably, Gal-7 bound to the surface of CD11b⁺Ly6C^hiLy6G^lo monocytic myeloid cells and enhanced their immunosuppressive activity, as evidenced by increased IL-10 and TGF-β₁ secretion, and higher T-cell inhibitory activity. In vivo, carcinogen-treated Lgals7^-/- animals adoptively transferred with Gal-7-conditioned monocytic myeloid cells developed higher number of papillomas, whereas depletion of these cells in Tg46-treated mice led to reduction in the number of tumors. Finally, human NMSC biopsies showed increased LGALS7 mRNA and Gal-7 protein expression and displayed transcriptional profiles associated with myeloid programs, accompanied by elevated CXCL1 expression and c-Met activation. Thus, Gal-7 emerges as a critical mediator of skin carcinogenesis and a potential therapeutic target in human NMSC.

PD-L1 expression and CD8 positive lymphocytes in human neoplasms: A tissue microarray study on 11,838 tumor samples

BACKGROUND

Programmed death ligand 1 (PD-L1) is the target of immune checkpoint inhibitor therapies in a growing number of tumor types, but a unanimous picture on PD-L1 expression across cancer types is lacking.

MATERIALS AND METHODS

We analyzed immunohistochemical PD-L1 expression in 11,838 samples from 118 human tumor types and its relationship with tumor infiltrating CD8 positive lymphocytes.

RESULTS

At a cut-off level of 10% positive tumor cells, PD-L1 positivity was seen in 85 of 118 (72%) tumor types, including thymoma (100% positive), Hodgkin's lymphoma (93%), anaplastic thyroid carcinoma (76%), Kaposi sarcoma (71%), sarcomatoid urothelial carcinoma (71%), and squamous cell carcinoma of the penis (67%), cervix (65%), floor of the mouth (61%), the lung (53%), and pharynx (50%). In immune cells, PD-L1 positivity was detectable in 103 (87%) tumor types, including tumors of haematopoetic and lymphoid tissues (75% to 100%), Warthin tumors of the parotid glands (95%) and Merkel cell carcinoma (82%). PD-L1 positivity in tumor cells was significantly correlated with the number of intratumoral CD8 positive lymphocytes across all tumor types as well as in individual tumor types, including serous carcinoma of the ovary, invasive breast carcinoma of no special type, intestinal gastric adenocarcinoma, and liposarcoma (p< 0.0001 each).

CONCLUSIONS

PD-L1 expression in tumor and inflammatory cells is found in a wide range of human tumor types. Higher rates of tumor infiltrating CD8 positive lymphocytes in PD-L1 positive than in PD-L1 negative cancers suggest that the antitumor immune response may trigger tumoral PD-L1 expression.

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.

Combined response of advanced cutaneous squamous cell carcinoma and renal cell carcinoma to immunotherapy: a case report

Immune checkpoint inhibitors have significantly improved the therapeutic scenario of many different advanced malignancies and could be an effective treatment strategy in synchronous or metachronous tumors. The authors describe the clinical case of a patient who experienced a long-lasting response of his metastatic renal cell carcinoma and an optimal response of his locally advanced cutaneous squamous cell carcinoma to immunotherapy. The systemic treatment was chosen based on a literature review of several clinical reports, since there was no prospective study on anti-PD-1 blockade activity in cutaneous squamous cell carcinoma when the patient started the treatment. This clinical case supports the growing evidence for immunotherapy as a valid treatment option across different types of advanced tumors.

Non-melanoma skin cancers: physio-pathology and role of lipid delivery systems in new chemotherapeutic treatments

Non-melanoma carcinoma has high incidence rates and has two most common subtypes: basal cell carcinoma and squamous cell carcinoma. This type of carcinoma is usually not fatal; however, it can destroy sensory organs such as the nose, ears, and lips. The treatment of these injuries using non-invasive methods is thus strongly recommended. Some treatments for non-melanoma carcinoma are already well defined, such as surgery, cryosurgery, curettage and electrode section, and radiotherapy; however, these conventional treatments cause inflammation and scarring. In the non-surgical treatment of non-melanoma carcinoma, the topical administration of chemotherapeutic drugs contributes for an effective treatment with reduced side effects. However, the penetration of anticancer drugs in the deeper layers of the skin is required. Lipid delivery systems (liposomes, solid lipid nanoparticles, nanostructured lipid carriers) have been developed to overcome epidermal barrier of the skin and to allow the drugs to reach tumor cells. These lipid nanoparticles contribute to control the release profile of the loaded chemotherapeutic drugs, maintaining their stability and increasing death of tumor cells. In this review, the characteristics of non-melanoma carcinoma will be discussed, describing the main existing treatments, together with the contribution of lipid delivery systems as an innovative approach to increase the effectiveness of topical therapies for non-melanoma carcinomas.

Expression Patterns of Necroptosis-Related Genes: Predicting Prognosis and Immunotherapeutic Effects in Cutaneous Melanoma

Background

Increasing evidence has shown a strong correlation between necroptosis and antitumor immunity. However, precise expression patterns of necroptosis-related genes in cutaneous melanoma (CM) have not been clearly elucidated nor have their effects on the immune cell infiltration in the tumor microenvironment.

Method

We investigated the expression patterns of necroptosis-related genes of individuals with cutaneous melanoma based on 67 necroptotic genes and methodically associated the expression patterns with the comprehensive characterization of tumor immune microenvironment. Using principal component analysis methods, the NRG score was developed to quantify the expression patterns of necroptotic genes in CM patients.

Result

Three different necroptotic subtypes were determined with marked survival differences, showing distinct characteristics of immune cell infiltration. The high NRG score group with comprehensive immunosuppression was characterized by the worse immunotherapeutic efficacy and the poor prognosis, while the low NRG score group indicated a robust activation of immune function and a better response to immunotherapy, which may be responsible for a better prognosis. Furthermore, the predictive ability of the NRG score on prognosis and immunotherapeutic benefits was further revalidated using the other independent datasets of cutaneous melanoma. The results indicated that patients with low NRG scores exhibited prolonged survival. Surprisingly, all patients with CM with clinical response, including complete response/partial response, belonged to the low NRG score group.

Conclusion

Our present work revealed the close association between expression patterns of necroptosis-associated genes and tumor immune microenvironment. NRG score can serve as a potential predictor to independently assess patients' prognosis with CM and effectively estimate the response to immunological therapy, thus facilitating the identification of appropriate candidates with CM for immunotherapy and the formulation of individualized therapeutic approaches.

A tEMTing target? Clinical and experimental evidence for epithelial-mesenchymal transition in the progression of cutaneous squamous cell carcinoma (a scoping systematic review)

Cutaneous squamous cell carcinoma (cSCC) is a disease with globally rising incidence and poor prognosis for patients with advanced or metastatic disease. Epithelial-mesenchymal transition (EMT) is a driver of metastasis in many carcinomas, and cSCC is no exception. We aimed to provide a systematic overview of the clinical and experimental evidence for EMT in cSCC, with critical appraisal of type and quality of the methodology used. We then used this information as rationale for potential drug targets against advanced and metastatic cSCC. All primary literature encompassing clinical and cell-based or xenograft experimental studies reporting on the role of EMT markers or related signalling pathways in the progression of cSCC were considered. A screen of 3443 search results yielded 86 eligible studies comprising 44 experimental studies, 22 clinical studies, and 20 studies integrating both. From the clinical studies a timeline illustrating the alteration of EMT markers and related signalling was evident based on clinical progression of the disease. The experimental studies reveal connections of EMT with a multitude of factors such as genetic disorders, cancer-associated fibroblasts, and matrix remodelling via matrix metalloproteinases and urokinase plasminogen activator. Additionally, EMT was found to be closely tied to environmental factors as well as to stemness in cSCC via NFκB and β-catenin. We conclude that the canonical EGFR, canonical TGF-βR, PI3K/AKT and NFκB signalling are the four signalling pillars that induce EMT in cSCC and could be valuable therapeutic targets. Despite the complexity, EMT markers and pathways are desirable biomarkers and drug targets for the treatment of advanced or metastatic cSCC.

Comparative efficacy analysis identifies immune checkpoint blockade as a new survival benchmark in advanced cutaneous squamous cell carcinoma

BACKGROUND

Cutaneous squamous cell carcinoma is a common type of skin cancer that may progress to locally advanced or metastatic disease. Both disease stages are managed by a variety of treatment options, including immune checkpoint blockade (ICB), targeted therapy to epidermal growth factor, chemotherapy or treatment combinations. However, the comparative efficacy of such treatments is unclear.

METHODS

We performed a systematic literature search of Medline, Embase and Central to identify eligible studies reporting Kaplan-Meier curves or individual patient data for overall survival (OS) or progression-free survival (PFS). Kaplan-Meier curves were digitised using the "'WebPlotDigitizer" program. Individual patient data was subsequently remodelled and pooled for distinct treatment groups.

RESULTS

Overall, 22 independent studies were included of which n = 927 patients were evaluable for PFS and n = 1054 for OS. ICB showed the highest median PFS (mPFS 9.9 months (95% CI: 8.1-19.9)) and median OS (mOS not reached (95% CI: 31.5 months-not reached)) compared to chemotherapy (mPFS 3.0 months (95% CI: 2.2-4.8), mOS 12.6 months (95% CI: 9.6-15.8)), targeted therapy to epidermal growth factor (mPFS 4.9 months (95% CI: 4.4-5.6), mOS 12.7 months (95% CI: 11.9-14.9)) and combination therapies without ICB (mPFS 9.1 months (95% CI: 8.0-12.1), mOS 18.1 months (95% CI: 16.3-22.8)). The survival benchmark with ICB after 26 months for metastatic squamous cell carcinoma was 70.8% (95% CI: 61.5%-81.5%) versus 37.9% (95% CI: 29.5%-48.8%) for the combination group and 17.1% (95% CI: 9.5%-30.8%) for chemotherapy.

CONCLUSION

ICB is superior to other systemic treatments and sets a novel survival benchmark for advanced cutaneous squamous cell carcinoma.

Aggressive cutaneous squamous cell carcinoma in a hydroxyurea- and ruxolitinib-pretreated patient with polycythaemia vera

Hydroxyurea and ruxolitinib are frequently used to treat myeloproliferative disorders, including polycythaemia vera, and chronic treatment is associated with many cutaneous adverse effects such as the development of aggressive non-melanoma skin cancer (NMSC). We report an 85-year-old man with a history of hydroxyurea- and ruxolitinib-treated polycythaemia vera who was referred for the management of progressively growing tumours on his scalp. Histopathology of the largest scalp lesion revealed a partly desmoplastic cutaneous squamous carcinoma with perineural invasion. Initial imaging revealed metastatic disease in cervical lymph nodes, bones and lungs. The scalp lesions were successfully treated with bleomycin-based electrochemotherapy. Under initial systemic therapy using four cycles of cetuximab, metastatic disease progressed. Following the approval by the health insurance, compassionate use of pembrolizumab monotherapy was initiated. After three cycles of pembrolizumab, however, metastatic disease further progressed and the patient finally died from global respiratory insufficiency. The present case exemplifies the cutaneous adverse effects of long-term hydroxyurea and ruxolitinib therapy, frequently resulting in highly aggressive NMSCs that are usually not responsive to systemic treatments even such as immune checkpoint inhibitors.

Management of immune-related adverse events in anti-PD-1-treated patients with advanced cutaneous squamous cell carcinoma

Immune checkpoint inhibitors (ICI) have shown very promising results in the management of patients with inoperable or metastatic cutaneous squamous cell carcinoma (cSCC). However, ICI can cause a range of immune-related adverse events (irAEs) affecting a multitude of organs including skin, gastrointestinal tract, endocrine system, heart, lung, kidneys and the nervous system. In principle, clinical management irAEs does not change significantly with respect to the kind of cancer treated with ICI. However, advanced cSCC typically occurs in a clinically challenging patient population typically presenting with advanced age and/or significant comorbidities such as immunosuppression due to haematological malignancies and their respective treatment. Moreover, many patients with advanced cSCC are organ transplant patients taking immunosuppressants. As a consequence use of ICI per se and management of ICI-induced irAEs generates more complexity and difficulties in patients with cSCC compared to other entities. Here, we provide a brief review on the management of anti-programmed cell death protein 1-induced irAEs in patients with cSCC focusing on the characteristic clinical challenges present in this population.

Definitive weekly hypofractionated radiotherapy in cutaneous squamous cell carcinoma: response rates and outcomes in elderly patients unfit for surgery

INTRODUCTION

The optimal definitive radiotherapy (RT) scheme in cutaneous squamous cell carcinoma (cSCC) remains controversial, especially in elderly patients.

METHODS

Data of elderly patients with cSCC lesion(s) treated with weekly hypofractionated RT (8 Gy per week per 7-8 weeks) were analyzed.

RESULTS

Eighteen patients (median age 89 years) with 23 cSCC lesions have been identified including nine males (50%) and nine females (50%). The most common tumor localization was the head and neck region (n = 21; 91.3%), and the majority of lesions (n = 15; 65.2%) was stage ≥ III. At diagnosis, pain and bleeding were ascribed in 13 (56.5%) and eight (34.8%) cSCC, respectively. Compliance with weekly hypofractionated RT was excellent. The overall response rate at 12 weeks after treatment was 95.7%. Bleeding and pain relief were achieved in all cases. Severe toxicity was not recorded. The 1-year overall survival was 66.0%. The 1-year progression-free survival was 58.7%.

CONCLUSIONS

Weekly hypofractionated RT provides a safe, efficient, and cost-effective treatment in elderly cSCC patients with minimal side effects.

Clinical determinants of long-term survival in metastatic uveal melanoma

This study aimed to identify prognostic factors in patients with metastatic uveal melanoma (UM) that were associated with long-term survival in a real-world setting. A total of 94 patients with metastatic UM were included from German skin cancer centers and the German national skin cancer registry (ADOReg). Data were analyzed for the response to treatment, progression-free survival, and overall survival (OS). Prognostic factors were explored with univariate Cox regression, log-rank, and χ2-tests. Identified factors were subsequently validated after the population was divided into two cohorts of short-term survival (< 2 years OS, cohort A, n = 50) and long-term survival (> 2 years OS, cohort B, n = 44). A poor ECOG performance status (hazard ratio [HR] 2.0, 95% confidence interval [CI] 1.0–3.9) and elevated serum LDH (HR 2.0, 95% CI 1.0–3.8) were associated with a poor OS, whereas a good response to immune checkpoint blockade (ICB, p < 0.001), radiation therapy (p < 0.001), or liver-directed treatments (p = 0.01) were associated with a prolonged OS. Long-term survivors (cohort B) showed a higher median number of organs affected by metastasis (p < 0.001), while patients with liver metastases only were more common in cohort A (40% vs. 9%; p = 0.002). A partial response to ICB was observed in 16% (12/73), being 21% (8/38) for combined ICB, 17% (1/6) for single CTLA4 inhibition, and 10% (3/29) for single PD1 inhibition. One complete response occurred in cohort B with combined ICB. We conclude that the response to ICB and the presence of extrahepatic disease were favorable prognostic factors for long-term survival.

Overcoming Resistance to Immunotherapy in Advanced Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma (CSCC) is the second most frequent cancer in humans, and is now responsible for as many deaths as melanoma. Immunotherapy has changed the therapeutic landscape of advanced CSCC after the FDA approval of anti-PD1 molecules for the treatment of locally advanced and metastatic CSCC. However, roughly 50% of patients will not respond to this systemic treatment and even those who do respond can develop resistance over time. The etiologies of primary and secondary resistance to immunotherapy involve changes in the neoplastic cells and the tumor microenvironment. Indirect modulation of immune system activation with new therapies, such as vaccines, oncolytic viruses, and new immunotherapeutic agents, and direct modulation of tumor immunogenicity using other systemic treatments or radiotherapy are now under evaluation in combined regimens. The identification of predictors of response is an important area of research. In this review, we focus on the features associated with the response to immunotherapy, and the evaluation of combination treatments and new molecules, a more thorough knowledge of which is likely to improve the survival of patients with advanced CSCC.

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.

Local Chemotherapy as an Adjuvant Treatment in Unresectable Squamous Cell Carcinoma: What Do We Know So Far?

Background: Squamous cell carcinoma (SCC) is one of the most common cancers involving skin and oral mucosa. Although this condition's gold-standard treatment is the surgical removal of the lesions, the physician must propose alternative treatments in some cases due to the patient's ineligibility for surgery. Among the available alternative therapies, local chemotherapy may represent an initial treatment in combination with radiotherapy or systemic chemotherapy due to the low frequency of side-effects and the lack of necessity for expensive devices. Methods: In this paper, we review all available literature in various databases (PubMed, Scopus-Embase, Web of Science), proposing local chemotherapy as a treatment for cutaneous and oral SCC. Exclusion criteria included ocular lesions (where topical treatments are common), non-English language, and non-human studies. Results: We included 14 studies in this review. The majority were case reports and case series describing the treatment of non-resectable localized SCC with either imiquimod or 5-fluorouracil. We also analyzed small studies proposing combination treatments. Almost all studies reported an excellent clinical outcome, with a low risk of relapses in time. Conclusions: Resection of the lesion remains the gold-standard treatment for SCC. When this approach is not feasible, local chemotherapy may represent a treatment alternative, and it may also be associated with radiotherapy or systemic chemotherapy.

Cutaneous squamous cell carcinoma of head and neck region: A single center analysis of 1296 tumors with clinical characteristics, comorbidities, treatment, and sun-protection behavior

Cutaneous squamous cell carcinoma (SCC) is the second most common non-melanoma skin cancer among Caucasians. We analyzed our data on tumors been treated between 2006 and 2016 at the Skin Cancer Center of an academic teaching hospital. Thousand hundred and ninety-four patients with 1296 SCC have been identified including 804 males (67.3%) and 390 females (32.7%). The mean age among females was significantly higher with (83.9 ± 7.9) years compared with males ([79.3 ± 8.1] years; P < .001). The most common tumor localizations were outer ears (n = 227, 17.5%), scalp (216, 16.7%), and forehead (215, 16.6%). The majority of tumors was stage I. 31.9% of patients had previous SCC or Bowen's cancer, 29.1% had actinic keratoses. Major non-dermatological comorbidities were cardiovascular diseases and diabetes. SCC were treated by delayed Mohs surgery. First Mohs procedure resulted in R0 status in 83.9%. Most cases with R1 resection were located on nose and eyelids. For a subpopulation of patients (n = 105), a structured questionnaire study evaluated changes in sun protection behavior after skin cancer. After the confirmed diagnosis of a cutaneous SCC concerns about harm to the skin by intense sunlight was reported by 78.4% (76) of participants, with 92.0% among females versus 73.6% among males. Eighty percent of females and 76.8% of males wanted to care more about sun-protection in the future, spend less time 84.0% (females) and 72.5% (males) in the sun, and adapt their leisure activities for a better sun protection in 92.0% (females) and 81.9% (males). Secondary prevention in males needs improvement.

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.