SLNB in cutaneous SCC: A review of the current state of literature and the direction for the future

Functionally distinct cancer-associated fibroblast subpopulations establish a tumor promoting environment in squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) is a serious public health problem due to its high incidence and metastatic potential. It may progress from actinic keratosis (AK), a precancerous lesion, or the in situ carcinoma, Bowen's disease (BD). During this progression, malignant keratinocytes activate dermal fibroblasts into tumor promoting cancer-associated fibroblasts (CAFs), whose origin and emergence remain largely unknown. Here, we generate and analyze >115,000 single-cell transcriptomes from healthy skin, BD and cSCC of male donors. Our results reveal immunoregulatory and matrix-remodeling CAF subtypes that may derive from pro-inflammatory and mesenchymal fibroblasts, respectively. These CAF subtypes are largely absent in AK and interact with different cell types to establish a pro-tumorigenic microenvironment. These findings are cSCC-specific and could not be recapitulated in basal cell carcinomas. Our study provides important insights into the potential origin and functionalities of dermal CAFs that will be highly beneficial for the specific targeting of the cSCC microenvironment.

Clinical outcomes of high-risk cutaneous squamous cell carcinomas treated with Mohs surgery alone: An analysis of local recurrence, regional nodal metastases, progression-free survival, and disease-specific death

BACKGROUND

The incidence of cutaneous squamous cell carcinoma (cSCC) continues to increase, and it is now predicted that the number of deaths from cSCC will surpass that of melanoma within the next 5 years. Although most cSCCs are successfully treated, there exists an important subset of high-risk tumors that have the highest propensity for local recurrence (LR), nodal metastasis (NM), and disease-specific death (DSD).

OBJECTIVE

We investigated the clinical outcomes of high-risk cSCCs treated with Mohs surgery (MS) alone, analyzing LR, NM, distant metastasis, and DSD. In addition, we analyzed progression-free survival and DSD in patients who underwent salvage head/neck dissection for regional NMs.

METHODS

Retrospective review of all high-risk cSCC treated in our clinics between January 1, 2000, and January 1, 2020, with follow-up through April 1, 2020.

SETTING

Two university-affiliated, private-practice MS referral centers.

RESULTS

In total, 581 high-risk primary cSCCs were identified in 527 patients, of which follow-up data were obtained for 579 tumors. The 5-year disease-specific survival was 95.7%, with a mean survival time of 18.6 years. The 5-year LR-free survival was 96.9%, the regional NM-free survival was 93.8%, and the distant metastasis-free survival was 97.3%. The 5- and 10-year progression-free survival rates from metastatic disease were 92.6 and 90.0%, respectively. In patients who experienced regional NMs and underwent salvage head and neck dissection with or without radiation, the 2-year disease-specific survival was 90.5%.

CONCLUSION

Our cohort, which is the largest high-risk cSCC cohort treated with MS to date, experienced lower rates of LR, NM, and DSD than those reported with historical reference controls using both the Brigham and Women's Hospital and American Joint Committee on Cancer, Eighth Edition, staging systems. We demonstrated that MS confers a disease-specific survival advantage over historical wide local excision for high-risk tumors. Moreover, by improving local tumor control, MS appears to reduce the frequency of regional metastatic disease and may confer a survival advantage even for patients who develop regional metastases.

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

INTRODUCTION

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.

PATIENTS AND METHODS

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 ≥10 mm and/or thickness ≥4 mm 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).

RESULTS

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.

CONCLUSIONS

SLNB appears to carry no prognostic value for identifying recurrent disease amongst high-risk cSCC in the head and neck area.

Partial EMT in Squamous Cell Carcinoma: A Snapshot

In the process of cancer EMT, some subgroups of cancer cells simultaneously exhibit both mesenchymal and epithelial characteristics, a phenomenon termed partial EMT (pEMT). pEMT is a plastic state in which cells coexpress epithelial and mesenchymal markers. In squamous cell carcinoma (SCC), pEMT is regulated, and the phenotype is maintained via the HIPPO pathway, NOTCH pathway and TGF-β pathways and by microRNAs, lncRNAs and the cancer microenvironment (CME); thus, SCC exhibits aggressive tumorigenic properties and high stemness, which leads collective migration and therapy resistance. Few studies have reported therapeutic interventions to address cells that have undergone pEMT, and this approach may be an effective way to inhibit the plasticity, drug resistance and metastatic potential of SCC.

Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma represents 20% of all skin cancers, resulting in 1 million cases in the United States each year. The lifetime risk of developing squamous cell carcinoma continues to increase annually and will likely continue to increase because of the aging population. Most cutaneous squamous cell carcinoma are treated locally, with a subset leading to recurrence, metastasis, and death. This review of cutaneous squamous cell carcinoma covers incidence, recurrence rates, mortality rates, risk factors, staging systems, treatment, prevention, and monitoring.

Validation of a 40-gene expression profile test to predict metastatic risk in localized high-risk cutaneous squamous cell carcinoma

BACKGROUND

Current staging systems for cutaneous squamous cell carcinoma (cSCC) have limited positive predictive value for identifying patients who will experience metastasis.

OBJECTIVE

To develop and validate a gene expression profile (GEP) test for predicting risk for metastasis in localized, high-risk cSCC with the goal of improving risk-directed patient management.

METHODS

Archival formalin-fixed paraffin-embedded primary cSCC tissue and clinicopathologic data (n = 586) were collected from 23 independent centers in a prospectively designed study. A GEP signature was developed using a discovery cohort (n = 202) and validated in a separate, nonoverlapping, independent cohort (n = 324).

RESULTS

A prognostic 40-GEP test was developed and validated, stratifying patients with high-risk cSCC into classes based on metastasis risk: class 1 (low risk), class 2A (high risk), and class 2B (highest risk). For the validation cohort, 3-year metastasis-free survival rates were 91.4%, 80.6%, and 44.0%, respectively. A positive predictive value of 60% was achieved for the highest-risk group (class 2B), an improvement over staging systems, and negative predictive value, sensitivity, and specificity were comparable to staging systems.

LIMITATIONS

Potential understaging of cases could affect metastasis rate accuracy.

CONCLUSION

The 40-GEP test is an independent predictor of metastatic risk that can complement current staging systems for patients with high-risk cSCC.

Prognostic Value of Tumor Staging: Predicting Nodal Metastases in Cutaneous Squamous Cell Carcinoma

OBJECTIVES

Determine the ability of three staging systems to stratify the risk of nodal metastases in cases of cutaneous squamous cell carcinoma (cSCC). Examine differential staging of tumors across the three systems and the resulting implications for clinical decision making.

STUDY DESIGN

Retrospective chart review.

METHODS

This study included 118 patients who underwent excision of primary cSCC of the head and neck as well as elective neck dissection for the same tumor between 2006 and 2017. Tumors were staged using the 2010 7th edition American Joint Committee on Cancer (AJCC 7) staging system, the 2016 8th edition AJCC staging system (AJCC 8), and the Brigham and Women's Hospital (BWH) alternative tumor staging system published in 2013.

RESULTS

There were 28 patients (23.7%) with positive nodal metastases at the time of tumor excision. Almost all tumors staged as tumor (T)2 using AJCC 7 were upstaged to T3 or T4 using the new AJCC 8, and these two groups accounted for the majority of the nodal metastases. Similarly, the BWH-staged T3 group contained the highest number of tumors with nodal metastases. None of the three staging systems significantly stratified tumors in a manner that predicted the presence of nodal metastases.

CONCLUSION

Individuals with cSCC tumors staged T3 or higher in the AJCC 8 and BWH staging systems should undergo neck dissection, whereas those with lower staging should be discussed with the patient on a case-by-case basis.

LEVEL OF EVIDENCE

4.

Updates on the Management of Non-Melanoma Skin Cancer (NMSC)

Non-melanoma skin cancers (NMSCs) are the most common malignancy worldwide, of which 99% are basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs) of skin. NMSCs are generally considered a curable diseases, yet they currently pose an increasing global healthcare problem due to rising incidence. This has led to a shift in emphasis on prevention of NMSCs with development of various skin cancer prevention programs worldwide. This article aims to summarize the most recent changes and advances made in NMSC management with a focus on prevention, screening, diagnosis, and staging.