Implications of Satellitosis or In-transit Metastasis in Cutaneous Squamous Cell Carcinoma: A Prognostic Omission in Cancer Staging Systems

Neoadjuvant-Intent Immunotherapy in Advanced, Resectable Cutaneous Squamous Cell Carcinoma

Importance

In clinical trials, preoperative immune checkpoint inhibitors (ICIs) have shown clinical activity in advanced cutaneous squamous cell carcinoma (cSCC). However, these studies excluded patients with relevant comorbidities.

Objective

To evaluate radiologic and pathologic response rates to neoadjuvant-intent programed cell death protein 1 (PD-1) ICIs in a clinical population.

Design, Setting, and Participants

This cohort study of patients who were treated with neoadjuvant cemiplimab or pembrolizumab for advanced cSCC from January 2018 to January 2023 was conducted at 2 academic institutions in Boston, Massachusetts. Median follow-up was 9.5 months (range, 1.2-40.5).

Exposures

Cemiplimab or pembrolizumab.

Main Outcomes and Measures

Primary outcomes were radiologic and pathologic response rates. Secondary outcomes were 1-year recurrence-free survival, progression-free survival, disease-specific survival, and overall survival.

Results

This cohort study included 27 patients (including 9 patients [33.3%] with a history of lymphoma). Most patients were male (18 of 27 [66.7%]), with a median age of 72 years (range, 53-87 years). Most primary tumors were located on the head/neck (21 of 27 [77.8%]). There were no unexpected delays in surgery. The median number of doses before surgery was 3.5 (range, 1.0-10.0). Five patients (18.5%) ultimately declined to undergo planned surgery due to clinical responses or stability, and 1 (3.7%) did not undergo surgery due to progressive disease. The overall pathologic response rate (pathological complete response [pCR] or major pathological response) was 47.4% (9 of 19), and the overall radiologic response rate (radiologic complete response or partial response) was 50.0% (8 of 16). The pCR rate (7 of 19 [36.8%]) was higher than the radiologic complete response rate (2 of 16 [12.5%]). The pCR rate among patients with cSCC and concomitant lymphoma was 25.0%. The 1-year recurrence-free survival rate was 90.9% (95% CI, 50.8%-98.7%), progression-free survival was 83.3% (95% CI, 27.3%-97.5%), disease-specific survival was 91.7% (95% CI, 53.9%-98.8%), and overall survival was 84.6% (95% CI, 51.2%-95.9%).

Conclusions and Relevance

The results of this cohort study support the reproducibility of neoadjuvant-intent immunotherapy for cSCC in the clinical setting, including for patients with a history of lymphoma. Outside of clinical trials, it is not infrequent for patients to opt out of surgery for regressing tumors. The inclusion of higher-risk patients and preference for nonsurgical treatment are 2 factors that might explain the numerically lower pathologic response rate in this institutional experience.

The role of micrometastasis in high-risk skin cancers

The propensity to metastasize is the most important prognostic indicator for solid cancers. New insights into the mechanisms of early carcinogenesis have revealed micrometastases are generated far earlier than previously thought. Evidence supports a synergistic relationship between vascular and lymphatic seeding which can occur before there is clinical evidence of a primary tumour. Early vascular seeding prepares distal sites for colonisation while regional lymphatics are co-opted to promote facilitative cancer cell mutations. In response, the host mounts a global inflammatory and immunomodulatory response towards these cells supporting the concept that cancer is a systemic disease. Cancer staging systems should be refined to better reflect cancer cell loads in various tissue compartments while clinical perspectives should be broadened to encompass this view when approaching high-risk cancers. Measured adjunctive therapies implemented earlier for low-volume, in-transit cancer offers the prospect of preventing advanced disease and the need for heroic therapeutic interventions. This review seeks to re-appraise how we view the metastatic process for solid cancers. It will explore in-transit metastasis in the context of high-risk skin cancer and how it dictates disease progression. It will also discuss how these implications will influence our current staging systems and its consequences on management.

Management of Cutaneous Squamous Cell Carcinoma of the Scalp: The Role of Imaging and Therapeutic Approaches

Cutaneous squamous cell carcinoma (cSCC) is the second most common subtype of skin cancer. The scalp is one of the most frequently affected locations and is associated with a higher rate of complications, compared to other locations. In addition, it has a characteristic thickness and anatomical structure that may influence both growth pattern and treatment of primary cSCC; while clinical peripheral margins may be easily achieved during the surgery, vertical excision of the tumor is limited by the skull. Despite having a unique anatomy, current guidelines do not contemplate specific recommendations for scalp cSCC, which leads to inconsistent decision-making in multidisciplinary committees when discussing tumors with high risk factors or with close margins. This article provides specific recommendations for the management of patients with scalp cSCC, based on current evidence, as well as those aspects in which evidence is lacking, pointing out possible future lines of research. Topics addressed include epidemiology, clinical presentation and diagnosis, imaging techniques, surgical and radiation treatments, systemic therapy for advanced cases, and follow-up. The primary focus of this review is on management of primary cSCC of the scalp with localized disease, although where relevant, some points about recurrent cSCCs or advanced disease cases are also discussed.

European consensus-based interdisciplinary guideline for invasive cutaneous squamous cell carcinoma. Part 1: Diagnostics and prevention-Update 2023

Invasive cutaneous squamous cell carcinoma (cSCC) is one of the most common cancers in white populations, accounting for 20% of all cutaneous malignancies. Overall, cSCC mostly has very good prognosis after treatment, with 5-year cure rates greater than 90%. Despite the overall favourable prognosis and the proportionally rare deaths, cSCC is associated with a high total number of deaths due to its high incidence. A collaboration of multidisciplinary experts from the European Association of Dermato-Oncology (EADO), the European Dermatology Forum (EDF), the European Society for Radiotherapy and Oncology (ESTRO), the European Union of Medical Specialists (UEMS), the European Academy of Dermatology and Venereology (EADV) and the European Organization of Research and Treatment of Cancer (EORTC), was formed to update recommendations on cSCC, based on current literature and expert consensus. Part 1 of the guidelines addresses the updates on classification, epidemiology, diagnosis, risk stratification, staging and prevention in immunocompetent as well as immunosuppressed patients.

Implementing structured pathology reporting protocol for non-melanocytic skin cancers: practical considerations

Non-melanocytic skin cancers (NMSCs) account for five times the incidence of all other cancers combined and cost US $6 billion annually. These are the most frequent specimens encountered in community pathology practice in many Western countries. Lack of standardised structured pathology reporting protocols (SPRPs) can result in omission of critical information or miscommunication leading to suboptimal patient management. The lack of standardised data has significant downstream public health implications, including insufficient data for reliable development of prognostic tools and health-economy planning. The Royal College of Pathologists of Australasia has developed an NMSC SPRP. A multidisciplinary expert committee including pathologists, surgeons, dermatologists, and radiation and medical oncologists from high volume cancer centres was convened. A systematic literature review was performed to identify evidence for including elements as mandatory standards or best practice guidelines. The SPRP and accompanying commentary of evidence, definitions and criteria was peer reviewed by external stakeholders. Finally, the protocol was revised following feedback and trialled in multiple centres prior to implementation. Some parameters utilised clinically for determining management and prognosis including tumour depth, lymphovascular invasion or distance to the margins lack high level evidence in NMSC. Dermatologists, surgeons, and radiation oncologists welcomed the SPRP. Pathologists indicated that the variety of NMSC specimens ranging from curettes to radical resections as well as significant differences in the biological behaviour of different tumours covered by the NMSC umbrella made use of a single protocol difficult. The feedback included that using a SPRP for low risk NMSC was neither clinically justified nor compensated adequately by the Australian Medicare Reimbursement Schedule. Following stakeholder feedback, the SPRP implementation was restricted to excision specimens of head and neck NMSC; and low-risk NMSC, such as superficial basal cell carcinoma, were excluded. Implementing NMSC SPRP fulfils an unmet clinical need. Unlike other cancers, NMSCs generate a range of specimen types and are reported in a wide range of pathology practices. Limiting use of SPRP to NMSC at higher risk of progression and providing formatted templates for easy incorporation into laboratory information systems were essential to successful deployment. In the future, further consideration should be given to implementing the SPRP to include all relevant specimens, including non-head and neck and low-risk NMSC specimens.

Prognostic factors for satellitosis or in-transit metastasis in cutaneous squamous cell carcinoma: A multicentric cohort study

BACKGROUND

Satellitosis or in-transit metastasis (S-ITM) has clinical outcomes comparable to node-positivity in cutaneous squamous cell carcinoma (cSCC). There is a need to stratify the risk groups.

OBJECTIVE

To determine which prognostic factors of S-ITM confer an increased risk of relapse and cSCC-specific-death.

METHODS

A retrospective, multicenter cohort study. Patients with cSCC developing S-ITM were included. Multivariate competing risk analysis evaluated which factors were associated with relapse and specific death.

RESULTS

Of a total of 111 patients with cSCC and S-ITM, 86 patients were included for analysis. An S-ITM size of ≥20 mm, >5 S-ITM lesions, and a primary tumor deep invasion was associated with an increased cumulative incidence of relapse (subhazard ratio [SHR]: 2.89 [95% CI, 1.44-5.83; P = .003], 2.32 [95% CI, 1.13-4.77; P = .021], and 2.863 [95% CI, 1.25-6.55; P = .013]), respectively. Several >5 S-ITM lesions were also associated with an increased probability of specific death (SHR: 3.48 [95% CI, 1.18-10.2; P = .023]).

LIMITATIONS

Retrospective study and heterogeneity of treatments.

CONCLUSION

The size and the number of S-ITM lesions confer an increased risk of relapse and the number of S-ITM an increased risk of specific-death in patients with cSCC presenting with S-ITM. These results provide new prognostic information and can be considered in the staging guidelines.