Introduction
Skin carcinomas are the most common human cancers. Cutaneous squamous cell carcinoma (cSCC) is the second most common type after basal cell carcinoma, and its dissemination capacity causes significant morbidity, resulting in the majority of non-melanoma skin cancer (NMSC) deaths (Que et al.
2018). Solar ultraviolet radiation is the leading cause of cSCC (Boukamp
2005), and immunosuppression is the second major risk factor (Alam and Ratner
2001). cSCC incidence is increasing among white-skinned populations worldwide (Lomas et al.
2012). A study conducted by the Mayo Clinic showed a 263% overall increase in cSCC incidence from 1976–1984 to 2000–2010 (Muzic et al.
2017). Predictions suggest that cSCC incidence is likely to continue to increase (Goon et al.
2017). Despite its frequency, cSCC is usually excluded from general cancer studies and registries. In France, there are two departmental skin carcinoma registries: the Doubs (
2017) and Haut-Rhin (Buemi et al.
2017) registers. Both show increased cSCC incidence, standardized on the world population, with a male predominance. Increases in cSCC incidence and mortality represent a significant financial burden; therefore, the diagnostic and therapeutic management of cSCC are a major public health issue (Vallejo-Torres et al.
2014).
Although surgery is curative in more than 90% of cases (Brougham et al.
2012), delayed or inadequate management especially in immunocompromised patients may lead to advanced stages (acSCC), locally advanced cSCC or metastatic cSCC, which require radiotherapy and/or systemic therapies (Stratigos et al.
2020). Prior to the immunotherapy era, chemotherapy and epidermal growth factor receptor (EGFR)-targeted therapies were mainly used (Maubec
2020). Since 2018, anti-programmed cell-death protein-1 (PD-1) monoclonal antibodies have emerged for the management of solid tumors, including acSCC. Cemiplimab was the first immunotherapy approved by the Food and Drug Administration (FDA) and the European Medicines Agency (EMA), followed by pembrolizumab (Zelin et al.
2021). In France, cemiplimab was used in an early access program from August 2018 to January 2021.
Due to the lack of epidemiological and demographic data and the public health impact of acSCC, we studied patients starting systemic therapy for acSCC in our referral center during a 5-year period to assess patient characteristics, acSCC details, initial management, systemic therapies, and outcomes.
Discussion
Over the 5-year period, the majority of the patients with acSCC were very frail, elderly, predominantly males, with comorbidities, and more than 25% were immunocompromised. We observed an increase in patient numbers over time, with a mean increase of nearly 20% per year. Patients and their cSCC characteristics were similar over the 5-year period, except that the proportion with a head and neck location tended to increase with time.
Our study showed a clear improvement in OS between the first and second periods, with a twofold improvement in survival. Furthermore, mortality was clearly reduced in patients who received anti-PD-1 therapy compared to those who did not. Immunotherapy has revolutionized the management of some cancers, including acSCC, and cemiplimab was approved after nonrandomized trials (Migden et al.
2018). The pivotal phase II study included 59 patients; the overall response rate (ORR) was 47% [95% CI (34–61)] and the rate of durable disease control (DDC) was 61%. Based on these results, cemiplimab was approved by the FDA in September 2018 and by the EMA in July 2019 for acSCC ineligible for surgery or radiotherapy. In France, there was an early access program to cemiplimab from August 2018 to January 2021 to treat advanced or metastatic cSCC as second-line treatment or as first-line if ineligible for platinum-based chemotherapy. Pembrolizumab was also approved after nonrandomized trials (Maubec et al.
2020; Grob et al.
2020). However, in real-life studies, cemiplimab efficacy results were similar to the results of the phase II trials (Hober et al.
2021; Samaran et al.
2023). A French and Italian multicenter cohort study including respectively 240 (mean age 77 years) and 131 (median age of 79 year) patients showed an ORR of 50.4% and 42.7% (Baggi et al.
2021; Hober et al.
2021). In both studies, head and neck location were significantly associated with a better response. Severe treatment-related AE occurred in arrow 9% of both studies, including a total of 3 deaths. European guidelines and an overview proposed more recently, recommend cemiplimab as first-line treatment in patients with acSCC who are not candidates for curative surgery or radiation (Stratigos et al.
2020; Rubatto et al.
2023). It is important to remember that patients and their care remain complex and heterogeneous, and that it is necessary to define standardized care for this fragile, high-needs patient population (Mannino et al.
2023).
These highly promising results in the management of acSCC are associated with the emergence of immune-related AE that can affect many organs. In most cases, these immune-related AE can be managed (Gambichler et al.
2022). In our cohort, one patient dead immunotherapy-related death (myositis). Our acSCC patients are fragile, and it is important to assess the benefit-risk balance of immunotherapy, which can have severe, sometimes irreversible side effects. In our study, immunosuppression, which was present in 27.6% of patients, was the second most prominent factor modifying OS, with a 1.77-fold increase in the risk of death (HR [95% CI] = 1.77 [1.00; 3.13],
p = 0.05). These patients mainly had hematological neoplasms (51.4%) or organ transplantation (22.8%), usually kidney transplantation. We observed that 37% of the patients with hematological diseases responded to immunotherapy despite immunosuppression, confirming that anti-PD-1 is a good therapeutic option in these patients. Conversely, anti-PD-1 antibodies were not used in transplant patients in this study, because the risk of acute or chronic rejection may lead to death (Tsung et al.
2021). The use of immunotherapy in transplanted patients begin to be reported. A systematic review of the literature, showed that the ORR was 34.5% for all types of cancer, and was significantly better in acSCC with an ORR of 68.2% (15/22). Transplant rejection occurred in 41.2% of cases, graft failure in 23.5% and immune-related AE in 18.5% (Portuguese et al.
2022). These data suggested that adapting anti-rejection therapies and prophylactic corticosteroid may reduce the risk of rejection (Rubatto et al.
2021; Tsung et al.
2021). Short-term efficacy looks promising, but prospective studies with more in-depth follow-up and a standardized protocol are needed.
cSCC and acSCC are major public health concerns due to the large number of patients and social and psychological consequences of acSCC, which include visible skin tumors on the head and neck. Actions that may reduce invasive SCC development (reduced sun exposure, early diagnosis) and better initial management of cSCC cases may decrease the incidence of acSCC. In our cohort, only 55.1% of patient records were discussed in a multidisciplinary meeting at the initial stage and only 26.8% of the 61 patients who had an indication for radiotherapy had access. Furthermore, a retrospective study of German and Austrian populations over a 1-year period analyzed data from 190 patients with cSCC; the results showed that 76 patients had locally advanced cSCC (40%) and 114 had metastatic cSCC (60%) (Hillen et al.
2018). Once diagnosed, most patients (59%) did not receive any therapy and only 32 patients (16.8%) received systemic antitumor therapies. The knowledge of physicians (surgeons, general practitioners, and dermatologists) who initially treat cSCC in these patients should be improved, and systematic discussion of such cases in multidisciplinary meetings could contribute to halting the increased incidence of acSCC.
The strength of this study lies in its unique nature, as epidemiological data on cSCC and acSCC are very scarce. Indeed, the latest national report with incidence and mortality estimates of cancer in metropolitan France covers the period from 1990 to 2018 (Deffossez et al.
2019), and provides no data on cSCC because it excludes NMSC. Although our study was based on a small patient cohort, the number of patients treated for carcinoma appears to have increased during the 5-year period. Advanced age and immunosuppression were associated with lower PFS. Overall survival was better in the most recent period and was significantly better in patients who received immunotherapy.
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