Study of a Strategy Integrating Adjuvant Radiation Therapy Versus Strategy Based on Monitoring in the Treatment of Carcinomas Spinocellular With High Risk of Recurrence

The goal of this clinical trial is to evaluate a strategy integrating adjuvant radiation therapy versus strategy based on monitoring in the treatment of carcinomas spinocellular with high risk of recurrence (SCC).

The investigators will compare the disease-free survival (DFS) of patients treated with adjuvant radiation therapy versus surveillance in high risk of recurrence SCC.

The main question it aims to answer is:

Is DFS different between the "adjuvant radiotherapy" group and the "surveillance" group?

Participants will:

* be distributed in one of the two arms
* will be followed up every 4 months for 2 years, then every 6 months (clinical examination, identification of concomitant treatments, imaging, quality-of-life questionnaire)
* followed up until their death or their progression whether local, regional or metastatic

The use of adjuvant radiotherapy appears to provide clinical benefit, both theoretically and based on available retrospective data. This is why some patients already benefit from this complementary treatment. However, given the lack of prospective data, the use of adjuvant radiotherapy is based on heterogeneous criteria, depending on the choice of the clinician in charge of the patient or the habits of his institution.

The sponsor team therefore propose to conduct a national prospective study to compare the efficacy and safety of a strategy integrating adjuvant radiotherapy versus a strategy based on surveillance in patients with SCC at high risk of recurrence.

Considering that there is no validated standard after surgery for patients with a high risk of recurrence, it is not possible to determine a standard arm and an experimental arm. This study therefore falls within the framework of a Research Involving the Human Person of Category 2.

This protocol constitutes the first prospective evaluation of adjuvant radiotherapy, within the framework of a comparative study. This study will thus make it possible to avoid the use of this therapeutic alternative, without rigorous evaluation in a prospective framework. Its robust methodology will make it possible to determine whether adjuvant radiotherapy provides a clinical benefit to patients at high risk of recurrence. It will modify the standards of care for this patient population.

Eligibility Criteria:
Inclusion Criteria:

* Patients ≥ 18 years of age at the time of signing informed consent to participate;
* Patient with histologically confirmed, localized skin squamous cell carcinoma; Note bene: patients with carcinoma of the external auditory canal may be included in the study;
* Patient treated with complete excision surgery (R0), regardless of margin (inframillimetric or supramillimetric);
* High risk disease defined by: presence of a microscopic PNI without/with another risk factor (among those mentioned below) OR presence of 2-3 risk factors other than microscopic PNI; Note Bene: The risk factors selected are immunosuppression (only haematopathy with or without treatment) , a tumor diameter \>20mm, specific location (lip/ear/temple), deep invasion (thickness \>6mm or invasion beyond subcutaneous fat), low differentiation or desmoplasia;
* Patient informed and having signed consent to participate in the study;
* Patient affiliated with a health insurance plan (or beneficiary of such a plan).

Exclusion Criteria:

* Patient with in situ or mixed SCC;
* History of SCC at high risk of relapse in the same territory (head and neck, trunk or limb) in the 2 years preceding the date of randomization;
* History of SCC having received systemic treatment;
* Patient with SCC located in the endonasal, intra-oral, anogenital or vulvar mucosa;
* Patient with recurrent SCC or SCC at very high risk of relapse defined by one of the following criteria:

  * PNI with \> 2 other risk factors,
  * \> 3 risk factors,
  * bone invasion,
  * immunosuppression by immunosuppressive treatments (whatever the reason).
* Patient with SCC with a single risk factor other than PNI;
* Patient with SCC with lymph node or distant metastasis;
* Patient with a history of solid cancer undergoing chemotherapy;
* Patient with a contraindication to radiotherapy;
* Patient with a history of radiotherapy in the area of the lesion;
* Participation in another clinical trial that may interfere with the assessment of the primary endpoint;
* Patient under guardianship or curatorship or deprived of liberty;
* Pregnant or breastfeeding woman.