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

Inclusion Criteria:

I1. Patients aged ≥ 18 years at the time of signing the informed consent form; I2. Patients with histologically confirmed localized cutaneous squamous cell carcinoma;

Note: Patients with carcinoma of the external auditory canal may be included in the study;

I3. Patients treated with complete surgical excision (R0), regardless of the margin (submillimeter or supramillimeter);

I4. Disease with a high risk of recurrence defined by one of the following scenarios:

* presence of microscopic EPN without any other risk factors;
* presence of microscopic EPN with a single other risk factor;
* presence of 2 risk factors other than microscopic EPN;
* presence of 3 risk factors other than microscopic EPN;

Note: The risk factors considered are immunosuppression (limited to untreated hematologic disease), a tumor diameter \>20 mm (longest axis, measured preferably clinically, or, failing that, histologically), a specific location (lip/ear/temple), deep invasion (tumor thickness \>6 mm (Breslow) or invasion beyond the subcutaneous fat), poor differentiation, or desmoplasia;

I5. Patient informed and having signed a consent form to participate in the study; I6. Patient enrolled in a health insurance plan (or beneficiary of such a plan).

Exclusion Criteria:

NI1. Patients with in situ or mixed CEC; NI2. History of CEC with a high risk of recurrence in the same lymphatic drainage area (head and neck, trunk, or limb) within 2 years prior to the randomization date; NI3. History of CEC treated with systemic therapy; NI4. Patients with SCC localized to the endonasal, intraoral, anogenital, or vulvar mucosa;

NI5. Patients with recurrent SCC or SCC at very high risk of recurrence defined by one of the following criteria:

* EPN with ≥ 2 other risk factors,
* \> 3 risk factors,
* bone invasion,
* immunosuppression due to immunosuppressive treatments (regardless of the reason). NI6. Patients with CEC presenting a single risk factor other than EPN; NI7. Patient with CEC and lymph node or distant metastasis; NI8. Patient with a history of cancer undergoing systemic and/or locoregional anticancer treatment;

Note: Local treatment of cutaneous keratoses with fluoropyrimidines is permitted outside the theoretical radiation field);

NI9. Patient with a contraindication to radiation therapy; NI10. Patient with a history of radiation therapy to the site of the lesion; NI11. Participation in another clinical trial that may interfere with the assessment of the primary endpoint; NI12. Patient under legal guardianship or conservatorship, or deprived of liberty; NI13. Pregnant or breastfeeding woman.