Evolution in the management of skin malignant lesions using new radiotherapy techniques

Introduction Radiotherapy plays an important role in the treatment of skin tumours. For skin carcinomas, external irradiation (kilovoltage X-rays or electrons according to clinical characteristics) is more preferable than interstitial brachytherapy, which is recommended for tumours of the lip and nasal vestibule. Electrons are usually used for treating superficial lesions and skin cancers, as well as in the orthovoltage radiotherapy. In order to treat mycosis fungoides, total cutaneous electron beam radiation therapy is efficient for patients with limited superficial plaques. In the treatment of classical form of Kaposi’s sarcoma, radiotherapy can achieve local control, whereas it gives good palliative results in the epidemic form. New radiotherapy techniques, such as helical tomotherapy, showed increased advantages, including dose escalation to the target tumour volume and the best protection of adjacent organs at risk. The aim of this work is to accurately evaluate the efficiency and tolerance of old and new radiotherapy techniques in the treatment of different skin tumours and to review the already existing techniques. Conclusion With all these new treatment modalities, the modern radiotherapy technique becomes a highly adapted treatment for different tumour types, which is a part of the multidisciplinary management. Introduction Radiotherapy plays an important role in the treatment of skin tumours, such as those arising from non-melanoma skin cancer and primary cutaneous lymphoma. For non-melanoma skin cancers, including basal cell carcinoma (BCC), cutaneous squamous cell carcinoma (CSC), Merkel cell carcinoma (MCC) and adnexal carcinoma (AC), complete surgical excision with a security margin is still the reference therapy. But, the choice of the treatment technique depends on various factors, such as the size of the tumour, the general condition of the patient, cosmetic considerations and recurrence. Radiotherapy is an effective option to control tumour growth and to improve quality of life of the patient. Histological confirmation is essential before radiotherapy initiation. For BCCs, radiotherapy is an alternative option if surgery is not preferred due to recurrence, incomplete excision, nodules of >2 cm in the head, or bone or cartilage involvement1. In such cases, 5–10-mm security margins are maintained depending on the tumour size, and superficial Xrays and electron beams are usually employed. A randomised controlled trial was conducted to compare radiotherapy with surgical excision of facial BCC of <4-cm diameter with 4-year failure rates of 7.5% and 0.7%, respectively (P = 0.003). Cosmetic outcomes significantly favoured surgical excision at 4 years in 87% of the surgery-treated patients, whereas 69% of the radiation-treated patients opined the cosmetic results to be satisfactory (P < 0.01). The study used different techniques of radiotherapy, including interstitial brachytherapy, contact therapy and conventional radiotherapy2. Despite these results, radiotherapy is still an option for BCCs that occur in areas where surgery would be technically difficult or would result in unacceptable tissue destruction, or for patients who would not be able to tolerate surgery3. In a study, the efficacy of electron beam radiotherapy for BCCs was evaluated; and 3-year local recurrence-free survival rates were found to be 97.6% for tumours treated with 54 Gy in 18 fractions and 96.9% with 44 Gy in 10 fractions4. Radiotherapy has also been compared with treatment with imiquimod 5% cream for nodular BCCs on the eyelid; in this study, remission rates were equivalent in both the groups, but tolerability was better in the radiotherapy group during the treatment5. For CSCs, radiotherapy is recommended when surgery is not possible, or it is used as an adjuvant in the treatment of high-risk tumours with 10–15-mm security margins6. The 3-year freedom from local recurrence was 97% with 54 Gy in 18 fractions, whereas it was 93.6% with 44 Gy in 10 fractions in a study about electron beam therapy4. Radiotherapy is particularly an option for CSCs overlying cartilage7, those with perineural invasion8,9, or with recurrence10. Adjuvant radiotherapy is also indicated of there is regional lymph node involvement11,12. For MCCs, radiotherapy is applied to the cavity of the excised primary or recurrent tumour13. Adjuvant regional radiotherapy on the tumour bed decreases regional recurrence, but * Corresponding author Email: [email protected] 1 Department of Radiation Oncology, Curie Institute, 26 Rue d’Ulm, 75005 Paris, France 2 Department of Dermatology, Cochin Hospital, 27 Rue du Faubourg Saint-Jacques, 75014 Paris, France