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Non melanoma skin cancer is the most frequent malignancy worldwide. Its development is related to age, high exposure to ultraviolet rays, fair skin and immunosuppression. Eighty percent usually occur in areas of the head and neck and are mostly basal cell carcinomas and squamous cell carcinomas.

Surgery is usually the treatment of choice, however, radiotherapy is an effective option in patients who are not candidates for surgical resection due to comorbidities, age, location or post-surgical morbidity.

Our aim has been to evaluate the differences in effectiveness and toxicity between two types of superficial radiotherapy treatments: low energy photons and electronic brachytherapy. 

Patients with non-melanoma skin cancer treated with superficial radiotherapy with radical intent between October 2019 and June 2021 were retrospectively collected. Treatment was administered by low-energy photons using Therapax 150 orthovoltage devices or 50 Kv X-rays using the Axxent Xoft device (electronic surface brachytherapy).  Demographic and anatomopathologic data, as well as treatment characteristics, toxicities (CTCAE V5) and observed results were compared between both groups. Student's T was used for quantitative variables and chi-square for qualitative variables with p<0.05 being considered as statistically significant differences. 

There were 61 treatments 51% performed with Axxent and 49% with Therapax.

No statistically significant differences were found between Axxent and Therapax in terms of sex distribution (men 57% and 52% respectively), mean age (84.3 and 85.3 years), type of histology basal cell (77% and 80%), squamous (13% and 20%) and lymphoma (5% and 0%). No differences were also found in terms of their main locations: nasal (32% and 37%), fronto-parietal (29% and 27%) and malar (13% and 10%).

Differences were found between the total mean dose in both groups (p= 0.00) 41.06 Gy Axxent and 50.67 Gy Therapax as well as the equivalent biological dose 52.06 Gy and 67.03 Gy respectively (p= 0.00).

No differences were found in the degree of toxicity observed between Axxent and Therapax presenting radiodermatitis at the end of treatment G2 in 16% and 20% (P= 0.69) and G3 in 16% and 3% respectively (p=0.09). No correlation was found either between BED or EQD2 with respect to the degree of toxicity.

Regarding the observed clinical pathological response, no differences were found (P=0.83) between treatments with a percentage of complete response of 74% and 83% respectively. 

Both superficial low energy photon radiotherapy and superficial electron brachytherapy are effective and well tolerated treatments in non-melanoma skin cancer with radical intent.