Comments on: "Clinical implementation of a new electronic brachytherapy system for skin brachytherapy".

We have read with an interest the article of Olga Pons-Llanas et al. [1] published in the Journal about the use of electronic brachytherapy (EBT) in non-melanoma skin cancer (NMSC). However, we noticed the exclusion criteria for the following tumors: lesions with a diameter greater than 20 mm, invasion of more than 4 mm, irregular anatomic areas. Besides, there are limits linked to the use of circular collimators and the daily set-up position. NMSC often have irregular shapes and diameter longer than 2 cm; besides, in most cases, NMSC are recurrent and located in periorbital area (i.e. inner canthus). In these instances, both EBT and brachytherapy are difficult and/or inadequate to treat safely most of patients. Among the new technologies, stereotactic ablative radiation therapy could be a valid therapeutic option treating “difficult NMSC”. In a recent paper [2], we reported our experience with Stereotactic Body Radiation Therapy (SBRT) in a patient with recurrent and complicated NMSC using Cyberknife System (CKS). In fact, the CKS is a possible alternative to surgery and brachytherapy in patients with recurrent NMSC located in irregular anatomical areas close to critical organs (i.e. eyes). The SBRT with image guided exceeds the limits of the set-up for relocation; the inverse planning allows to cover irregular volumes greater than 20 mm. The use of the photons X-6 MV permits to treat the lesions with invasion more than 4 mm. Do Olga Pons-Llanas et al. have experience and/or data on the use of brachytherapy in “difficult areas”? In fact, in daily clinical practice many patients have “irregular and difficult” NMSC and it is important that Radiation Oncologists have more therapeutic options in these instances. We think that it is important for the authors to comment on these issues and perhaps reply within the context of this journal.