EGFR is expressed in a minority of tumours and then is not always activated. These results show that, before designing a trial with a targeted agent such as an EGFRI in SCC of the skin, it is important to verify the presence of the appropriate target to maximize the best outcome.

High-risk skin cancer arising on the upper limb or trunk can cause axillary nodal metastases. Previous studies have shown that axillary radiotherapy improves regional control. There is little published work on technique. Technique standardization is important in quality assurance and comparison of results especially for trials. Our technique, planned with CT assistance, is presented. To assess efficacy, an audit of patients treated in our institution over a 15-month period was conducted. Of 24 patients treated, 13 were treated with radical intent, 11 with this technique. With a follow up of over 2 years, the technique had more than a 90% (10/11) regional control in this radical group. Both of the radical patients who were not treated according to the technique had regional failure. One case of late toxicity was found, of asymptomatic lymphoedema in a radically treated patient. This technique for axillary radiotherapy for regional control of skin cancer is acceptable in terms of disease control and toxicity as validated by audit at 2 years.

We describe three cases of keratoacanthomas (KAs) following definitive volumetric modulated arc therapy (VMAT) for skin field cancerisation (SFC). One lesion arose on a back in an area that had received a total of 30.6 Gy in 17 fractions. It first became apparent at 24 days post RT and resolved without treatment by 150 days. The other arose on a nasal alar in the beam penumbra that received 36Gy in 25 fractions, appearing at 57 days and resolving without treatment by 85 days. A third case occurred in an immunosuppressed patient. She developed KAs in one of two areas irradiated with lesions appearing at 21 days post RT and finally resolving at 300 days despite acitretin. The area received a total dose of 41.4 Gy in 23 fractions. Spontaneous resolution of index KA confirmed the diagnosis in all cases. On average, the patients were 79 years of age, the area bearing the KA had received an average of 36Gy in 22 fractions. The average onset of the KAs was 24 days or 3.5 weeks or one month after RT, and always soon after reepithelization was completed. Resolution was at an average of 168 days or 24 weeks or 6 months after the completion of RT. In all three cases other lesions arose adjacent to them and, in each case, one of these other lesions was excised with histopathology confirming squamo-proliferative lesions. There has been no recurrence at least 6 months after the last follow up. To our knowledge these are the first three cases of KA described following definitive VMAT for SFC. The possibility of KA arising after RT does need to be considered during the consent process.

Introduction: Atypical intraepidermal melanocytic proliferation (AIMP) is an early form of lentigo maligna (LM) which itself is a precursor to melanoma. It presents commonly on the head and neck where tissue conserving therapies are attractive. When treating LM with imiquimod, dermatologists treat until a certain level of skin inflammation is achieved. Radiation oncologists treat to a set dose of radiation irrespective of the skin reaction at completion. The dose of radiotherapy for AIMP is unknown and these lesions are currently treated in the same manner as LM. Case series: Five immunocompetent patients (average age 80 years) with AIMP or early LM (ELM) on the head and neck region were treated with RADICAL radiotherapy (RT) protocols. All treatment sites were mapped with in vivo reflectance confocal microscopy (RCM) and measured on average 4.0 cm in diameter (range 2.0–6.0 cm). The median RT dose administered was 50 Gray (Gy) [45-54 Gy] in 1.8-2Gy per fraction to the planning target volume (PTV), usually by megavoltage electrons. All patients completed RT. The peak radiation acute skin toxicity observed at any time in all patients was only dry desquamation, equivalent to a grade 2 acute radiation dermatitis reaction by Common Terminology Criteria for Adverse Events (CTCAE) Version 5.0. At a median of follow up of 10 months, all patients had biopsy proven recurrence of AIMP (n=3) or LM (n=2). All recurrences were within the RT field. Patients were followed for an average total of five years post salvage treatment (range: 26 - 124 months). Discussion: This series raises questions. First, what radiation dose is required to cure AIMP and ELM? This series suggests that the same dose, if not higher, used in established in-situ disease, is required. Second, should radiation oncologists treat to a grade 3 skin reaction? It may be then advisable to use standard fractionation (2Gy or less) so that the peak RT reaction coincides with the end of treatment and allows for titration and extra dose to be added.

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