Cases selection

In order to circumvent ambiguity in the definition of the word ‘locally advanced’, we addressed these tumors with a more practical definition, i.e. ‘difficult‐to‐treat’ BCCs (DTT‐BCCs), as defined by the practitioners themselves.

Patient cases considered ‘difficult to treat’ for any reason by the dermatologist trained in cancers of EADO were collected from 11 centers of the EADO group. Each case was recorded on a dedicated website on a standardized one‐sheet document anonymized and blinded with 1–5 pictures of the lesion (and radiography, if relevant) and a standardized case report (Fig. 2). The latter included demography, ECOG status, number of other BCC, past treatments with dates, histopathological subtype, major treatments which can interfere with surgery, other comorbidities, and finally the reasons for which this BCC had been considered ‘difficult‐to‐treat’ by the treating physician. An independent expert (KP) was responsible for the selection of cases, completing recruitment when all the variability of DTT‐BCC in the practice was considered represented in this collection of cases.

Example of a standardized case report sheet submitted to the experts.