Study protocol of the BASINEL Study: a pragmatic randomised controlled trial investigating treatment versus no treatment of low-risk basal cell carcinomas in older persons.

Introduction: Basal cell carcinomas (BCCs) represent 70% of all skin cancers. These tumours do not metastasise but are locally invasive if left untreated. There is a high incidence of BCC in the elderly, and clinicians frequently face important treatment dilemmas. The approach to BCC in the elderly should be investigated thoroughly.

Methods And Analysis: Data on health-related quality of life (HrQoL), survival and complication rate will be examined in a treatment and a non-treatment arm (1:1 allocation). In the non-treatment arm, in vivo biological behaviour of low-risk BCCs in elderly patients will be examined. The main objective is to combine tumour characteristics with demographic data, in order to determine whether treatment will positively affect the patients' HrQoL within a predetermined time frame. A monocentric randomised controlled trial (RCT) was designed at the Ghent University Hospital. The study population consists of patients with the minimum age of 75 years and a new diagnosis of (a) low-risk BCC(s). Patients in the treatment arm will receive standard care. Patients in the non-treatment arm will be closely monitored: the tumour will be intensively evaluated using multispectral dermoscopy, reflectance confocal microscopy and high-definition optical coherence tomography. All patients will be asked to fill in a questionnaire concerning their HrQoL at consecutive time points. Patient-reported side effects will be evaluated via an additional questionnaire.Primary outcomes will include the difference in HrQoL and the difference in complication risks (treatment vs non-treatment) at different time points of the study. Secondary endpoints are the evolution of the BCCs in the non-treatment arm and the long-term survival in both study arms. Tertiary endpoint is the treatment effectiveness in the treatment arm. The sample size calculation was performed and resulted in a target sample size of 272 patients in this study with a 1:1 allocation.

Ethics And Dissemination: Subjects can withdraw from participating in this study at any time for any reason without any consequences. Approval for this study was received from the Ethics Committee of the Ghent University Hospital on 26 August 2021.The results of this RCT will be submitted for publication in one or more international, peer-reviewed medical journals, regardless of the nature of the study results.

Trial Registration Number: ClinicalTrials.gov (NCT05110924).