Eyelid sebaceous gland carcinoma: a protocol for a systematic review and meta-analysis of clinicopathological studies of prevalence

Introduction Sebaceous gland carcinoma (SGC) of the eyelid is an aggressive tumour with the ability to metastasise and an increased morbidity. Controversies regarding the epidemiology of this malignant eyelid tumour is widespread in the scientific literature. Western reports repeatedly describes eyelid SGC as a rare occurring tumour in general, accounting for 1%–3% of all eyelid tumours, however studies from Asia have uncovered a higher frequency of eyelid SGC including 54% of all eyelid tumours in Japan, and 43%–56% in India. We wish to retrieve observational data of eyelid SGC prevalence in proportion to total eyelid tumours, from pathological studies published worldwide to resolve this controversy. Methods and analysis We will search Ovid Medline, EMBASE, Cochrane Central Register of Controlled Trials, Scopus and Google Scholar to identify published reports on eyelid SGC prevalence proportions, aiming to clarify the incidence of the tumour. We will include observational clinicopathological studies reporting prevalence with confirmed histopathology. No limitations on publication date or language will be applied. Data from the individual studies and study quality will be extracted by two individual reviewers. Study quality will be assessed using the JBI Critical Appraisal Instrument for Studies Reporting Prevalence Data. Raw proportions will be transformed and pooled using a random effects model for meta-analysis. And subgroup analysis according to geography will be performed. If data are deemed unsuitable for a meta-analysis, a narrative synthesis will be presented. We will judge the certainty of evidence and present whether this has an overall effect on the results. The results may shed light on a long-standing academic disparity of the scientific literature. Ethics and dissemination This systematic review does not require ethical approval. The results of this proposed review will be the subject to a publication in an international peer-reviewed journal within the ophthalmic or pathological specialty. PROSPERO registration number CRD42023487141.