Topical Therapy for non-invasive penile cancer (Tis)—updated results and toxicity

Penile cancer is a rare malignancy estimated to affect 26,000 men globally each year. The association with penile cancer, in particular non-invasive disease, and human papilloma virus (HPV) is well known. Ninety-five percent of cases of penile cancer are squamous cell carcinoma (SCC), which are staged using the TNM staging system. Terminology describing the histological appearance of non-invasive penile cancer has changed with all cases grouped under the umbrella term of penile intraepithelial neoplasia (PeIN); either undifferentiated or differentiated. This replaces previous terms such as carcinoma in situ (CIS) and eponymous names such as Bowen's disease. This change is recognised by the World Health Organisation (WHO). The topical treatments most commonly used for PeIN are 5-fluorouracil (5-FU) and imiquimod (IQ). Other treatments such as photodynamic therapy (PDT) are used but to a lesser degree. The evidence for all of these treatments is heterogenous with no randomised data available. Overall up to 57% complete response has been reported with a low number of serious adverse events. In this article, we aim to review the available evidence for the topical treatment of non-invasive penile cancer specifically regarding its efficacy and toxicity.