The prospect of endoscopic submucosal dissection for early anal canal squamous cell carcinoma.

Squamous cell carcinoma (SCC) of the anal canal is seldom diagnosed at an early stage. Chemoradiation therapy is a standard in Europe and the United States, though in squamous cell carcinoma there is no evidence-based therapy. In Japan, endoscopic submucosal dissection (ESD) is the standard minimally invasive treatment for early stage cancer of the digestive tract, including the colorectum. Therefore, if the lesion is diagnosed at an early stage, ESD may be selected for anal canal lesions. We experienced two cases of early stage anal canal cancer in which the diagnosis and the extent of the lesions were confirmed using magnifying endoscopy with narrow-band imaging (NBI), as well as performing ESD. Pathological examination showed the resected specimen to be SCC in situ; the horizontal and vertical margins were free of tumor; and in one case there was no lymphovascular invasion. In the other case it showed the tumor was contained within the epithelium; horizontal and vertical margins were free of tumor; The follow-up period is not long enough to assert that ESD for anal canal squamous cell carcinoma may be an option of minimally invasive therapy. However, if there is a possibility of lymphatic invasion as in one of our cases, we need to give serious consideration to ESD for these lesions, and careful follow-up is necessary even if the lesion is in situ.