Post written by Michael Lajin, MD, from SHARP HealthCare, San Diego, California, USA.

The standard treatment for squamous cell anal cancer is chemoradiation treatment. A few case reports from Japan address resecting early squamous cell anal cancer by endoscopic submucosal dissection (ESD). We presented a case series of squamous carcinoma in situ of the anal canal resected with ESD in a western population.

The lesions in cases 2 and 3 were resected using the pocket creation method, which allows for preserving the fluid in the submucosal space, resulting in an easier and more efficient dissection, particularly in difficult anatomical locations such as the anal canal. 

On the other hand, the lesion in case 1 was a wider lesion. The conventional method was selected in this case because it enables marking off the dissection endpoints at the borders of the lesion.  

The initial mucosal incision was started at the anal side. This approach allowed us to perform the initial submucosal dissection with a straight rather than a retroflexed endoscope position.   

In addition, the incision at the anal side is more difficult. Thus, it is preferable to start with detaching that side first. ORISE Gel (Boston Scientific, Marlborough, Mass, USA) was the injection solution used in all cases because of its ability to provide a long-lasting submucosal fluid cushion. 

Successful en bloc resection was achieved in all patients. The ESD pathology was consistent with a high-grade squamous intraepithelial lesion (AIN-3) without invasive cancer. All patients had R0 resection with free margins, and they are clear from dysplasia/malignancy on their latest endoscopic surveillance ranging from 10 to 26 months after ESD. 

Because the pathology of the resected lesions is consistent with AIN-3 with free margins, all 3 patients are undergoing regular endoscopic surveillance, and no further treatment is warranted at this time. There were no immediate or delayed adverse events, such as bleeding, perforation, infection, stenosis, or fecal incontinence. 

In conclusion, ESD can be utilized to resect squamous cell carcinoma in situ of the anal canal. Larger studies with long-term follow-up are needed to evaluate the role of ESD in early squamous cell anal cancer and to compare it with other modalities of treatment. 

I want to emphasize the importance of careful inspection of the distal rectum and the anal canal to detect early squamous cell cancer. These lesions can be very subtle and could easily be missed. 

Case 1: Pre–endoscopic submucosal dissection narrow-band image of anal intraepithelial neoplasia-3 lesion.

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