Mohs Surgery for Treating Squamous Cell Carcinoma in Situ

In this interview, Dr Ramone Williams discusses her session, “Pro and Con: Contentious Concepts” at the 2023 ACMS Annual Meeting. She covered the topic, “Mohs vs Topical Therapy for Squamous Cell Carcinoma in Situ (SCCIS): Pro Mohs.”

Ramone F. Williams, MD, MPhil, is a Mohs surgeon at Massachusetts General Hospital and an instructor at Harvard Medical School in Boston, MA.

The Dermatologist: Can you give us a recap of what was covered during your session at the 2023 ACMS Annual Meeting?

Dr Williams: Specifically, my topic was Mohs vs topical therapy for SCCIS, and my position was pro Mohs surgery. In general, I covered the benefits of Mohs surgery for patients diagnosed with SCCIS.

The Dermatologist: What are the advantages of Mohs micrographic surgery over topical therapy when it comes to treating SCCIS?

Dr Williams: There are a variety of advantages for the use of Mohs surgery for SSCIS, or Bowen disease. In particular, Mohs offers immediate margin control before the patient leaves the office. You have the advantage of letting them know that they are clear of their skin cancer. In addition, Mohs is a tissue sparing procedure; this is particularly important on sensitive areas, such as the eyelids, nose, ears, and other areas that are considered high risk. Mohs offers superior efficacy with very high cure rates, and it is effective in the case of more aggressive types of squamous cell carcinoma, which may have been upstage from an initial biopsy of SSCIS.

The Dermatologist: Are there any limitations to using Mohs surgery for SCCIS? If so, what are they?

Dr Williams: Yes, not every patient may be appropriate for Mohs surgery. Some patients may be poor surgical candidates for a variety of reasons. However, in general, Mohs is considered a very low-risk surgery and even older patients with multiple comorbidities are good candidates for Mohs surgery.

The Dermatologist: How effective is Mohs micrographic surgery in treating SCCIS compared with topical therapy?

Dr Williams: Mohs is considered to have superior efficacy compared to topical therapy. Mohs offers very high cure rates. The data on this are limited, but it is thought that the recurrence rate for SCCIS following Mohs surgery is quite low.

The Dermatologist: Can you discuss any potential risks or side effects associated with Mohs micrographic surgery for SCCIS?

Dr Williams: Mohs surgery, in general, is considered a low-risk procedure. However, any surgical procedure does have risks. The risk may be individualized to the patient and to the particular surgical scenario. When we think about surgery, we think about risks such as bleeding, infection, and scar. There may also be damage to surrounding structures during surgery as well.

The Dermatologist: What factors should be considered when determining whether Mohs micrographic surgery or topical therapy is the best treatment option for SCCIS?

Dr Williams: Every clinical scenario is different; every patient is different. We are fortunate that we have a variety of guidelines to guide our treatment choices as surgeons and cutaneous oncologists. For example, we have our NCCN [National Comprehensive Cancer Network] guidelines as well as our AEC [appropriate use criteria] guidelines. These help inform our decision-making.

In literature review, I did find a variety of factors that should be considered when deciding how to treat SCCIS. For example, a biopsy report with a transected base should really pique the interest of the treating provider. This should be a red flag that this tumor actually may be deeper than previously thought. There are other factors as well. For example, if the patient is immunocompromised, that is another risk factor to consider. Those patients have a higher risk of recurrence as it relates to SCCIS.

The Dermatologist: Can you go over the key points from the session in detail?

Dr Williams: I reviewed the benefits of Mohs surgery for SCCIS and decision-making in general when it comes to treating SCCIS. Some factors that are important to consider are the risk of occult invasion for SCCIS; this risk is actually higher than previously thought. Previously, we have been told that the risk of invasion is around 3% to 5%; we have more recent data that tell us this rate is actually much higher, around 10% to 16%. I also reviewed data in my talk that upstage SCCIS can at times be more aggressive, which in many cases would make Mohs the more appropriate option. I also discussed that SCCIS with a transected base should be really carefully considered, and surgeons and cutaneous oncologists really need to consider whether or not the biopsy is an accurate representation of the tumor that the patient has. And, lastly, I reviewed that immunosuppressed patients have a higher risk of recurrence. Mohs offers superior margin control in many of the scenarios that I have outlined and should be considered depending on the clinical scenario and other patient factors.

Reference:
Williams RF. Pro and con: contentious concepts. Presented at: American College of Mohs Surgery (ACMS) Annual Meeting; May 4–7, 2023; Seattle, WA.

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