Mohs surgery experts advise when Mohs is and isn’t optimal skin cancer treatment.
Whether a skin cancer patient is or isn’t a good candidate for Mohs isn’t always clear cut.
A panel of experienced Mohs surgeons tackled the topic “To Mohs or not to Mohs,” during the American Academy of Dermatology Summer Scientific Sessions in Boston. The panel’s director Richard Gary Bennett, M.D., clinical professor of medicine (dermatology), UCLA, and clinical professor of dermatology at University of Southern California (USC), says there is an important new document that helps dermatologists in their decision making.
Dr. Bennett“There are guidelines1 for Mohs surgery … developed by the American Academy of Dermatology in conjunction with the American Society for Dermatologic Surgery. And those guidelines basically try to quantitate, if you will, what the appropriateness of doing Mohs surgery is in certain case scenarios,” Dr. Bennett says.
The production and adoption of these first Mohs guidelines by the AAD and ASDS started about four years ago, according to Suzanne Olbricht, M.D., chair of dermatology at Lahey Hospital and Medical Center, Burlington, Mass., incoming president elect of the American Academy of Dermatology and a panel member at this session at the AAD’s summer meeting. The Mohs guidelines’ authors used a modified RAND/UCLA Appropriateness Method to develop appropriate use criteria for basal and squamous cell skin cancers. To accompany the desk top document, there is a "Mohs Surgery Appropriate Use Criteria" app, which dermatologists and others can access on their mobile devices.
The interactive app2, with free download, offers decision support on Mohs appropriateness in 270 scenarios, color-coded body maps for low- to high-risk areas and more. Doctors can enter the tumor type, size and other information to get an appropriateness score.
As helpful as the guidelines and app are, they are not the end-all of decision making, according to Dr. Bennett.
“The case scenarios [in the guidelines] are not totally inclusive,” Dr. Bennett says.
Among the important issues the guidelines do not address are age or skin cancer patients’ comorbidities, he says.
In real world practice, that means Mohs surgery might not benefit a 98-year-old patient with a basal cell on his nose; whereas, it will likely benefit a 30-year-old with the same cancer diagnosis. And, while the high cure rate of Mohs will likely be in an otherwise healthy patient’s best interests, that might not the case for a patient who has only a year or two to live, according to Dr. Bennett.
Chrysalyne Delling Schmults, M.D., associate professor of dermatology, Harvard Medical School, says the Mohs practice at Brigham and Women’s Hospital has evolved towards not doing Mohs for epidermal basal cell and squamous cell in situ tumors, unless they’ve already failed some other treatment.
Dr. Schmults“We’ve been doing it this way for several years now. In our hands, we get a 90% cure rate with topical treatments, primarily topical 5-Fluorouracil (5FU) and imiquimod. And this is backed up by a randomized controlled trial for superficial basal cell cancer which showed cure rates of 80% to 83%-particularly with imiquimod and 5FU for superficial basal cell cancer,” Dr. Schmults says.3
The 90% cure rate that Dr. Schmults and colleagues have achieved at Brigham and Womens Hospital with topicals is on the high end of the 80% to 90% cure rate in the literature, she says.
“That’s probably because we are selecting patients for topical treatments who want topical treatments and are going to be compliant with them. In a randomized study, you’re going to have some people who are more compliant than others. But in our case where most patients treated topically are highly motivated to avoid surgery, our cure rates are very high,” Dr. Schmults says.
Still, 90% is lower than the cure rates from Mohs, which tend to be 98% to 99%, but using topicals avoids some Mohs-associated side effects, including scarring, according to Dr. Schmults.
“There’s no downside to trying the topical treatment, because if you do end up being in that 10% to 20% who are going to have a recurrence, you still have surgery as your option. These epidermal cancers are not going to metastasize. If it grows back, then you just treat it surgically,” Dr. Schmults says.
Where Mohs shines, according to Dr. Schmults, is for dermally invasive tumors, which are not going to clear with a topical approach and need a surgical incision.
“If it’s a small tumor, on the trunk (not a cosmetically sensitive area), we’ll do a disc excision and usually let it granulate. But once you have a dermally invasive tumor, I like to know histologically that the tumor is out. So for small [tumors], I’m comfortable with disc excision, but for anything larger or anything on the head, face, hands, lower leg-areas where you want to have some tissue conservation-then, I don’t see a reason not to do Mohs and getting complete histologic clearance. You’re getting very accurate margins, with a very high cure rate. You’re also giving somebody an optimal cosmetic result,” Dr. Schmults says. “The only reason not to do it is because it costs more in some cases than a standard excision.”
Mohs, according to Dr. Schmults, should be the standard of care for the more aggressive tumors.
“In high-stage squamous cell tumors treated at Brigham and Women’s Hospital, a high fraction of the cases that didn’t get Mohs surgery and had standard excision never achieved a clear surgical margin,” Dr. Schmults says. “I think this is because a lot of these high stage squamous cell cancers are very infiltrative, with a lot of perineural spread and a lot of single cell spread at the perimeter. You need the accuracy of total margin control to really clear these tumors surgically.”
In the case of Mohs, adjunctive treatments refer to treatments that shrink tumors before Mohs, with a chemotherapeutic agent or radiation.
“Sometimes, lentigo maligna is treated with a chemotherapeutic agent (usually imiquimod) before or even instead of surgery, or after surgery, when suspicious margins are still present, the site is treated with the agent. For dermatofibrosarcoma protuberans, some physicians may use imatinib to make it smaller before the Mohs surgery,” Dr. Olbricht says.
In rare cases, Mohs surgeons use vismodegib (Erivedge, Genetech) instead of doing surgery for basal cell carcinoma.
Mohs surgeons might also irradiate an area after surgery, if the cure rate for that particular tumor with Mohs isn’t as high as they’d like, Dr. Olbricht says.
“For the average primary basal cell or squamous cell, the cure rate for Mohs surgery is 98 to 99 percent. But we know, under some circumstances, for instance perineural tumor, the cure rate with Mohs is less, so that maybe we want to also irradiate the site after surgery to try and reduce recurrence,” she says.
Dr. Schmults says there are ways around the added costs associated with Mohs. For example, when patients have multiple tumors, the cost of doing Mohs on that second or third tumor the same day is in most cases less expensive than if they were getting it excised by their dermatologist on a different day.
“In that case, it’s not even more expensive to the system to do Mohs. It’s actually the same cost or even cheaper for the system, and you can get these treated for a patient on a single day, in a single visit, which makes it more convenient for the patient,” she says. “In these cases, why would you not do Mohs?”
Dermatologists confronted with skin cancer patients should use the guidelines as a guide, along with common sense, according to Dr. Bennett. They should be aware, however, that treating patients outside the guidelines could result in payment denials.
Payment challenges can occur, according to Dr. Olbricht, when a pathology report comes back with a non-cancerous diagnosis or one that doesn’t fit the criteria for Mohs but the dermatologist has his or her doubts and thinks Mohs is indicated.
“The pathologist can’t always know when it’s benign or malignant. Yet the insurance company will take the pathologist’s view,” Dr. Olbricht says.
Disclosures: Bennett, Richard Gary, MD: no financial relationships exist with commercial interests. Olbricht, Suzanne, MD: no financial relationships exist with commercial interests. Schmults, Chrysalyne Delling, MD: Dermatology Foundation – I(Grants/Research Funding); Genentech, Inc. – I(Grants/Research Funding); Novartis Pharmaceuticals Corp. – I(Grants/Research Funding).
1. Guidelines for Mohs surgery, from the American Academy of Dermatology in conjunction with the American Society for Dermatologic Surgery:
2. Mohs Surgery Appropriate Use Criteria app: