A new clinic that treats some skin cancers in a single day has opened at St. Joseph’s Health Centre. Using the Mohs micrographic surgery procedure, the physician removes cancerous growths and tests the tissue on the spot, repeating the process if necessary until the tumour is removed entirely.
“Basal cell and squamous cell are the most common forms of skin cancer, and that’s what we treat here,” says Dr. Erin Dahlke, the St. Joseph’s dermatologist who leads the new Mohs clinic, that was made possible thanks to the support of generous donors, many of them grateful patients, in partnership with the hospital’s Medical Education Teaching Clinic.
“Left untreated, they can lead to metastasis, disfigurement and death — and the incidence is on the rise for several reasons, including a depleted ozone layer and an aging population,” Dr. Dahlke adds. “So it’s great to be able to offer this treatment. My patients come in with cancer, and go home without it.”
Mohs micrographic surgery not only delivers impressive cure rates — 99 per cent for primary tumours, 94 to 95 per cent for ones that have been previously irradiated or treated — but it’s also relatively fast and cost effective. The procedure is done in an outpatient setting, requiring no hospital stay, and the physician also acts as the pathologist.
“I do the surgery and I also read the slides,” says Dr. Dahlke. “It’s great for the patient, and it’s really satisfying for me to be able to provide this service.”
The Mohs procedure involves Dr. Dahlke removing the tumour and as little of the surrounding healthy tissue as possible to minimize disfigurement and scarring. The tissue is then flash frozen and examined under a microscope while the patient waits.
“The removed tissue is processed in a way wherein the entire periphery can be examined,” Dr. Dahlke explains. “That’s why our cure rates are higher than other techniques, because we check the entire periphery and depth. That’s what makes Mohs unique.”
If she sees any tumour cells on the edges of the tissue, Dr. Dahlke will go back and take a bit more tissue.
“The patient might go back to the waiting room once or twice more, because we keep taking the smallest amount possible and checking the margins,” she says. “It’s extremely precise. By the end of the day, we’ve confirmed that the margins are clear, there’s no tumour left and I’ve taken the least amount of normal tissue possible.”
William Hanley, one of the first patients treated at the clinic, came in because of a growth on his face that had not responded to conventional treatment.
“They can give a biopsy result in 45 minutes, which is fantastic,” Hanley says. “You’re not waiting around for a week or more, as you would if something had to be sent out to be tested.
“For me, it took three sessions before it was clear,” he adds. “It can be a long process, but at least you know it’s going to get done that day, which is great.”
Dr. Dahlke sees her patients about a week after their surgery to make sure they’re healing well.
“Removing the tumour in its entirety is the top priority, and Mohs surgery is best for this as it provides the highest cure rates,” she says.
“The next step is providing the best possible esthetic results. This means performing reconstructive surgery, flaps and grafts to avoid distortion of surrounding structures and minimizing scarring,” she adds. “I like to see my patients back at one week and again at two months to ensure everything is healing as it should be.”
Once a patient has had one basal cell carcinoma, they have about a 50 per cent chance of getting another one in the next five years, says Dr. Dahlke.
“So patients do need followup monitoring — if not with their dermatologist, then with their family doctor.”
Another benefit of the Mohs clinic, Dr. Dahlke points out, is that St. Joseph’s community members dealing with tenuous housing or homelessness will be able to get the care they need.
“There is evidence that skin disease tends to go untreated longer in marginalized populations,” she says. “I know there’s a need for outpatient treatments in our local community, and to be able to treat everyone with skin cancer in the best possible way is something I’m excited about.”
Dr. Dahlke also looks forward to building St. Joseph’s dermatology division, and working within the new Unity Health Toronto network to offer Mohs procedures to St. Michael’s Hospital’s kidney transplant recipients, who are at high risk for skin cancer.
“I want to build the education component and expand the dermatology division moving forward,” she says. “And through our partnership with St. Michael’s, I’m looking forward to how we integrate and build our division together.”
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