WASHINGTON, DC-In the hands of skilled Mohs surgeons, the risk of recurrence of squamous or basal cell carcinoma is rare-but if the cancer recurs it may be that the patient is someone with a history of smoking or has immune system issues. Researchers reviewed outcomes in 1,110 patients treated for non-melanoma skin cancer with Mohs surgery from 2008 through 2009 and found that, in 5 years of follow-up there were five recurrences-a rate of 0.45 percent.
"Overall, we found a really low recurrence rate," said Tina Vajdi, BS, a second year medical student at the University of California, San Diego School of Medicine. The recurrences included two squamous cell carcinomas, and both of the patients who had those recurrences had immune system problems. One patient was a lung transplant patient; the other had chronic lymphocytic leukemia, Vajdi said at her poster discussion presentation. Mohs surgeons operated on 357 cases of squamous cell carcinoma, which translated to a recurrence rate of 0.56 percent for that disease.
There were three basal cell carcinomas that recurred, she said. Two of those three patients had smoking histories, as did one of the patients with a squamous cell carcinoma recurrence. Overall, 724 cases of basal cell carcinoma were excised using the surgery technique. That translated to a recurrence rate of 0.41 percent, Vajdi said.
No recurrences were found in the 29 cases of other subtypes of non-melanoma skin cancer, including dermatofibrosarcoma protuberans and atypical fibroxanthoma. All recurrences were located on the cheeks, ears, or nose.
She reviewed the medical records of the patients who were treated at the University of California, San Diego Dermatologic and Mohs Micrographic Surgery Center. For the study, she and her research team defined recurrence to mean the same type of skin cancer that recurred at the same location on the patient. The researchers performed a retrospective chart review of all the Mohs surgery cases, excluding 361 cases because 5-year follow-up was not possible.
"We also reviewed the histopathology and showed that there were no errors in the processing that led to recurrences, and there was no difficulty with the interpretation that led to recurrences for these five cases," she said. All the recurrences occurred on the patients' faces. Recurrences ranged from 11 to 38 months post initial surgery.
"Although recurrences may not be evident in the initial years following Mohs micrographic surgery, we still need longitudinal studies to determine the characteristics associated with these recurrent non-melanoma skin cancers," Vajdi said.
She noted non-melanoma skin cancers are the most common cancer found in patients with fair skin, Vajdi explained. "Mohs micrographic surgery has been used for decades to treat certain high-risk non-melanoma skin cancer due to its high cure rate. Clinical recurrences do occur in a small number of cases; cited as 1 percent in the literature." Patients did not follow up for at least 5 years at the institution were contacted via telephone and asked whether they had further treatments in the location of the initial Mohs surgery.
"As recurrences may not be evident in the years immediately following Mohs surgery, further longitudinal studies are warranted to analyze clinical characteristics associated with recurrences," Vajdi said.
"With the techniques that have evolved, I would even expect to see better results with a lower recurrence rate than even 0.45 percent," said Doris Day, MD, a dermatologist at Lenox Hill Hospital, New York City, "Mohs surgeons in general are really very good. It is just remarkable how much the technique has advanced; how precise and how specific and how accurate it is."
Mohs Procedure
"Mohs surgery is time-consuming but also timesaving and skin-saving because you don't have to go back for more surgery and you also leave with peace of mind, so it is anxiety-saving as well," Day told Oncology Times.
The procedure was developed in the 1930s by the late surgeon Frederic Mohs of the University of Wisconsin. "You do the surgery with relatively conservative but appropriate margins to completely remove the tumor from cosmetically sensitive areas such as the face," Day explained. The removed tissue is examined using an on-the-spot laboratory to process the tissue. It takes about 45 minutes to an hour to go through that whole process of freezing the tissue and then examining it under the microscope.
"If the tumor is too close to the margin or touches the margin, then you don't have to go back and cut out the whole area again, but just the area where there is not a good enough margin," Day said. "When they have an adequate margin, the incision is closed. If the incision is too large, the repair is handed off to a plastic surgeon. It is the best procedure to adequately remove a non-melanoma skin cancer."
She said that she hands off her cases that appear difficult to Mohs surgeons she works with. "Not everyone can do Mohs surgery," Day said. "You need special training, typically 1-2 years of extra training. If you are going to be a Mohs surgeon, it is important that you stay current. The techniques are evolving all the time. This is not a procedure that can be taken lightly."
Day said that in all the patients she has had that have gone to Mohs surgeons she has seen one recurrence, and that occurred to a patient who was initially treated outside of her reference network.
Ed Susman is a contributing writer.