Mohs micrographic surgery offers an excellent option for treating skin cancers, resulting in less scarring and an impressive cure rate.
Which group of cancers this year will strike more Americans than all other cancers put together?
The answer may be right under your nose--or right on it.
They are nonmelanoma skin cancers, most of them basal cell and squamous cell carcinomas of the skin. The American Cancer Society estimates that 1.3 million new diagnoses of these cancers will be made this year, higher than the 1.2 million diagnoses of all other cancers combined.
Good news, though: the cancers are often preventable, and highly curable if detected and treated early, says Judy K. Chiang, M.D., assistant professor of dermatology at the Keck School of Medicine of USC.
Chiang, the newest member of the skin cancer team at the USC/Norris Comprehensive Cancer Center, recently brought the advanced surgical technique called Mohs micrographic surgery to USC. Named after Frederic Mohs, M.D., who developed the technique in the 1930s, the surgery allows the selective removal of areas involved with skin cancer while preserving as much of the surrounding normal tissue as possible. The procedure, when performed by a Mohs-trained surgeon, cures about 95 to 99 percent of cases, even if other forms of treatment have failed. Furthermore, cosmetic results are maximized as this technique spares as much normal tissue as possible.
"When you finish a Mohs procedure, you can tell the patient that they are microscopically clear of the tumor," says Chiang, who recently came to USC from Vanderbilt University Medical Center in Tennessee. "And that's reassuring."
But before talking about how to treat skin cancer, Chiang says it is critical to understand what it is.
"Most people are much more aware of melanoma than nonmelanoma skin cancer, the most common skin cancer," she says. "It's important to be aware of nonmelanoma skin cancer, as it is curable if caught early."
The skin is the largest organ in the body. The top layer of skin is the epidermis. The bottom layer of the epidermis is called the basal cell layer, and it is the starting point for basal cell carcinoma, which accounts for about 80 percent of nonmelanoma skin cancers. Squamous cell carcinomas start in the upper layers of the epidermis, and they make up about 15 percent of nonmelanoma skin cancers.
Unlike melanoma, which tends to metastasize and spread aggressively in the body, nonmelanoma skin cancers such as basal cell and squamous cell carcinomas tend to grow more slowly. They can be locally aggressive, growing into nearby vital structures such as the eyes and nose, but rarely spread to distant organs.
Basal cell carcinomas usually develop on areas that are exposed to the sun such as the scalp, face and neck, though they can also appear on protected areas. Squamous cell carcinomas are similar, commonly appearing on the nose, ears, lips and back of the hands. They also can develop within scars.
"Patients often describe basal cell carcinoma as a pimple that bleeds and does not go away," she notes. "It often appears as a pearly pink papule." But not all cancers follow the textbook: There are several variants including some that can be flat and hard; others raised, crusted and scaly. Chiang cautions that any new skin growth or a change in a growth or lesion that does not go away should be checked by a dermatologist.
Besides basal cell and squamous cell carcinomas, Mohs micrographic surgery also has been used for rarer conditions of early stage melanoma and rare forms of nonmelanoma skin cancers such as microcystic adnexal carcinoma and dermatofibrosarcoma protuberans.
Once a doctor has biopsied a skin lesion and found cancer, Chiang sees the patient to assess whether Mohs surgery is the right choice.
Mohs surgery is a good option for someone whose tumor is on the face, she says. And here's why: In the traditional way of removing these cancers, a physician surgically removes the tumor with standard margins, which often sacrifices normal tissue. On the face, especially near the eyelids, lips and nose, any normal tissue free of cancerous cells should be spared, as it is crucial in getting optimal results in reconstruction.
In the specialized Mohs technique, Chiang first debulks the visible part of the tumor. Then she excises a thin layer of skin. This specimen is mapped using special colored dyes, divided into sections and processed by a technician.
Chiang leaves the operating room to look at the skin samples under a microscope, noting any areas where she sees cancerous cells. If the specimen is positive, she returns to the patient and removes another thin layer of skin only from the area that showed evidence of remaining cancer. Again, this new skin sample is processed and examined for cancer cells under the microscope. The process is repeated until no more cancer can be found. Chiang then reconstructs the defect using primary closure, flaps or grafts.
By using this technique, Chiang can selectively remove tissues that are positive for cancerous cells.
"It provides the highest degree of confidence in the removal, and takes away the least amount of normal, healthy skin," notes Arnold Gurevitch, M.D., USC professor and chief of dermatology.
"Mohs is also one of the best ways to treat recurrent tumors," Chiang says. Other indications for Mohs surgery include large lesions, tumors near vital, functional or cosmetic parts of the body such as the face, or aggressive-type tumors.
Mohs surgery is highly effective when done by a certified Mohs surgeon, she says, with recurrence rates less than two percent. Dermatologists certified to do Mohs surgeries have undergone a three-year dermatology residency followed by a one-year fellowship in Mohs micrographic surgery. Chiang and other Mohs specialists are members of the American College of Mohs Micrographic Surgery and Cutaneous Oncology.
"But not everyone needs Mohs," she explains. The procedure has its disadvantages: it is time- and labor-intensive. Each break to examine slides takes about 30 to 60 minutes, and the entire procedure can take a half-day or more to complete, she says.
"If the tumor is on your arm or leg, and it's a small, superficial basal cell carcinoma, then there are other options to consider such as general excision, with margins-since sparing normal tissue is not a major concern in these areas-electrodesiccation and curettage, cryotherapy, and topical chemotherapy," she says.
For many patients, though, Mohs micrographic surgery is the procedure of choice. And Chiang enjoys the ability to bring that option to people.
"One of the main reasons I like Mohs is that I can do something for my patients," she says. "The cure rate and patient satisfaction after Mohs surgery are extremely high."
Gurevitch says that Chiang, a graduate of the Baylor College of Medicine, brings her "positive personality" to dermatology at USC. "She expands the range of dermatology here and provides a unique service," Gurevitch says. "We see quite a few patients with cancers that are perfect for Mohs treatment."
For more information about Mohs micrographic surgery, or to learn more about The Doctors of USC, call 1-800-USC-CARE (1-800-872-2273).