Mohs' Offers
Highest Cure Rate for Some Skin Cancers
March / April 2004
Mohs' micrographic surgery is a precise, tissue-sparing
technique that is most often utilized for skin cancer that
is large, recurrent or located on the face, digits or other
delicate areas. Typically, the surgery is used for basal cell
carcinoma and squamous cell carcinoma, the most frequently
occurring skin cancers. Mohs' has the highest cure rate
available for these two types of cancers and is more effective
than radiation, dissection, and curettage, standard excision
or frozen section. Recent studies have shown that treatment
with Mohs' has a 99 percent cure rate for basal cell
carcinoma and a 97 percent cure rate for squamous cell carcinoma.
Indications for Mohs' include a tumor on the ears,
nose, eyelids, or other part of the face, digits or genitalia
(or another area where one wants to avoid recurrence while
sparing normal tissue), a tumor larger than one to two centimeters
or a recurrent tumor. Every lesion does not require the tissue-sparing
precision and expense of Mohs'. In less apparent parts
of the body (such as the back) surgeons usually remove a wider
margin around the tumor in order to be more confident that
the entire tumor is removed.
The Surgery
In Mohs' surgery, skin lesions are removed one layer
at a time and frozen sections are examined under the microscope
immediately after they are removed. “Unless you are
looking through the microscope you do not know which way the
tumor is growing and, often, there is more tumor than what
you see with the naked eye,” says Chrysalyne
D. Schmults, MD, assistant professor in the Department
of Dermatology at the Hospital of the University of Pennsylvania
specializing in Mohs' surgery. Dr. Schmults and her
colleague Shobana
Sood, MD, both have specialty training in the Mohs'
technique.
While the patient relaxes in the waiting room, the tissue
is examined and the orientation of the tissue is preserved
enabling the surgeon to determine if the tumor is growing
peripherally in any direction or deeper. The patient reenters
the treatment room and additional tissue is removed only in
the area where the margin was positive. Most cases are cleared
in one to three stages, however, larger or recurrent tumors
often require multiple stages.
“Mohs' has a higher cure rate because of the
way we examine the tumor’s margins. Basically, in a
standard frozen section the tissue is cut like a loaf of bread
and the margins that correspond to the cuts closest to the
edge are studied. Because the entire margin of the tumor cannot
be examined, there is always the possibility that not all
of the cancer is removed,” explains Dr. Schmults. “With
Mohs', the surgeon views 100 percent of the surgical
margin, which allows for greater confidence that the margin
is clear. This results in a higher cure rate.”
Dermatopathology
In cases where a second opinion or further expertise is required,
Mohs' surgeons at Penn work closely with Penn dermatopathologists.
Dermatopathologists are physicians who are trained in both
the areas of dermatology and pathology and who specialize
in reading skin biopsies.
“Reading a skin biopsy requires correlation of the
microscopic findings with the clinical findings. It is more
than just looking under the microscope. It involves incorporating
our knowledge of dermatology, drug effects and what cancers
do. It takes the whole patient into account,” says
Jacqueline M. Junkins-Hopkins, MD, dermatologist and dermatopathologist
at Penn. “On occasion when the clinical aspect is added
to what is seen under the microscope the diagnosis completely
changes.”
For example, a biopsy diagnosis of basal cell cancer in
an 80-year-old is quite common, yet similar microscopic findings
noted in a biopsy from a fourteen-year-old might, instead,
represent a benign growth that shows microscopic features
that simulate basal cell cancer. At Penn, some dermatopathologists
have a further subspecialty such as lymphoma (Dr. Junkins-Hopkins’
subspecialty) or melanoma, which allows them to handle some
of the more complicated cases.
“Sometimes it is difficult to determine if there is
cancer remaining. Instead of unnecessarily taking extra margins,
there is an advantage to utilizing special stains that can
further define the tumor and potentially predict a behavior
that is more typical of one type of cancer than another,”
adds Dr. Junkins-Hopkins.
Reconstruction
Depending on the size and location of the tumor that was
removed, patients may require small skin flaps, grafts
or other reconstruction.
Mohs' surgeons receive training in reconstructive surgery
during their fellowship training and are experienced with
repairing skin wounds and defects. “I repair about
90 percent of my Mohs' defects, but if the lesion
is large enough that the reconstruction cannot be completed
under
local
anesthesia, the patient requires a multi-stage reconstruction,
or there are other special circumstances, I rely on the expertise
of the plastic surgeons at Penn,” explains Dr. Schmults.
In addition, Penn basic scientists and dermatologists are
currently researching topical therapies that dissolve some
early skin cancers.
What you need to know about skin cancer and biopsies
- Biopsy a lesion that is growing, changing or not healing.
- Listen to the patient. If the patient thinks the lesion
has grown or changed, it may warrant a biopsy.
- Get a second opinion. With more primary care physicians
performing skin biopsies, it is critical to have the biopsy
interpreted by a dermatopathologist or get a second opinion,
especially if you have concerns clinically.
- Communication is critical to get the best diagnosis. If
the pathology report is negative, but you are clinically
concerned – communicate with the pathologists and
ask them to do further evaluation.
- A biopsy cannot be read in isolation. Clinical information
is often necessary for accurate interpretation by a dermatopathologist.
Some cases are not clear and require more than one biopsy.
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