Mohs Surgery - Comparison To Other Modalities of Treatment

Comparison To Other Modalities of Treatment

Mohs surgery is not the answer for all skin cancers. Under select circumstances, radiation, topical chemotherapy, cryosurgery, electrodesiccation and curettage, and standard excision are better than Mohs surgery. Studies comparing the effectiveness of Mohs surgery to other modalities often fail to specify surgical margin, method of processing (bread loafing with 3 or 4 sections, bread loafing with 0.1 mm spacing, margin controlled, frozen section vs. standard histology); leaving little argument one way or another. Once a pathologist understands the simplistic nature of Mohs surgery, and its margin control ability – little need is called for clinical trial comparing Mohs surgery to surgical excision.

In reality, Mohs micrographic surgery is nothing more than frozen section histology using a unique peripheral margin control tissue processing technique. There is nothing magical about its cure rate or why years of training is required. When compared to many other described peripheral margin control tissue processing technique – the end result is the same – allowing for the complete examination of 100% of the surgical margin. The method is unique only in that it is a simple way to handle soft, hard to cut tissue. Once learned, any pathologists currently doing frozen section histology would realize how simple the technique is. It is better than doing serial bread loafing at 0.1 mm interval for improved false negative error rate simply in requiring less time, less tissue handling, and fewer glass slides mounted. Once mounted as tangential or horizontal sections, the pathologist simply has to relearn how to visualize skin structure on a tangential to horizontal view. In absent of a Mohs trained pathologist, peripheral sectioning followed by horizontal sectioning of the remaining center is equivalent to the Mohs method.

The clinical quotes for cure rate of Mohs surgery is from 97% to 99.8% after 5 years for newly diagnosed basal cell cancer, decreasing to 94% or less for recurrent basal cell cancer. Radiation oncologists quote cure rate from 90 to 95% for BCC's less than 1 or 2 cm, and 85 to 90% for BCC's larger than 1 or 2 cm. Surgical excision cure rate varies from 99% for wide margin (4 to 6 mm) and small tumor, to as low as 70% for narrow margins applied to large tumors. Here the weakness of the procedure is the histopathological processing, and not the surgeon himself. The fault of the surgeon is lack of understanding pathology laboratory methods, and failing to follow the standard of care for adequate surgical margin. Usually the cure rate using standard bread loafing is very low for narrow surgical margin and a large tumor, and very high for large margins on small tumors. It is the pathology lab that makes the difference, especially when frozen section is utilized in the operating theater. A randomized study assigning patients with recurrent facial basal cell cancer to either Mohs surgery or standard excision revealed no statistical difference in the treatment of primary basal cell carcinoma. It found a higher cure rate with Mohs surgery in the treatment of recurrent basal cell carcinoma (5 year recurrence rate of 2.4% for Mohs vs 12.1% for standard).

Cosmetic appearance for Mohs surgery is very good, if combined with good reconstructive surgical skills. Some Mohs surgeon utilize a plastic or reconstructive surgeon for the closure, and some Mohs surgeons perform the reconstruction by themselves. In certain area, the tip of the nose, and the nasal ala, Mohs surgery can result in significant deformity, and might require multiple staged reconstruction to rebuild the nose cosmetically. Radiation offers a very good non-traumatic option in these difficult to reconstruct areas.

In choosing a Mohs surgeon or reconstructive surgeon, it is mandatory that a patient request to see pictorial representation of his/her previous work. Then one can proceed to make a decision whether the Mohs surgeon should also be the reconstructive surgeon.