PEER-REVIEW | SKIN CANCER SURGERY |


In addition to its outstanding safety record, Mohs surgery


also provides excellent cure rates due to the removal of all affected cells.


Dr Mohs developed a paste made


of zinc chloride that could be applied to the area of the tumour, allowing him to excise the tissue without inducing bleeding. This technique did not alter the structure of the skin during the process, which took many hours until the tissue was ready for cutting. Once the area was removed, it was sliced into sections, dyed in order to differentiate the sections and intricately mapped to identify the location from which it was removed. Drs Theodore A. Tromovitch and Samuel


Stegman at the University of San Francisco (UCSF) helped in the evolution of this process; instead of using the zinc chloride paste that was time consuming and painful for patients, they began freezing sections of tissue after excision. This frozen tissue method is what is used today and referred to as Mohs micrographic surgery. Once the tumour is removed with a small margin, it is cut, dyed, frozen, and made into slides. This process expedites the procedure as a whole, as the frozen sections can be processed in a short period of time (usually about one hour per layer), which allows a tumour to be removed in one day rather than several. The traditional paraffin embedded layers take 24 hours to process, extending the treatment period over several days. Most patients see an advantage in receiving treatment over a few hours rather than over a period of days. With local anaesthesia there is minimal pain and bleeding associated with Mohs. After creating the slides, the next step is for the Mohs


surgeon to review them in order to identify whether there are any cancer cells remaining in the margin. In Mohs, 100% of the cut edge is reviewed as opposed to other methods of removal, where only a sampling of this edge is studied. This 100% review of the tissue gives the surgeon great confidence about whether the entire lesion is removed. Additionally, the use of colour-coded mapping of the excised tissue specimen has helped improve the technique and procedure. Another important differentiator is that the Mohs


surgeon also acts as the pathologist, which is beneficial because the surgeon then has a clear image of the pathology and mapping when they return to the patient to take another layer, thus allowing them to remove very small amounts of additional tissue. If cancer cells are still present, an additional small margin is taken and the process is repeated until the margins are clear of cancer cells. Once clear, the open wound can be closed by the Mohs surgeon. The area can then be reconstructed to ensure the best cosmetic outcome and the smallest possible scar. It is for these reasons that Mohs is the best


22 ❚


option for removing lesions that are in cosmetically sensitive areas or areas that would benefit from removing less tissue for functional reasons, like the eyelids or hands.


Safety and survival rates A study conducted by the Cutaneous Oncology Research Cooperative indicated that Mohs surgery sets a new standard of safety in skin cancer treatment7


patients and demonstrated zero incidences of major complications; only 2.6% had minor complications


(bleeding or infection). In addition to its outstanding safety record, Mohs surgery also provides excellent cure rates due to the removal of all affected cells. According to Dr Isaac Neuhaus, dermatologic surgeon at UCSF’s dermatologic and laser center, Mohs surgery has a 5-year cure rate of


99% for new skin cancers and 95% for recurrent skin cancers. This is significantly higher than other methods.


Key points Mohs was first


performed as chemosurgery. It was developed in 1956 and used more widely beginning in the 1970s


Mohs provides the


best option for removing tumours in areas where tissue must be preserved for functional and aesthetic purposes


Provides benefit of


surgeon also functioning as pathologist


Procedures can be


completed in one visit rather than over several days and multiple visits


Mohs provides the


lowest rates of tumour recurrence


References


1. Stern RS. Prevalence of a history of skin cancer in 2007: results of an incidence-based model. Archives of Dermatology 2010; 146(3): 279–282


2. Rogers HW, Weinstock MA, Harris AR, et al. Incidence estimate of nonmelanoma skin cancer in the United States, 2006. Archives of Dermatology 2010; 146(3): 283–7


3. Robins P, Ebede TL, Hale EK. The Evolution of Mohs Micrographic Surgery: The Single Most Effective Skin Cancer Treatment. New York: The Skin Cancer Foundation, 2014. Available at: www.


skincancer.org/skin-cancer-information/ mohs-surgery/evolution-of-mohs [Last accessed 12 December 2015]


4. Rogers HW. ‘Your new study of nonmelanoma skin cancers’. Email to The Skin Cancer Foundation. March 31st 2010


5. Squamous Cell Carcinoma. American Academy of Dermatology. Schaumburg, IL: AAD, 2014. Available at: www.aad.org/ skin-conditions/dermatology-a-to-z/ squamous-cell-carcinoma [Last accessed 12 December 2015]


6. Zitelli JA, Mohs FE, Larson P, Snow S.


Mohs micrographic surgery for melanoma. Dermatologic Clinics 1989; 7(4): 833–843


7. Merritt BG, Lee NY, Brodland DG, Zitelli JA, Cook J. The safety of Mohs surgery: a prospective multicenter cohort study. Journal of the American Academy of Dermatology 2012; 67(6): 1302–9


8. Saladi RN, Persaud, AN. The causes of skin cancer: a comprehensive review. Drugs of today 2005; 41(1): 37–53


Declaration of interest None


Protection is best Although not the only cause of skin cancer, UV exposure is undeniably linked to the development of this disease8


.


Therefore, comprehensive efforts to avoid unnecessary exposure should be made. Daily use of a broad spectrum sunscreen with an SPF of at least 30 is critical. It should be applied 30 minutes prior to exposure and reapplied every 2 hours thereafter, or after swimming or perspiring. Sun avoidance strategies such as refraining from exposure between the hours of 10 am and 4 pm when UV rays are strongest, and wearing a wide-brimmed hat and protective clothing will certainly help patients minimise their chances of developing skin cancer. Mohs micrographic surgery has continually


demonstrated its benefits as the gold standard in skin cancer care. It has excellent survival rates and leaves the patient with minimal visible scarring.


. The study had 1,550


January/February 2015 | prime-journal.com


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