Review MOHS SURGERY -The Myth and the Truth- Tsu-Yi Chuang Since Dr. Frederic E. Mohs invented the Mohs Surgery in 1936, Mohs Micrographic Surgery (MMS) has been utilized by many to remove ill-defined basal (BCC) and squamous cell carcinomas (SCC) at difficult anatomic sites like nose, ears and so-called H-zone of the face. However, more and more Mohs surgeons began to claim that Mohs technique should be applied to all skin cancers and be the standard of care because: (1) MMS has the highest cure rate for skin cancer: the recurrence of BCC after MMS is < 1%; (2) MMS is the most cost-effective management for skin cancer; (3) MMS can maximize the preservation of normal tissue and (4) MMS can remove melanoma in the most precise and complete way and thus should be the standard of care for melanoma. That s the myth. We should look into the truth. Even though Mohs surgeons could cite a low recurrent rate after excising primary BCC, about 1.5%, surgical excision, electrodessication and curettage, and cryotherapy all might come up with a low recurrence of 3%, 4% and 3%, respectively. A BCC could be excised by traditional surgical excision with 60% less cost than by MMS. Further, if avoidance of a recurrence should be the prime goal of using MMS for all aggressive BCC, it should command more than $30,000 just to avoid one recurrence. But such a recurrence could easily be handled with less than $1,500. It might be a tough job to maximize the preservation of normal tissue for any Mohs surgeon. They actually advocated removing more tissue for melanoma in situ for the sake of complete clearance. They would have to sacrifice more normal tissue anyway to obtain the best cosmetic result after MMS. It would be difficult to delineate the margins of melanoma on frozen sections for Mohs surgeons lacking formal pathological training to begin with. The frozen sections were called unreliable for evaluating the margins by most experienced pathologists. Further, there was no evidence to support the notion that MMS was better than traditional surgical excision in lessening recurrence and metastasis. Mohs surgery should be seen as a valuable technique in clearing BCC/SCC at difficult anatomic and in cleaning up aggressive and ill-defined BCC/SCC. But this technique has its intended goal and specific target. (Dermatol Sinica 26: 1-9, 2008) Key words: Mohs surgery, Myth, Truth From the Desert Specialty Group, Inc., Rancho Mirage, California and the Department of Dermatology, University of Southern California, Los Angeles, California Reprint requests: Tsu-Yi Chuang, M.D., M.P.H., Professor Desert Specialty Group, Inc. 69-844 Hwy 111, Suite A Rancho Mirage, CA 92270, U.S.A. TEL: +1-760-318-4869 FAX: +1-760-770-1608 E-mail: chuang004@gmail.com 1
Tsu-Yi Chuang HISTORY OF MOHS SURGERY The Mohs Surgery was invented in 1936 by Dr. Frederic E. Mohs, a general surgeon, at the University of Wisconsin, Madison. While he was studying in vivo inflammatory response in transplantable rat cancers to various injectable irritants, Dr. Mohs noted that injected 20% zinc chloride solution inadvertently caused tissue necrosis in cancer and the necrotic tissue microscopically showed well-preserved cancer and cell histology, the same as if the tissue had been excised and immersed in a fixative solution. He began the experiment of applying a modified 20% zinc chloride fixative paste directly to the skin cancer of the patient for fixation of tissue and 24 hours later, the fixed skin cancer was surgically removed by using horizontally oriented section without local anesthetic. It was then examined microscopically for clear margins. This discovery formed the basis for a method by which cancers could be excised under complete microscopic control. Long-term follow-up of his patients was carefully documented and gave further testimony to the effectiveness of this treatment. In 1941, Dr. Mohs published his results using this chemosurgery as it was called originally, or later, fixed tissue technique, to remove basal cell carcinomas (BCCs) from 440 patients in which he obtained a 99% cure rate for primary cancers and a 95~96% cure rate for recurrent cancers. 1 He created a unique mapping process that assisted in orienting the excised and colorcoded tissue back to the patient. This chemosurgery technique was understandably very painful and could only perform one stage a day. 1953 was the year when Dr. Mohs found out that using local anesthetic and horizontal sections could expedite the procedure and be more effective and efficient. Thus, the fresh-tissue technique of Mohs chemosurgery was created. But for decades, Dr. Mohs had been a pioneer, advocator and a lone practitioner performing this unique procedure. The breakthrough came in 1970, when Dr. Theodore Tromovitch presented his experience of using the fresh-tissue technique of Mohs surgery, in which he omitted the use of zinc chloride paste, used local anesthetics and substituted with frozen sections. This way, he could perform multiple stages in one day and repair the defect as soon as the tumor free margins are achieved. Then in 1974, the use of the fresh-tissue technique increased when preliminary reports by Drs. Tromovitch and Stegman regarding the use of Mohs surgery to treat BCC demonstrated no recurrence in 97% of patients (in 99 of 102). 2 This was a confirmation of Mohs technique accomplished by Dr. Mohs 30 years earlier. In 1986, the technique was formally called Mohs Micrographic Surgery (MMS) (Figs. 1 & 2). Trained as a Mohs Surgeon From the 1950 s to the 1970 s, Mohs surgical training was conducted on an informal basis. Training sessions usually lasted from several days to weeks. Some trainees were sometimes called weekend warriors because of training and observation being conducted during weekends for the convenience of busy dermatologists. Some training last for months for serious learners but all took place both in Dr. Mohs Chemosurgery Clinic in Madison, Wisconsin or in the offices of physicians who had learned the technique firsthand from Dr. Mohs. In 1967 the American College of Chemosurgery was formed. It consisted primarily of dermatologists and had the first annual meeting. However, the use of chemo in the name Mohs chemosurgery was confusing to patients and physicians. As a result, the terms Mohs surgery and Mohs micrographic surgery (MMS) came into existence. By the 1970 s, several dermatology residency programs began to provide training in Mohs surgery. In the 1980 s, the American College of Chemosurgery launched formal post-residency fellowship in Mohs surgery, and in 1986 officially changed its name to the American College of Mohs Micrographic Surgery and in 1987, to the American College of Mohs Micrographic Surgery and Cutaneous Oncology (ACMMSCO) to reflect the predominance of the fresh tissue technique. The College also functions as a regulatory and certification body for the 60 fellowship 2 Dermatol Sinica, Mar 2008
Mohs surgery Fig. 1 Mohs Surgery procedure (by ACMMSCO). Dermatol Sinica, Mar 2008 3
Tsu-Yi Chuang Fig. 2 Schematic of Mohs Technique (by UCSF Department of Dermatology). 4 Dermatol Sinica, Mar 2008
Mohs surgery training programs (most in North America) and as a source of continuing education for more than 800 practitioners of MMS. The Mohs Fellowship Since the 1980 s, several training programs started to offer formal post-residency fellowships in Mohs surgery. The fellowship usually is a oneyear or two-year training. Scripps Clinic (California), University of Michigan, Mayo Clinic (Rochester, Minnesota), University of Wisconsin, Medical University of South Carolina, University of Texas MB, University of St. Louis, and others are some of the programs offered this training. Usually, cases for Mohs Surgery will be performed under the supervision of approved Mohs surgeons. Repairs will be done with specialties in addition to dermatology (e.g., plastic surgery, oculoplastic surgery, head and neck surgery, etc.). New patient and follow-up clinics exist as do consultant staff radiotherapy, maxillofacial prosthetics, oral surgery, hematology/ oncology, and others. Adequate training in anatomy will be provided via a fresh cadaver laboratory. The fellow will learn the operation of the Mohs laboratory and become proficient at preparing sections in both the fresh and fixed techniques. All sections will be reviewed with faculty Mohs surgeons who might not be certified pathologists, however. Therefore, dermatopathologist consultation is available at all times. Although trainees will have sufficient training in reading frozen section and permanent histopathological slides, the fellows will not be trained to meet the requirement as a certified dermatopathologist. The fellow may also participate in other aspects of dermatologic surgery. This will include, but is not limited to, hair transplants, dermabrasions, chemical peels, tumescent liposuction, scar revisions, sclerotherapy, cosmetic procedures, filler materials, podiatric procedures including nail surgery, particle resurfacing, electrosurgery and cutaneous laser surgery (including CO2 and/ or Erbium Laser skin resurfacing, plus other lasers, i.e. vascular, pigmented, hair removal, and other systems). The fellow will become proficient in the application of all types of bandages required for dermatologic surgery and Mohs Surgery. The training is going well beyond the original scope of Mohs surgery and covering cosmetic surgery, plastic surgery and laser surgery. It is apparent why the period of training went from a few days 30 years ago to 2 plus years now. But less than half of the Mohs surgeons had actually completed Mohs fellowship. According to a 2002 AAD Practice Survey, only 6.9 % of dermatologists had completed a Mohs fellowship, yet 16.9 % of dermatologists regularly do the Mohs surgery. Completion of the fellowship allows the fellow to qualify for membership in the ACMMSCO. Nonetheless, ACMMSCO is not formally recognized by the official medical specialty body, the American Board of Medical Specialties (ABMS), nor is the Mohs fellowship. In April, 2004, ACGME (Accreditation Council for Graduate Medical Education) approval of the Procedural Dermatology Fellowship was granted and became effective on July 1, 2004. This ABMS officially recognized fellowship will teach and train Mohs surgery technique in addition to dermatological surgery. But existing Mohs Fellowship Programs would not be automatically transformed or converted to Procedural Dermatology Fellowships. When these two programs would become one remains to be seen. At least it is unlikely in the foreseeable future. The Advantages of Mohs Surgery The Mohs surgery is said to be indicated for basal and squamous cell carcinoma (SCC) in the following conditions: Lesion is > 1cm on nose and >2cm elsewhere Lesion is on H-zone of face Lesion is an aggressive type: like sclerosing/ morpheaform Lesion is a recurrent Lesion is on irradiated skin Lesion is an ill-defined skin cancer Mohs surgeons often claim that Mohs technique has the following advantages and should be Dermatol Sinica, Mar 2008 5
Tsu-Yi Chuang the standard of care for all skin cancers including melanoma and Merkel cell carcinoma: 1. MMS has the highest cure rate for skin cancer, the recurrent rate of BCC is < 1%. 2. MMS is the most cost-effective management for skin cancer. 3. MMS can maximize the preservation of normal tissue. 4. MMS can remove melanoma in the most precise and complete way and thus should be the standard of care for melanoma. And the truth? THE MYTH AND THE TRUTH OF MOHS SURGERY 1. MMS has the highest cure rate for skin cancer: the recurrent rate is < 1%. Dr. Mohs documented the result from his consecutive series of 9,351 BCCs: a 5-year recurrent rate of 0.7%, the best ever recorded. 3, 4 His series has been by far the largest. But this superb outcome was from his original fixed-tissue technique which was later abandoned and replaced by fresh-tissue technique. The fresh-tissue technique, however, gave him a result of a 1.9% recurrent rate. 4 The second largest series was reported by Dr. Robins: 5 a 1.8% BCC recurrence after 3,218 primary BCCs excised. The third largest series of Mohs surgery, 1,886 primary BCC patients in total, was detailed by Leibovitch et al. 6 They described a 1.4% recurrent rate. In other words, the recurrence rate has never been under 1% based on several largest series of MMS. How were BCC recurrent rates by traditional surgical excision and other procedures? A 1990 report on 480 cases from the Rochester, Minnesota where Mayo Clinic located showed a recurrent rate of 4.8% in primary BCCs 4.5 years after traditional surgical excision. 7 A recent study from Netherlands demonstrated the recurrent rate of 408 primary BCCs was 3% by traditional surgical excision after a 5 year followup. 8 Comparing to 2% recurrent rate by MMS, there is no statistical significant difference between the two methods. 8 A procedure called electrodessication and curettage, mostly after shave excision, claimed a respectable recurrence rate of 4% by Barlow et al. 9 This has been a procedure commonly performed by dermatologists who tried to avoid the hassle of surgery. Even a time-honored cryosurgery (i.e., tissue was deep frozen by using liquid nitrogen or dry ice) could reach a respectable 5 year recurrent rate of 2.7% in 4,228 cutaneous carcinomas. 10 2. MMS is the most cost-effective. A BCC could be excised by traditional surgical excision with 60% less cost than by MMS. Use the removal of a 1-cm sized BCC on face as example: (this example and others as follows are presented in US dollars and based on current US medical insurance reimbursement policy) A surgical excision with a layer closure (i.e., dermal and adipose tissue were approximated by subcutaneous sutures) would cost $435. In such case, excision and closure were billed under separate procedure codes and reimbursed separately. A Mohs surgery which involves two horizontal slices (reimbursed as two procedures called Mohs I & Mohs II) plus a layer closure would cost $1,040, i.e., a 2.5 times more costly. If avoidance of a recurrence should be the prime goal of using MMS for all aggressive BCCs, it might need 20 times higher cost to just avoid ONE recurrence. A recent study estimated that it would cost $32,844 to prevent a recurrent BCC by MMS, and $9,094 to prevent a recurrence developed after a previously excised BCC. 11 However, such a recurrent BCC, if it did occur, could be easily handled with less than $1,500 price tag. Besides, in this study, only aggressive BCCs were included. Therefore, the chance of recurrence was high in this study. In other words, if lower-risk BCCs were put into the equation, less recurrence might happen. This would end up with an even 6 Dermatol Sinica, Mar 2008
Mohs surgery higher cost to prevent a rarer recurrence. Has MMS been used in less aggressive BCC/ SCC in a real world practice? It has. It was called over-utilized by Dr. Randall K. Roenigk at the Mayo Clinic. MMS has been performed 6 times more often in the past 12 years. The utilization rate of main Mohs surgery code 17304 increased from 80,000 in 1993 to 450,000 in 2005. In the same period, the rate of skin biopsy, a required procedure before MMS performed, just increased 2 times. It was obvious that MMS was over-utilized in less aggressive BCC/SCC or in in-situ or borderline malignancies. In general, most Mohs surgeons would perform an average of two slices for BCC/SCC. Performing 4 slices (i.e., Mohs I~IV, reimbursed as 4 separate procedures by using 4 unique procedure codes) and more (billed as Mohs X under yet another procedure code) is not unusual, however. The installment of new 2007 Mohs surgery codes (Table. 1) probably would not influence the way the Mohs surgeons behave. A noted Floridian dermatologist, a past-president of Floridian Mohs Surgery Society, has performed 4-level/slices for every lesion of his patients had for years until indicted by Florida State recently. Shamelessly, he had diagnosed EVERYONE walked into his office had skin cancer. MMS is hardly cost-effective. 3. MMS can maximize the preservation of normal tissue. It could be tough to maximize the preservation of normal tissue for any Mohs surgeon. It might be true that Mohs surgeons would remove the skin tissue until reach the level of clearance (i.e., obtain the slice of skin without cancer cells) and stop. But they still had to sacrifice additional normal tissue to overcome the odd size and shape Table. 1 2007 Mohs Surgery CPT Codes. Codes Description Reimbursement by Insurance (US dollars) 17311 1 st stage with up to 5 tissue blocks, $568~$609 face, head, neck, hand, feet and genitalia 17312 each additional stage after 1 st stage, $340~$367 with up to 5 tissue blocks if there are 3 additional stages performed, the reimbursement is $340~$367 X 3= $1020~$1101, plus $568~$609( for the 1 st stage), the total is $1588~$1710 17313 1 st stage with up to 5 tissue blocks, $518~$556 trunk and extremities 17314 each additional stage after 1 st stage, $315~$340 with up to 5 tissue blocks 17315 each additional tissue blocks after first 5 tissue blocks $68~$72 in any stage Dermatol Sinica, Mar 2008 7
Tsu-Yi Chuang of the wound created by MMS to obtain cleancut edges for best cosmetically acceptable result. Thus, the skin sacrificed under MMS technique and the subsequent repair/reconstruction is often the same as in traditional surgical excision, nit less. For melanoma in situ, they actually advocated removing more tissue for the sake of complete clearance, i.e., removing of all visible (by frozen section, of course) melanocytic cells. Mohs surgeon claimed that 0.5 cm margins for melanoma in situ or lentigo maligna is not adequate to eradicate the malignancy. They accentuated a need for a much wider margin, up to several cm. But for years, most surgeons (not Mohs surgeons) have successfully removed MIS with very conservative margins and still achieved a nearly 100% cure rate. Further, considering the fact that less than 5% recurrence rate of BCC was achieved by electrodessication and curettage. This is a procedure often called to have the most incomplete excision. If incomplete excision can obtain a decent result then a complete excision as done by MMS might take too much tissue out without justification. Maximize the preservation of normal tissue? Hardly. 4. MMS should be the standard of care for melanoma. The outcome, i.e., recurrence and metastasis, depended upon how wide the margins of excision being made. Good evidence from many randomized controlled studies pointed to the adequacy of a 1-cm margins for <1mm (thickness) melanoma, 2-cm margins for 1-4mm melanoma and 3-cm margins for more aggressive melanoma. The measurement of the margins was based on visible lesion margins, not on histopathological tissue margins or margins marked out by frozen sections. There is no evidence, either from randomized controlled studies or long-term cohort follow-up studies, to support that MMS with its precise and complete way in removing melanoma resulted in less frequent recurrence and metastasis with or without 1~3 cm margins. Even the claim of removing melanoma in the most precise and complete way met with serious challenge. It is difficult to delineate the margins of melanoma on frozen sections for Mohs surgeons to begin with. Pathologists already pointed out that the frozen-section of pigmented lesions cannot accurately delineate the atypical melanocytic hyperplasia from melanoma in situ nor melanocytes from keratinocytes. Furthermore, the failure rate in identifying a lentiginous spread of melanoma on frozen section may approach 50%. 12 The diagnostic discrepancy rate between experienced dermatopathologists was 40% between frozen and permanent section. 12 Pathologists thus advocated that frozen sections should have no role in the evaluation of melanoma. In another report, a sensitivity of 59% and specificity of 81% in 50 of 154 frozen sections were observed. 13 And thus, frozen sections alone were called unreliable for evaluating the margins while excising melanoma in situ. 13 Such problems were recognized by well-trained and experienced pathologists. 12, 13 But Mohs-technique-advocators with less skilled in pathology astonishingly believed they could count on frozen sections to remove melanoma precisely and completely. Further, without board-certification in pathology, they might have got themselves into legal problem if there were a lawsuit disputing the appropriateness of MMS in treating melanoma. CONCLUSION Mohs surgery has been a brilliant invention by Dr. Mohs. It did help to clear BCC/SCC in an efficient way at certain difficult anatomic sites like H-zone of the face. It could clear aggressive and ill-defined BCC/SCC with precision. But we have to admit that this technique was abused. It was used to cover areas well beyond Dr. Mohs originally intended to: small and less aggressive skin cancers, skin cancers on trunk and extremities, melanoma, Merkel cell carcinoma and other skin cancers, etc. The Mohs fellowship and its 8 Dermatol Sinica, Mar 2008
Mohs surgery training are expanded to cover the territories not originally designated to: laser surgery, cosmetic treatment, liposuction, hair transplant, etc. Its benefits and advantages were overly exaggerated. We should go back and see what Mohs surgery is all about: It is a technique with its intended goal and specific target. REFERENCES 1. Mohs FE: Chemosurgery. A microscopically controlled method of cancer excision. Arch Surg; 44: 279-295, 1941. 2. Tromovitch TA, Stegeman SJ: Microscopically controlled excision of skin tumors. Arch Dermatol 110: 231-232, 1974. 3. Mohs FE. Chemosugery: microscopically controlled surgery for skin cancer-past, present and future. J Dermatol Surg Oncol 4: 41-54, 1978. 4. Mohs FE: Chemosugery: microscopically controlled excision of cutaneous cancer. Head Neck Surg 1: 150-163, 1978 5. Robins P. Chemosurgery: My 15 years of experience. J Dermatol Surg Oncol 7: 779-789, 1981. 6. Leibovitch I, Huilgol SC, Selva D, et al.: Basal cell carcinoma treated with Mohs surgery in Australia II. Outcome at 5-year follow-up. J Am Acad Dermatol 53: 452-457, 2005. 7. Chuang TY, Popescu A, Su WP, et al.: Basal cell carcinoma. A population-based incidence study in Rochester, Minnesota. J Am Acad Dermatol 22: 413-417, 1990. 8. Smeets NW, Krekels GA, Ostertag JU, et al.: Surgical excision vs. Mohs micrographic surgery for basal-cell carcinoma of the face: randomised controlled trial. Lancet 364: 1766-1772, 2004. 9. Barlow JO, Zalla MJ, Kyle A, et al.: Treatment of basal cell carcinoma with curettage alone. J Am Acad Dermatol 54: 1039-1045, 2006. 10. Zacarian SA: Cryosurgery of cutaneous carcinomas. An 18-year study of 3,022 patients with 4,228 carcinomas. J Am Acad Dermatol 9: 947-956, 1983. 11. Essers BA, Dirksen CD, Nieman FH, et al.: Cost-effectiveness of Mohs Micrographic Surgery vs. Surgical Excision for Basal Cell Carcinoma of the Face. Arch Dermatol 142:187-194, 2006. 12. Smith-Zagone MJ, Schwartz MR: Frozen section of skin specimens. Arch Pathol Lab Med 129: 1536-1543, 2005. 13. Barlow RJ, White CR, Swanson NA: Mohs micrographic surgery using frozen sections alone may be unsuitable for detecting single atypical melanocytes at the margins of melanoma in situ. Br J Dermatol 146: 290-294, 2002. Dermatol Sinica, Mar 2008 9