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Excision
Excision
Surgical excision is a mainstay of treatment for NMSC due to both the potential for rapid healing and the ability to examine tissue histologically to ensure complete tumor removal. Although EDC or cryosurgery may be appropriate for treatment of some NMSC, surgical excision has both a higher cure rate and improved cosmesis over those options. Still, unlike MMS, where 100% of the margin is examined histologically, standard pathological review of a surgical excision specimen examines only a portion of the tumor margin. Tumors that are well defined are ideal for surgical excision, as the surgeon can assess clinical margins and confidently remove all of the tumor based on visual appearance alone.
Surgical technique for excision varies, though most lesions are excised with a fusiform ellipse with the long axis oriented along the relaxed skin tension lines. The length-to-width ratio of the ellipse should measure between 3:1 and 4:1 and the angles at the edges of the ellipse should be approximately 30 degrees to mitigate the risk of dog-ear formation. After the lesion is excised, the skin is undermined and a layered closure is performed. See Chapter 18 for a detailed discussion of linear closure approaches.
The goal of surgical excision is to completely remove the tumor while minimizing the removal and destruction of normal skin. Typically, surgical excision of NMSC requires that a margin of healthy skin surrounding the tumor be removed due to the risk of subclinical tumor extension.30 When performing surgical excision for NMSC, obtaining adequate surgical margins reduces the risk of positive histologic margins and the subsequent need for re-excision.31 In areas where there is limited excess skin and tissue preservation is vital, the limitations of excisional surgery must be recognized. In some circumstances, taking smaller surgical margins or referring for MMS may be more appropriate than simple surgical excision.
There are very few well-designed, qualitative, prospective studies examining appropriate surgical margins for NMSC. While some advocate a 4-mm margin,32 there is little evidence to support this, and individual practice varies.
BCC margins Features of the BCC that must be considered before determining surgical margins are how well defined the tumor is, tumor diameter and histologic subtype, anatomic location, and any prior treatments the patient has undergone.33 Ill-defined tumors may be poor excisional candidates because an accurate assessment of the clinical margin is often not possible. It may be difficult to determine the degree of subclinical spread for larger tumors, and such lesions may be more appropriately treated with MMS. Although 4-mm margins are generally more than adequate for BCC, some circumstances require larger margins, and some tumors have very extensive subclinical spread.32 Larger and recurrent tumors may require a larger margin of up to 10 mm.33 Very aggressive
histologic subtypes of BCC (morpheaform and sclerosing) are not appropriate for surgical excision because of their tendency to demonstrate aggressive subclinical spread. Facial lesions and recurrent lesions anywhere on the body are generally considered high risk and thus may be more appropriate for MMS.
SCC margins As with BCC, increased size, more invasive histological subtypes, and higher-risk anatomic locations are less conducive to surgical excision. One additional parameter that should be considered is vertical depth of invasion.33 As SCC invades deeper within the tissue, the surgical margins needed to clear the tumor also increase. It is generally accepted that a 4-mm margin is adequate when excising a low-risk SCC, while a 6-mm margin is adequate for higher-risk SCC.34 These numbers are based on a study that progressively excised 1-mm margins until cure was achieved, and found that 95% of low-risk SCC were cured at a 4-mm margin and 95% of high-risk SCC were cured at 6 mm.35 Others have argued that these margins may not be appropriate, and have suggested margins anywhere between 2 and 15 mm.33
In general, surgical excision has a very high cure rate for NMSC. Most tumors are adequately excised, but because there is no immediate histologic confirmation of negative margins, there is a risk for incomplete excision. One study showed that the cumulative 5-year recurrence risk with excision was 4.8% for BCC.36 When stratified, the risk was lower on the trunk, neck, and extremities, and slightly higher for excisions taking place on the head, with recurrence rates being highest for larger (>10 mm) lesions on the head. Studies evaluating cure rate of surgical excision of SCC suggest recurrence rates of 8% and 23% for primary and recurrent SCC, respectively.37 The clinician must decide whether wide local excision or MMS is most appropriate in the setting of tumor recurrence or incomplete excision, especially as data regarding BCC demonstrated that recurrent tumors treated with MMS have a 5.4% recurrence rate compared to a 17.4% recurrence rate when treated with re-excision.37 Still, given their sometimes indolent nature and propensity to affect the elderly, it is important to consider either approach, as well as watchful waiting, when deciding on management strategies for recurrent BCC in elderly patients. When considering recurrent SCC, MMS has similarly improved outcomes over standard re-excision.
Although guidelines for excision of NMSC have been set forth by the National Comprehensive Cancer Network, better-defined recommendations that take into account important tumor and patient characteristics need to be established. It is important to take into account the patientโs history, tumor history and histology, anatomic location, and tumor size in order to achieve optimal outcomes for surgical excision of NMSC.