Traditional Treatment of Non-Melanoma Skin Cancer
Patients with skin cancer are often managed by head and neck surgeons, Mohs surgeons, or plastic and reconstructive surgeons. Ideally, these disciplines should work collaboratively to provide the patient with optimum cancer management. Unfortunately, this is not always the reality. Standard treatment for aggressive non-melanoma skin cancer is surgical excision with histologically negative margins. The overarching surgical principle is complete surgical resection with tumor-free margins as determined by careful pathologic review of the margins, either by frozen section or delayed review of fixed tissue sections.
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July 2007The conventional surgical approach is en bloc resection. The surgeon is guided by tactile and visual cues and high resolution imaging to estimate the volume of tumor and the surrounding tissue necessary for complete resection. This approach is analogous to en bloc resection of an upper aerodigestive tract squamous cell carcinoma, and similar principles apply. Take, for example, an invasive squamous cell carcinoma of the lateral oral tongue. The tried-and-true therapeutic approach is partial glossectomy with a generous margin of surrounding normal mucosa and muscle. With the knowledge of the propensity for these tumors to exhibit perineural spread, tracking along muscle bundles and displaying lymphovascular invasion, few would advocated a conservative excision with maximum preservation of the adjacent tongue.
Studies have shown that wide resection with tumor-free margins provides the patient with the best opportunity for local control. Why, then, should we consider cutaneous squamous cell carcinoma to be inherently different from an oral tongue cancer? Their clinical and biologic behavior is not dissimilar. The extent of resection of normal tissue margin should be determined by the biologic behavior of the primary tumor. Squamous cell carcinomas of the skin are inherently different from basal cell carcinomas in the proclivity of the former to infiltrate deeply, exhibit lymphovascular invasion, and propagate along motor and sensory nerves. For cutaneous squamous cell carcinomas, failure of the surgeon to recognize their biologic behavior and aggressively resect the tumor with generous margins will significantly increase the patient’s risk for recurrence.
Differences in Approach
Significant philosophical differences exist in the surgical management. The head and neck surgeon resects aggressive cutaneous squamous cell carcinoma in an en bloc fashion with wide margins. In contrast, the Mohs surgeon may take a fundamentally different approach. While complete surgical resection with histologically clear margins is the goal of Mohs surgery, tissue conservation is a stated priority. The head and neck surgeon relies on the surgical pathologist to microscopically assess the margin status. The Mohs surgeon serves as both the pathologist and surgeon, and advocates this approach because of the precise nature it affords for tumor mapping, the ability to immediately assess the margins, and conservation of normal adjacent tissue. The Mohs surgeon advocates immediate reconstruction, given the confidence that the margins are free of tumor. However, the assessment of the margins and the presence of perineural invasion on frozen section are, at times, difficult even for an experienced dermatopathologist who has training in surgical pathology and has completed a subspecialty fellowship. Studies have demonstrated the variability among experienced pathologists when interpreting frozen sections following excision of cutaneous neoplasms.