Although the Mohs technique is appropriate for most patients with basal cell carcinomas and nonaggressive squamous cell carcinomas, it does not take into account the biology and mechanisms of spread demonstrated by these aggressive tumors. Rather than an en bloc resection, the Mohs surgeon estimates the tumor extent by initially using a curette to remove all gross tumor. Next, the tumor is resected in levels with careful geometric orientation and mapping of the margins. Each excision is referred to as a level, and multiple levels may be required for complete tumor extirpation. Though very precise and consistent with a philosophy of maximum conservation of normal tissue, distance from the leading edge of the invasive tumor and the surrounding normal tissue may only be a few millimeters or less. This defies the biologic behavior of these aggressive cancers. For instance, the Mohs surgeon may accurately identify perineural invasion, but with a tissue conservation approach may not completely encompass the skip metastasis present in the involved nerve.
Explore this issue:July 2007
Analogous to the surgical management of oral tongue cancer, aggressive squamous cell carcinomas of the skin require careful treatment planning with preoperative imaging and multidisciplinary assessment by a radiation oncologist and, at times, the reconstructive surgeon. Determining the extent of the tumor facilitates complete resection. Pretreatment assessment by the radiation oncologist and reconstructive surgeon allows comprehensive planning for the appropriate use of radiation therapy and a method of reconstruction that will withstand the rigors of postoperative radiotherapy and restore the patient’s form and function.
Presurgical planning is particularly important for periauricular tumors that invade the parotid fascia. With the Mohs technique the facial nerve trunk and branches are approached directly within the depths of the wound and are at greater risk for injury. The more traditional en bloc resection dictates identification of the main trunk of the facial nerve and serial dissection of each branch. The nerve is preserved, provided that a plane of dissection exists between the tumor and the nerve. When encased by tumor, the nerve is resected. En bloc parotidectomy and wide excision provide a safe deep margin while maintaining the integrity of the facial nerve whenever possible.
Multidisciplinary Management Necessary
A multidisciplinary and comprehensive management philosophy will optimize care for these patients. Patients with aggressive cutaneous squamous cell carcinoma frequently require radiation therapy as an adjunct to surgical resection when the margins are either close or microscopically involved, nerve invasion is present, or lymph node metastasis occurs. In addition, the dental oncologist should assess the patient for the need for extractions or dental restorations if radiation therapy is indicated. Our philosophy is also to engage the reconstructive surgeon as a member of the team, so that the oncologic surgeon can resect the tumor unencumbered by the need to perform a reconstruction. The reconstructive surgeon can repair the defect with the confidence that oncologically free margins are obtained and the tumor has been adequately removed. This multidisciplinary approach affords the patient with the optimum opportunity for disease control and for functional and cosmetic restoration.