Therapeutic Strategies

The progressive nature of SC emphasizes the need for (1) prevention, (2) early diagnosis, (3) effective therapeutic intervention, and (4) close long-term follow-up. Measures to reduce UVR exposure and the consistent use of a sunscreen may occasionally result in spontaneous resolution of SC.^15,66 Available therapeutic options include the application of topical chemicals and the use of ablative or surgical methods.^36,69 Importantly, clinicians must avoid treating SC on the basis of clinical findings alone.

When SC presents as a well-circumscribed nodule or papule < 5 mm in diameter it is amenable to an excisional biopsy.³⁶ Serial sections of the surgical specimen must be prepared and evaluated histologically. Alternatively, Mohs micrographic surgery (MMS), because of its excellent cosmetic yield, may be considered. If the histologic diagnosis confirms mild to moderate dysplasia no further treatment is indicated, but the patient should be placed in a closely monitored follow-up program.

When the nodules, papules, areas of atrophy, erosions or prolonged ulcerations are > 5 mm in diameter, an incisional biopsy is indicated.³⁶ Serial sections of the specimen must be evaluated histologically. If the histologic diagnosis is mild to moderate dysplasia the area may be treated with 5% topical 5-fluorouracil or imiquimod. Despite excellent clinical remission of SC, neither of these two drugs has been shown to completely eradicate dysplasia at the microscopic level.³⁶

Alternatively, ablation with cryotherapy (liquid nitrogen applied with a cryoprobe) or electrosurgery can be useful for the treatment of focal SC. Cryotherapy requires no local anesthesia and five-year cure rates as high as 99% have been reported.³⁶ Electrosurgery requires local anesthesia and may lead to damage to adjacent tissues and scar formation. A major disadvantage of both of these techniques is that they do not yield specimens for histologic evaluation of serial sections.

SC characterized by diffuse leukoplakia or atrophy of the lip vermilion should have a single incisional biopsy of the most suspicious area, which has generally been shown to correspond to a greater degree of dysplasia. If the histologic diagnosis is mild to moderate dysplasia, field therapy with 5% topical 5-fluorouracil or imiquimod may be an option. However, CO2 laser ablation has been shown to more predictably resolve both the clinical and histological manifestations of SC.³⁶

SC with severe dysplasia is considered equivalent to or indistinguishable from SCIS and any patient with a lip lesion suspected to be malignant should be referred to an oral and maxillofacial or head & neck surgeon for further assessment. The clinical behavior of SCC of the lip falls between cutaneous SCC and intraoral mucosal SCC.⁷⁰ Cutaneous SSC is highly curable (95%), while the 5-year survival rate for oral cavity and pharynx SCC is 66.9%. The 5-year survival rate for SCC of the lip is 90.9%.²¹ Initial tumor size directly influences the risk of nodal metastasis. The risk for nodal metastasis for T1 tumors is 3.4% - 7%, for T2 tumors 11% - 35%,and for T3 and T4 tumors 17% - 100%.⁷⁰ The most commonly involved nodes are the submandibular, followed by the submental, jugular chain, and the intraparotid groups.⁵⁸

Surgical excision is the most prudent and effective approach to the treatment of diffuse SC, as it allows for the physical removal of part or all of the lip vermilion.³⁶ The most common surgical technique is vermilionectomy or lip-shave. Unlike CO2 ablation, it has the advantage of providing specimens for histologic evaluation of serial sections. The advantage of CO2 laser ablation when compared to scalpel vermilionectomy is that it results in fewer esthetic side effects.

When scalpel vermilionectomy is performed, the orbicularis oris muscle is conserved and closure is obtained by advancing and suturing the labial mucosa to the skin to create a new lip line. The technique can also be combined with a wedge procedure to simultaneously eliminate SCIS or a small SCC. Side effects are common and may include the presence of hairs near the newly established lip line, paresthesia, and scarring, which may result in restriction of labial motion.³⁶