Cancer of the Lip

Introduction

The lip is the most common site of origin for squamous cell carcinoma of the oral cavity. Unlike other cancers of the oral cavity, the etiology and clinical outcomes of squamous cell carcinoma more closely resemble squamous cell carcinoma of the skin. Cancer of the lips accounts for 0.6% of all malignancies diagnosed in the United States. The primary risk factor for cancer of the lip is sun exposure. As with other skin malignancies, fair skin complexion increases the risk for lip cancer. A study of Canadian farmers showed that these sun-exposed workers had a threefold increased risk of cancer of the lip compared with people with indoor occupations after controlling for smoking history. Also implicating the powerful role of sun exposure in development of cancer of the lip is the finding that cancer of the lip is 40 times more prevalent on the external than the inner lip.

The risk of cancer of the lip increases with age; the average age at diagnosis is in the sixth decade of life. The lower lip is 12 times more likely to be affected than the upper lip, as it sustains greater exposure to sunlight. Of all cancers of the lip, squamous cell carcinoma represents the vast majority. A large epidemiological analysis revealed that up to 95% of nonmelanoma cancers of the lower lip are squamous cell carcinoma. Basal cell carcinoma, the second most common nonmelanoma cancer of the lip, is more likely to be found on the external upper lip and in females. Other types of cancer occur less commonly on the lip, including malignant melanoma and malignant tumors of minor salivary gland origin, such as adenoid cystic carcinoma and adenocarcinoma.

The role of human papillomavirus in the development of squamous cell carcinoma of the head and neck continues to be clarified, but no evidence has been found to date that implicates this virus as a cause of lip cancer. Immunosuppressed populations are at significantly increased risk for lip cancer. Patients who have undergone kidney transplant have a 30-fold increased risk on account of immunosuppressive antirejection drug regimens. The degree of immunosuppression appears to be important, as patients on higher doses demonstrate a higher risk of skin cancer than patients on low-dose regimens. Patients with HIV infection also have a greater risk for development of lip cancer.

Patients with lip cancers generally present at an early stage, as the location is a cosmetically obvious area. Tumors less than 2 cm in size (T1 stage) account for 75% to 80% of lip cancer diagnoses. The staging guidelines for cancer of the lip follow the guidelines for cancer of the oral cavity. These patients generally do well, and surgical excision is curative. In the current literature, the reported 5-year survival rates in patients with squamous cell cancer of the lip without lymph node metastases are between 85% and 99%. A small number of patients present with more advanced primary cancers, characterized by invasion into deeper structures.

While patients with cancer of the lip without cervical metastasis can expect excellent rates of survival, the prognosis is guarded for patients who have lymph node metastasis; the survival rate for these patients decreases to 25% to 50%. Therefore, identification and management of occult neck metastasis are critical. A number of prognostic factors for lymph node metastasis for squamous cell carcinoma of the lip have previously been reported: tumor size/T-stage, tumor grade, depth of invasion, perineural invasion, extreme mitotic activity, positive surgical margins, commissure involvement, and local recurrence.

Management of the N0 neck is controversial; the recent literature has suggested that “high-risk” patients should receive consideration for management of the regional lymphatic basin. Sentinel lymph node biopsy is a surgical option already widely applied as a tool to assess the at-risk lymph node basin in skin cancer. Its role in treatment of squamous cell carcinoma of the oral cavity is also gaining acceptance. This option is especially attractive in lip cancer, as the primary tumor is readily accessible for injection of radioisotope and small neck incisions minimize interference with reconstructive options for the lip.

A chapter on cancer of the lip is incomplete without addressing reconstructive techniques. Reconstruction of defects of the lip can be complex, especially when resection involves the vermillion border or oral commissure. Reconstructive techniques are used to minimize microstomia, retain oral competence, and optimize the cosmetic result. While reconstruction of the lip can be complex, there are several basic principles to guide the surgeon toward the appropriate technique.

• Defects amounting to one-half of the lip can and should be closed primarily.

• Meticulous reapproximation of the vermillion border should be achieved.

• If greater than one-half of the lip is resected, consideration should be given to advancement flaps or “lip-switch” procedures (described later).

• If resection involves the oral commissure, the Estlander flap can be used.

• For larger resections (greater than two-thirds), local tissue rearrangement is possible with the Karapandzic flap; however, consideration should be also given to free tissue transfer techniques.

Surgical technique is described as follows for the aforementioned types of lip reconstruction.

Key Operative Learning Points

• 1.

  Discuss ablative techniques for removal of cancer of the lip with consideration of optimal reconstruction.

• 2.

  Understand the reconstructive ladder and how it may be used in reconstruction of the lip.

• 3.

  For full-thickness reconstruction of the lip involving greater than two-thirds of the lip, consideration of the use of free tissue transfer should also be given.

Preoperative Period

Operative Period