Basal cell carcinoma (BCC) is the most common nonmelanoma skin cancer. The malignant character of the tumor depends on the destructive growth of the primary tumor rather than on metastasis. Patients who have been treated for BCC have a higher risk of developing another BCC. Substantial disfigurement can occur if the BCC is located on the face. Although most BCCs can be cured using standard office surgical procedures, some require more extensive therapy, especially those that recur. Thissen and associates systematically reviewed the literature to determine the recurrence rates of BCCs after various therapies.
The authors reviewed studies that reported recurrence rates after the following types of surgery: excision, Mohs surgery, cryotherapy, curettage and electrodesiccation, radiation, immunotherapy and photodynamic therapy. Of 298 studies, only 18 were acceptable as prospective studies of primary BCC with a follow-up of more than five years. The 18 series included reports on the treatment of 9,930 primary BCCs. The main outcome measures were the recurrence rates after different therapies for BCCs, resulting in the development of guidelines for the treatment of these disorders.
Results of this systematic review demonstrated that BCCs treated with Mohs micrographic surgery had the lowest recurrence rates after five years, followed in order by those treated with surgical excision, cryosurgery, and curettage and electrodesiccation. The authors were unable to identify a recurrence rate for specific therapies because of the lack of uniformity in the methodology of each study.
The review demonstrated that the risk for recurrence of a specific BCC depends not only on the treatment modality but also the location, size and histologic subtype of the tumor, and the age, immune status and sex of the patient. Tumors located around the ear are known to have a higher risk for recurrence. Mohs surgery appears to be the treatment modality with the lowest recurrence rate, even for BCCs localized in anatomic sites at high risk for recurrence. Tumors that are smaller (i.e., less than 2 cm) can be successfully treated with primary surgical excision. The analysis of the literature indicates that the recurrence rates with cryotherapy and electrodesiccation are higher than those occurring with surgical methods, even simple excision. It was possible to assess only one study using radiotherapy, but it appears that use of this modality resulted in less favorable cosmetic results more than five years after therapy. The long-term cure rate after immunotherapy is not significant.
The authors conclude that if surgery is not contraindicated in the patient with BCCs of the nodular and superficial type, surgical excision remains the treatment modality of first choice. For larger BCCs in high-risk areas of the face (lateral canthus, orbital rim and brow, ear and nose) and head, and those with more aggressive growth patterns, Mohs surgery is recommended. If surgery is contraindicated, other modalities such as cryotherapy may provide adequate results.
editor's note: In an accompanying editorial, McGovern and Leffell make several important points. Treated recurrent BCCs have a significantly higher five-year recurrence rate than treated primary tumors. Inadequate treatment may play a role in converting a relatively benign cutaneous lesion into a more biologically aggressive, invasive and destructive tumor that is difficult to eradicate. If recurrence rates were the only determinant for choosing a treatment modality, Mohs surgery would be the choice for every BCC. Recurrence rates must be balanced by other factors, such as cosmesis, cost and histologic tumor characteristics. It should be stressed that most primary BCCs can be appropriately treated with non-Mohs surgical approaches.—b.a.