Some citations in the text of this section are followed by a level of evidence. The PDQ editorial boards use a formal ranking system to help the reader judge the strength of evidence linked to the reported results of a therapeutic strategy. (Refer to the PDQ summary on Levels of Evidence for more information.)
Localized squamous cell carcinoma (SCC) of the skin is a highly curable disease. There are a variety of treatment approaches to localized SCC, including excision, radiation therapy, cryosurgery, and electrodesiccation and curettage. Mohs micrographic surgery is a form of tumor excision that involves progressive radial sectioning and real-time examination of the resection margins until adequate uninvolved margins have been achieved, avoiding wider margins than needed.
There is little or no good-quality evidence that allows direct comparison of outcomes for patients with sporadic, clinically localized SCCs treated with local therapies. A systematic literature review found only one randomized controlled trial in the management of such patients, and that trial compared adjuvant therapy to observation after initial local therapy rather than different local therapies. In that small single-center trial, 66 patients with high-risk, clinically localized SCC were assigned randomly, after surgical excision of the primary tumor (with or without radiation, depending on clinical judgment), to receive either combined 13-cis-retinoic acid (1 mg/kg orally per day) plus interferon-alpha (3 � 106 U subcutaneously 3 times/week) for 6 months or to observation. In the 65 evaluable patients after a median follow-up of 21.5 months, there was no difference in the combined (primary) endpoint of SCC recurrence or second primary tumor (45% vs. 38%; hazard ratio = 1.13; 95% confidence interval [CI], 0.53-2.41), nor in either of the individual components of the primary endpoint.[Level of evidence 1iiDii]
Absent high-quality evidence from controlled clinical trials, the management of clinically localized cutaneous SCC is based upon case series and consensus statements from experts. The commonly used treatments are listed below.
Excision is probably the most common therapy for SCC. This traditional surgical treatment usually relies on surgical margins ranging from 4 mm to 10 mm, depending on the diameter of the tumor and degree of differentiation. In a prospective case series of 141 SCCs, a 4-mm margin was adequate to encompass all subclinical microscopic tumor extension in more than 95% of well-differentiated tumors up to 19 mm in diameter. Wider margins of 6 mm to 10 mm were needed for larger or less-differentiated tumors or tumors in high-risk locations (e.g., scalp, ears, eyelids, nose, and lips). Re-excision may be required if the surgical margin is found to be inadequate on permanent sectioning.