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Adjuvant Therapy for High-Risk Squamous Cell Carcinomas

Retinoids and interferon-alfa failed to provide benefit to patients with aggressive SCCs.

The great majority of squamous cell carcinomas (SCCs) are effectively treated with surgery. However, some SCCs seem to have a high risk for local recurrence and metastatic disease. Investigators evaluated the usefulness of adjuvant 13-cis-retinoic acid and interferon-alfa for high-risk SCCs (defined as having size 2 cm; perineural invasion; deep invasion into muscle, bone, or cartilage; clinical fixation to deeper structures; or presence of regional metastasis). After surgical resection, with or without radiation therapy, 66 patients were randomized to receive a 60-month course of 13-cis-retinoic acid (1 mg/kg/day) plus 1 million units of interferon-alfa three times per week or to serve as controls without adjuvant therapy. Patients were followed for 18 months after conclusion of treatment, or to the point when either a new skin cancer developed or the tumor locally recurred or metastasized. These patients came from a tertiary cancer referral center, and it took 6 years to accumulate 66 patients.

One patient withdrew immediately, and 65 patients with a total of 71 SCCs were included in the intent-to-treat analysis. Tumor recurrence, including metastatic disease, occurred in 29% of the adjuvant treatment group and 26% of the control group. New SCCs developed in 16% of the adjuvant treatment patients and 18% of controls. None of these changes were statistically significant. Recurrences and new SCCs were significantly more frequent in patients who had surgery plus radiation therapy (49%) than in those who had surgery alone (19%). Seven patients discontinued the study early, including the one who dropped out before start of treatment, three who were lost to follow-up, two who died of unrelated causes, and one who dropped out due to treatment-related side effects. These effects included skin dryness, cheilitis, conjunctivitis, and flu-like symptoms, and necessitated dosage reduction in 29% of patients.

Comment: Unfortunately, adjuvant therapy with retinoids and interferon-alfa provided no benefit to patients with high-risk squamous cell carcinomas while subjecting them to significant morbidity from side effects. Fortunately, these types of aggressive SCC are quite rare. Early surgical intervention with careful margin examination remains the best hope for a cure. The higher rate of tumor recurrence in patients who underwent radiation therapy probably reflects that radiation was chosen for the largest and most aggressive tumors.

— George J. Hruza, MD

Published in Journal Watch Dermatology May 25, 2007

Citation(s):

Brewster AM et al. Randomized trial of adjuvant 13-cis-retinoic acid and interferon alfa for patients with aggressive skin squamous cell carcinoma. J Clin Oncol 2007 May 20; 25:1974-8.

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