Treatment of advanced squamous cell carcinoma of the skin with isotretinoin.

STUDY OBJECTIVE

To determine the efficacy of oral isotretinoin in refractory advanced squamous cell carcinoma of the skin.

DESIGN

Case series trial.

SETTING

Tertiary care center at a university hospital.

PATIENTS

A consecutive collection of four patients with advanced squamous cell carcinoma of the skin who failed to respond to standard surgical or radiation therapy.

INTERVENTIONS

Isotretinoin in gelatin capsules was given at a total daily dose of 1 mg/kg body weight in two divided doses for at least 4 weeks.

MEASUREMENTS AND MAIN RESULTS

Bidimensional tumor measurements at monthly intervals showed striking responses to isotretinoin in all four patients. Response durations ranged from 2 to more than 23 months. The drug produced reversible moderate mucocutaneous side effects and asymptomatic laboratory abnormalities.

CONCLUSIONS

Impressive responses to isotretinoin occurred in our four patients and in six of ten other reported patients. Retinoic acid's mechanisms of action in cutaneous squamous cell carcinoma is not precisely known, but may involve the modulation of epidermal growth factor receptors and certain protein kinases. These in-vitro findings and the clinical data suggest that retinoids may be an effective and well-tolerated therapy for refractory advanced squamous cell carcinoma of the skin. The absence of any other effective systemic therapy indicates the need for continuing trials with retinoids in this disease.