Patients and Methods: In a prospective randomized study, 311 melanoma patients with a Breslow thickness greater than or equal to 1.5 mm were assigned to either adjuvant IFN alpha 2a treatment (n = 154) or observation (n = 157) after excision of the primary tumor. IFN alpha 2a was given daily at a dose of 3 mIU subcutaneously (SC) for 3 weeks (induction phase), after which a dose of 3 mIU SC three times per week was given over 1 year (maintenance phase).

Results: Prolonged disease-free survival was observed in patients treated with IFN alpha 2a versus those who underwent surgery alone. This difference was significant (P = .02) for all patients enrolled onto the study (intention-to-treat analysis) at a mean observation time of 41 months. Subgroup analysis showed that Breslow tumor thickness had no influence on treatment results in the groups of patients investigated.

Conclusion: Adjuvant IFN alpha 2a treatment diminishes the occurrence of metastases and thus prolongs disease free survival in resected primary stage II cutaneous melanoma patients. (C) 1998 by American Society of Clinical Oncology.