Background/aims Survival after diagnosis of metastasis from uveal melanoma is poor. Identifying individuals at high risk for metastasis and developing adjuvant therapy to prevent clinically apparent metastasis could improve survival. We conducted an adjuvant trial of sequential, low-dose dacarbazine (DTIC) and interferon-alpha-2b (IFN-α−2b) in patients with cytogenetic high-risk uveal melanoma.

Methods Patients diagnosed with iris, ciliary body or choroidal melanoma with high-risk tumour cytogenetics (monosomy 3) were offered adjuvant treatment with low-dose DTIC and IFN-α−2b following primary therapy. Eligible but not enrolled patients were observed for comparison. DTIC was administered at 850 mg/m² intravenously on days 1 and 28. IFN-α−2b was administered at 3 million units three times a week subcutaneously for 24 weeks beginning at week 9. Hepatic imaging was performed prior to adjuvant therapy and then at least every 6 months. Survival data were collected for 5 years after enrolment.

Results 33 patients (22%) were enrolled (treatment group), 29 (19%) were eligible but did not enrol (observation group) and 88 (59%) were not eligible. The 5-year metastasis-free survival (MFS) was 64%±9% for treated and 33%±10% for observed patients (p=0.05). The 5-year overall survival (OS) rate was 66%±9% for treated and 37%±10% for observed patients (p=0.02).

Conclusions When adjusted for differences in age, tumour size and initial treatment, survival between treated and observed patients was no longer significant (p=0.56 MFS and p=0.92 OS). Differences in baseline tumour characteristics between treated and observed patients can influence interpretation of results.

Trial registration number NCT01100528.