Modelling the cost-effectiveness of sentinel lymph node mapping and adjuvant interferon treatment for stage II melanoma.

Clinical studies have demonstrated that high dose adjuvant interferon therapy improves disease-free and overall survival among high risk (stage IIb and III) melanoma patients. Sentinel lymph node mapping (SLM) has been shown to accurately detect micrometastasis and may be used to identify higher risk stage II patients, who might benefit most from adjuvant interferon therapy. We modelled the cost-effectiveness of first testing with SLM and then treating with adjuvant interferon (IFN) therapy for stage II melanoma. We used a decision analytical model to compare four strategies for stage II patients after surgical excision of their melanoma: (1) treat all with low dose IFN; (2) test first with SLM and then treat only those with positive micrometastasis with high dose IFN; (3) test first with SLM and treat positives with high dose IFN and negatives with low dose IFN (test and treat appropriately); and (4) surgery only. Treatment, toxicity, follow-up and relapse costs were included over a 5 year time period. The primary outcome was cost per quality-adjusted relapse-free life year saved. Our analysis shows that, compared with the current surgery-only strategy, all three treatment strategies provide incremental benefits. The test and treat appropriately strategy is the most effective, with an incremental improvement of 0.64 quality-adjusted life-years (QALY). The cost-effectiveness of test and treat some with high dose IFN compared with the surgery-only strategy is $18,700/QALY. The test and treat appropriately strategy is also cost-effective compared with test and treat some at $31,100/QALY. In conclusion appropriate dosing of IFN therapy based on the results of SLM is a cost-effective strategy for stage II melanoma patients.