Clinical and economic issues in adjuvant chemotherapy for HER-2 positive breast cancer

Abstract

PURPOSE. To examine efficacy figures and drug expenditure for adjuvant chemotherapy in human epidermal growth factor receptor 2 (HER-2) positive breast cancer, in the Brazilian supplemental health insurance market. METHODS. We obtained efficacy data (disease free survival at 3-years) and drug cost estimate for current adjuvant strategies in HER-2 positive breast cancer: Finland Herceptin (FinHER), National Surgical Adjuvant Breast and Bowel Project (NSAPB-31), North Central Cancer Treatment Group (N9831), Herceptin Adjuvant (HERA) and Breast Cancer International Research Group (BCIRG-006). We estimated clinical impact measures - number needed to treat (NNT) and absolute risk reduction (ARR) - and total drug cost by protocol to avoid one single cancer recurrence. RESULTS. The largest ARR was 11.7% (95% CI: 2.2% to 21.2%) in the FinHER study, and the smallest in the nonanthracycline arm of the BCIRG trial, 4.9% (95% CI: 1.8% to 8.1%). The NNT was 8 (95% CI: 3 to 28) in the FinHER, 8 (95% CI: 7 to 11) in the NSABP-31/N9831, 12 (95% CI: 9 to 18) in the HERA, 14 (95% CI: 11 to 24) in the BCIRG/Anthracycline, and 17 (CI 95% CI: 12 to 34) in the BCIRG/Nonanthracycline. Drug cost to avoid one single cancer recurrence would be R$ 418,285.44 with the FinHER regimen, R$ 1,716,789.44 with the NSABP-31/N9831, R$ 2,481,891.58 with the HERA, R$ 2,963,634.62 with the BCIRG/Anthracicline, and R$ 3,930,520.43 with the BCIRG/Nonanthracycline (exchange rate: R$ 1.00 = USD 0.56). CONCLUSION. From an economic viewpoint, four to seven times more patients could benefit by using a short-course of trastuzumab at the initial adjuvant chemotherapy cycles (FinHER regimen) than by the prolonged trastuzumab administration as used in other adjuvant schedules.