Aspectos clínico-econômicos da quimioterapia adjuvante no câncer de mama HER-2 positivo / Clinical and economic issues in adjuvant chemotherapy for HER-2 positive breast cancer

RESUMO

OBJETIVO: Avaliar o impacto clínico e os custos do tratamento adjuvante para câncer de mama com superexpressão do receptor 2 do Fator de Crescimento Epidérmico (HER-2). MÉTODOS: Foram obtidas medidas de eficácia (sobrevida livre de doença em 3 anos) dos ensaios de fase III com trastuzumabe para o câncer de mama HER-2 positivo um estudo finlandês (FinHER), dois americanos (National Surgical Adjuvant Breast and Bowel Project - NSAPB-31 e North Central Cancer Treatment Group N9831) e dois multinacionais (Herceptin Adjuvant, HERA e Breast Cancer International Research Group, BCIRG-006), e calculadas medidas de impacto clínico redução de risco e número necessário para tratar (NNT). Foram estimados os custos com medicamentos antineoplásicos nestes diferentes regimes terapêuticos. RESULTADOS: A redução absoluta de risco com uso do trastuzumabe foi maior no estudo FinHER (11,7 por cento; IC 95 por cento 2,2 por cento a 21,2 por cento). O NNT no FinHER foi 8 (IC 95 por cento 3 a 28), 8 (IC 95 por cento 7 a 11) no NSABP-31/N9831, 12 (IC 95 por cento 9 a 18) no HERA, 14 (IC 95 por cento 11 a 24) no BCIRG/com antraciclinas e 17 (IC 95 por cento 12 a 34) no BCIRG/sem antraciclinas. O custo para evitar um caso de recidiva seria R$ 418.285,44 com o regime FinHER, R$ 1.716.789,44 no NSABP-31/N9831, R$ 2.481.891,58 no HERA, R$ 2.963.634,62 no BCIRG/com antraciclinas e R$ 3.930.520,43 no BCIRG/sem antraciclinas. CONCLUSÃO: Restringir o uso do trastuzumabe à fase inicial de quimioterapia adjuvante (FinHER) permite beneficiar, do ponto de vista econômico, quatro a nove vezes mais pacientes que a monoterapia adjuvante prolongada como usada nos demais protocolos.

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 percent (95 percent CI 2.2 percent to 21.2 percent) in the FinHER study, and the smallest in the nonanthracycline arm of the BCIRG trial, 4.9 percent (95 percent CI 1.8 percent to 8.1 percent). The NNT was 8 (95 percent CI 3 to 28) in the FinHER, 8 (95 percent CI 7 to 11) in the NSABP-31/N9831, 12 (95 percent CI 9 to 18) in the HERA, 14 (95 percent CI 11 to 24) in the BCIRG/Anthracycline, and 17 (CI 95 percent 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.