Influência de variáveis clinicopatológicas sobre a eficácia da quimioterapia neoadjuvante do câncer de mama / Influence of Clinicopathological Variables on the Efficacy of Neoadjuvant Chemotherapy of Breast Cancer

Introdução: A quimioterapia neoadjuvante do câncer de mama visa à redução da extensão tumoral e da área cirúrgica, favorecendo a conservação da mama e a sobrevida pós-mastectomia. O grau de resposta patológica, baseado no tamanho do tumor residual e no grau de acometimento linfonodal após ressecção tumoral, tem sido proposto como desfecho primário da eficácia antineoplásica, auxiliando a identificação de causas de falha terapêutica. Objetivo: Avaliar o impactode fatores clinicopatológicos sobre o grau de resposta à quimioterapia neoadjuvante do câncer de mama. Método: Uma coorte de mulheres com câncer de mama unilateral não metastático, submetidas à quimioterapia neoadjuvante com doxorrubicina e docetaxel, foi avaliada quanto ao grau de resposta patológica. Resultados: Foram avaliadas 227 pacientes com desfecho clínico definido após tratamento quimioterápico neoadjuvante, entre as quais, 4,8%tiveram resposta patológica completa (ausência de remanescentes tumorais na mama e nos linfonodos axilares) e 5,7% apresentaram progressão de doença. As variáveis associadas a maior risco de falha terapêutica foram: comprometimento linfonodal em qualquer grau (OR=15,25; IC95%=2,11-110,01) e positividade para receptor de estrogênio (OR=14,62;IC95%=3,05-70,01). Como consequência, houve melhor perfil de resposta para pacientes com tumores do subtipo molecular HER2 (OR=0,04; IC95%=0,00-0,40) ou triplo-negativo (OR=0,08; IC95%=0,00-0,60) em comparação ao tipo luminal A. Conclusão: A resposta tumoral à quimioterapia neoadjuvante não foi afetada por comorbidades sistêmicas, mas é influenciada pela expressão de receptores de estrogênio

Introduction:neoadjuvant chemotherapy for breast cancer aims to reduce the extent of the tumor and the surgicalarea, favoring breast conservation and patient survival after mastectomy. The degree of pathological response basedon tumor size and the degree of residual lymph node after tumor resection has been proposed as a primary out come of antineoplastic efficacy, and may help identifying individual causes of treatment failure...

Mechanisms of the UTP-induced tension in mammalian skeletal muscles

The mechanisms of UTP-induced tension in human and rat skinned fibers were investigated using isometric tension recordings, electrophysiological techniques and biochemical methods. In fast-type fibers from rat extensor digitorum longus (EDL) the UTP-induced tension: a) required previous loading of CA2+ into the sarcoplasmic reticulum (SR); b) was inhibited by previous exposure to caffeine; c) was abolished by functional disruption of the SR; d) was not affected by blockade of the SR Ca2+-release channels by ruthenium red or heparin; e) was prevented by spermidine. These data point to the SR as the target of UTP action and suggest a pathway of UTP-induced Ca2+-release independent of the ryanodine- or the IP3-sensitive Ca2+-release channels. Accordingly, UTP failed to stimulate the electrophysiological activity of ryanodine-sensitive channels, incorporated into lipid bilayers. We suggest that UTP-induced Ca2+-release might occur via the channel form of the SR Ca2+-ATPase. The UTP-induced tension in human slow-type fibers was not affected by the SR Ca2+ content or by disruption of the SR, but was accompanied by changes in the tension-pCa relationship, namely increase in maximum Ca2+-activated tension, and in apparent Ca2+-affinity of troponin. The UTP-induced tension in slow-type fibers from rat soleus was partially inhibited by Ca2+-depletion from, or by disruption of the SR, and was accompanied by changes in tension/pCa relationship, similar to those observed in human fibers. Both in skinned fibers and in isolated SR vesicles, UTP was less effective than ATP as a substrate for the SR Ca2+-ATPase. This effect might contribute to UTP-induced tension.