Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 38
Filtrar
Más filtros

Banco de datos
País/Región como asunto
Tipo del documento
Asunto de la revista
País de afiliación
Intervalo de año de publicación
1.
Gynecol Oncol ; 154(2): 420-425, 2019 08.
Artículo en Inglés | MEDLINE | ID: mdl-31229298

RESUMEN

PURPOSE: To compare patient/tumor characteristics and outcomes of Asians to Caucasian patients with epithelial ovarian cancer. METHODS: Ancillary data were pooled and analyzed from ten prospective randomized front-line Gynecologic Oncology Group clinical trials from 1996 to 2011. Demographic, clinicopathologic features, disease-specific and all-cause survival were analyzed. RESULTS: Of 7914 patients, 7641 were Caucasian and 273 Asian. When compared to Caucasians, Asians were younger at trial enrollment, had a better performance status, earlier-stage cancers (17.2% vs. 8.1% with stage I; p < 0.001), and were more likely to be of clear cell (15.8% vs. 6.2%, p < 0.001) and mucinous (3.3% vs. 1.9%, p < 0.001) histology. Asians had an improved 5-year disease-specific survival of 54.1% compared to 46.1% for Caucasians, p = 0.001. In multivariate analysis, the Asian race remained a significant prognostic factor for all-cause survival (HR: 0.84; 95% CI: 0.72-0.99; p = 0.04). Other factors predictive of improved survival included younger age, better performance status, optimal cytoreduction, earlier stage, non-clear cell histology, and lower grade tumors. CONCLUSION: Asians enrolled into phase III ovarian cancer clinical trials were younger, with better performance status, earlier-stage of disease, and have a greater number of clear cell and mucinous tumors. After adjusting for these prognostic factors, Asians have a better survival compared to Caucasians.


Asunto(s)
Pueblo Asiatico/estadística & datos numéricos , Carcinoma Epitelial de Ovario/diagnóstico , Carcinoma Epitelial de Ovario/mortalidad , Neoplasias Ováricas/diagnóstico , Neoplasias Ováricas/mortalidad , Población Blanca/estadística & datos numéricos , Anciano , Femenino , Humanos , Estimación de Kaplan-Meier , Persona de Mediana Edad , Pronóstico , Modelos de Riesgos Proporcionales , Estudios Prospectivos , Ensayos Clínicos Controlados Aleatorios como Asunto , Análisis de Supervivencia
3.
J Clin Oncol ; 41(25): 4077-4083, 2023 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-37643542

RESUMEN

Purpose: In randomized trials the combination of cisplatin and paclitaxel was superior to cisplatin and cyclophosphamide in advanced-stage epithelial ovarian cancer. Although in nonrandomized trials, carboplatin and paclitaxel was a less toxic and highly active combination regimen, there remained concern regarding its efficacy in patients with small-volume, resected, stage III disease. Thus, we conducted a noninferiority trial of cisplatin and paclitaxel versus carboplatin and paclitaxel in this population.Patients and Methods: Patients with advanced ovarian cancer and no residual mass greater than 1.0 cm after surgery were randomly assigned to receive cisplatin 75 mg/m2 plus a 24-hour infusion of paclitaxel 135 mg/m2 (arm I), or carboplatin area under the curve 7.5 intravenously plus paclitaxel 175 mg/m2 over 3 hours (arm II).Results: Seven hundred ninety-two eligible patients were enrolled onto the study. Prognostic factors were similar in the two treatment groups. Gastrointestinal, renal, and metabolic toxicity, as well as grade 4 leukopenia, were significantly more frequent in arm I. Grade 2 or greater thrombocytopenia was more common in arm II. Neurologic toxicity was similar in both regimens. Median progression-free survival and overall survival were 19.4 and 48.7 months, respectively, for arm I compared with 20.7 and 57.4 months, respectively, for arm II. The relative risk (RR) of progression for the carboplatin plus paclitaxel group was 0.88 (95% confidence interval [CI], 0.75 to 1.03) and the RR of death was 0.84 (95% CI, 0.70 to 1.02).Conclusion: In patients with advanced ovarian cancer, a chemotherapy regimen consisting of carboplatin plus paclitaxel results in less toxicity, is easier to administer, and is not inferior, when compared with cisplatin plus paclitaxel.

4.
Cancer Cell ; 1(2): 111-2, 2002 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-12086867

RESUMEN

Proteomic patterns in serum that discriminate between malignant and benign ovaries may provide a powerful tool for screening in high risk women.


Asunto(s)
Biología Computacional/métodos , Regulación Neoplásica de la Expresión Génica , Neoplasias Ováricas/química , Neoplasias Ováricas/diagnóstico , Proteoma/metabolismo , Biomarcadores de Tumor/metabolismo , Femenino , Humanos , Tamizaje Masivo
5.
Gynecol Oncol ; 122(3): 521-6, 2011 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-21683993

RESUMEN

OBJECTIVE: To assess the survival impact of initial disease distribution on patients with stage III epithelial ovarian cancer (EOC) cytoreduced to microscopic residual. METHODS: We reviewed data from 417 stage III EOC patients cytoreduced to microscopic disease and given adjuvant intravenous platinum/paclitaxel on one of three randomized Gynecologic Oncology Group (GOG) trials. We subdivided patients into three groups based on preoperative disease burden: (1) minimal disease (MD) defined by pelvic tumor and retroperitoneal metastasis (2) abdominal peritoneal disease (APD) with disease limited to the pelvis, retroperitoneum, lower abdomen and omentum; and (3) upper abdominal disease (UAD) with disease affecting the diaphragm, spleen, liver or pancreas. We assessed the survival impact of potential prognostic factors, focusing on initial disease distribution using a proportional hazards model and estimated Kaplan-Meier survival curves. RESULTS: The study groups had similar clinicopathologic characteristics. Median overall survival (OS) was not reached in MD patients compared to 80 and 56 months in the APD and UAD groups (P<0.05). The five-year survival percentages for MD, APD, and UAD were 67%, 63%, and 45%. In multivariate analysis, the UAD group had a significantly worse prognosis than MD and APD both individually and combined (Progression Free Survival (PFS) Hazards Ratio (HR) 1.44; P=0.008 and OS HR 1.77; P=0.0004 compared to MD+APD). CONCLUSION: Stage III EOC patients with initial disease in the upper abdomen have a worse prognosis despite cytoreductive surgery to microscopic residual implying that factors beyond cytoreductive effort are important in predicting survival.


Asunto(s)
Neoplasias Glandulares y Epiteliales/tratamiento farmacológico , Neoplasias Glandulares y Epiteliales/patología , Neoplasias Ováricas/tratamiento farmacológico , Neoplasias Ováricas/patología , Anciano , Protocolos de Quimioterapia Combinada Antineoplásica/administración & dosificación , Carboplatino/administración & dosificación , Carcinoma Epitelial de Ovario , Cisplatino/administración & dosificación , Supervivencia sin Enfermedad , Femenino , Humanos , Estimación de Kaplan-Meier , Persona de Mediana Edad , Estadificación de Neoplasias , Neoplasia Residual , Paclitaxel/administración & dosificación , Modelos de Riesgos Proporcionales , Tasa de Supervivencia
6.
Clin Cancer Res ; 13(14): 4261-70, 2007 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-17634556

RESUMEN

PURPOSE: mTOR (mammalian target of rapamycin) plays a central role in regulating cell growth and cell cycle progression and is regarded as a promising therapeutic target. We examined whether mTOR inhibition by RAD001 (everolimus) is therapeutically efficacious in the treatment of ovarian cancer as a single agent and in combination with cisplatin. EXPERIMENTAL DESIGN: Using four human ovarian cancer cell lines, we determined the effect of RAD001 by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, Western blot, and apoptosis assays. We evaluated the association between phospho-AKT/mTOR activity and RAD001 sensitivity. We also determined the effect of RAD001 on tumor growth and malignancy using mice inoculated with human ovarian cancer cells. RESULTS: RAD001 markedly inhibited cell proliferation of human ovarian carcinoma cells with high AKT activity (OVCAR10 and SKOV-3), but the effect was minimal in cells with low AKT activity (OVCAR4 and OVCAR5). Sensitivity to RAD001 was independent of p53 expression. RAD001 inhibited the phosphorylation of downstream 4E-BP1 and p70S6 kinase and attenuated the expression of Myc. RAD001 also attenuated the expression of HIF-1 alpha and vascular endothelial growth factor, important factors in angiogenesis and tumor invasiveness. RAD001 enhanced cisplatin-induced apoptosis in cells with high AKT/mTOR activity, with minimal effect in cells with low AKT-mTOR activity. Mouse xenografts of SKOV-3 cells revealed that RAD001 inhibits tumor growth, angiogenesis, and i.p. dissemination and ascites production and prolongs survival. Moreover, treatment with RAD001 significantly enhanced the therapeutic efficacy of cisplatin in vivo. CONCLUSION: These results indicate that RAD001 could have therapeutic efficacy in human ovarian cancers with hyperactivated AKT/mTOR signaling.


Asunto(s)
Apoptosis/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Cisplatino/uso terapéutico , Sirolimus/análogos & derivados , Antineoplásicos/farmacología , División Celular/efectos de los fármacos , Línea Celular , Línea Celular Tumoral , Everolimus , Femenino , Humanos , Inmunosupresores/uso terapéutico , Cinética , Neoplasias Ováricas , Sirolimus/uso terapéutico
8.
Semin Oncol ; 33(2 Suppl 6): S3-11, 2006 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-16716797

RESUMEN

Current systemic therapy for ovarian cancer consists of a combination of carboplatin and paclitaxel. While the majority of patients achieve clinical complete remission after six cycles of chemotherapy, the relapse rate stands at over 50%. Median survival time for patients after recurrence is approximately 2 years. New treatment approaches for patients with advanced ovarian cancer include consolidation and maintenance therapy, intraperitoneal administration of cytotoxic agents, new combination chemotherapy regimens, the development of new cytotoxic agents, and molecular-targeted therapies. These agents will be evaluated either singularly or with chemotherapy. Currently, the Gynecologic Oncology Group is evaluating a combination of bevacizumab together with paclitaxel and carboplatin in previously untreated patients with advanced ovarian cancer. This trial is based on phase II data that suggest that bevacizumab as a single agent has significant activity in patients with recurrent ovarian cancer. In addition, the Gynecologic Oncology Group will be conducting phase II trials of different combinations of intraperitoneal chemotherapy in an effort to decrease toxicity associated with current intraperitoneal regimens that have shown an improvement in survival in patients with small-volume stage III disease. The Gynecologic Oncology Group will also be conducting a trial of maintenance therapy in patients who enter clinical complete remission with paclitaxel plus carboplatin, comparing observation with monthly paclitaxel or monthly paclitaxel poliglumex. Novel new cytotoxic and biologic agents are also being evaluated as single agents in phase II trials in patients with recurrent ovarian cancer.


Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Recurrencia Local de Neoplasia/tratamiento farmacológico , Neoplasias Ováricas/tratamiento farmacológico , Anticuerpos Monoclonales/administración & dosificación , Anticuerpos Monoclonales Humanizados , Bevacizumab , Carboplatino/administración & dosificación , Árboles de Decisión , Vías de Administración de Medicamentos , Femenino , Humanos , Infusiones Parenterales , Oncología Médica/tendencias , Recurrencia Local de Neoplasia/mortalidad , Recurrencia Local de Neoplasia/patología , Estadificación de Neoplasias , Neoplasias Ováricas/mortalidad , Neoplasias Ováricas/patología , Paclitaxel/administración & dosificación , Ensayos Clínicos Controlados Aleatorios como Asunto
9.
J Clin Oncol ; 21(17): 3194-200, 2003 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-12860964

RESUMEN

PURPOSE: In randomized trials the combination of cisplatin and paclitaxel was superior to cisplatin and cyclophosphamide in advanced-stage epithelial ovarian cancer. Although in nonrandomized trials, carboplatin and paclitaxel was a less toxic and highly active combination regimen, there remained concern regarding its efficacy in patients with small-volume, resected, stage III disease. Thus, we conducted a noninferiority trial of cisplatin and paclitaxel versus carboplatin and paclitaxel in this population. PATIENTS AND METHODS: Patients with advanced ovarian cancer and no residual mass greater than 1.0 cm after surgery were randomly assigned to receive cisplatin 75 mg/m2 plus a 24-hour infusion of paclitaxel 135 mg/m2 (arm I), or carboplatin area under the curve 7.5 intravenously plus paclitaxel 175 mg/m2 over 3 hours (arm II). RESULTS: Seven hundred ninety-two eligible patients were enrolled onto the study. Prognostic factors were similar in the two treatment groups. Gastrointestinal, renal, and metabolic toxicity, as well as grade 4 leukopenia, were significantly more frequent in arm I. Grade 2 or greater thrombocytopenia was more common in arm II. Neurologic toxicity was similar in both regimens. Median progression-free survival and overall survival were 19.4 and 48.7 months, respectively, for arm I compared with 20.7 and 57.4 months, respectively, for arm II. The relative risk (RR) of progression for the carboplatin plus paclitaxel group was 0.88 (95% confidence interval [CI], 0.75 to 1.03) and the RR of death was 0.84 (95% CI, 0.70 to 1.02). CONCLUSION: In patients with advanced ovarian cancer, a chemotherapy regimen consisting of carboplatin plus paclitaxel results in less toxicity, is easier to administer, and is not inferior, when compared with cisplatin plus paclitaxel.


Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Carboplatino/administración & dosificación , Cisplatino/administración & dosificación , Neoplasias Ováricas/tratamiento farmacológico , Paclitaxel/administración & dosificación , Adulto , Anciano , Anciano de 80 o más Años , Área Bajo la Curva , Terapia Combinada , Femenino , Humanos , Persona de Mediana Edad , Estadificación de Neoplasias , Neoplasias Ováricas/patología , Neoplasias Ováricas/cirugía , Modelos de Riesgos Proporcionales , Estadísticas no Paramétricas , Análisis de Supervivencia , Resultado del Tratamiento
10.
Semin Oncol ; 32(4 Suppl 6): S4-8, 2005 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-16143161

RESUMEN

Most patients with advanced ovarian cancer achieve a clinical complete remission following cytoreductive surgery and chemotherapy with paclitaxel plus carboplatin. However, a majority of these patients will ultimately recur, and second-line treatment for this group of patients is an important aspect of management of this disease as well as an area of active clinical investigation. Until recently, for patients with platinum-sensitive ovarian cancer (more than 6-month disease-free interval), chemotherapy with single-agent carboplatin was frequently recommended. However, two recent prospective randomized trials have shown that combination chemotherapy produces higher response rates and improvement in progression-free survival compared with treatment with single-agent carboplatin. One trial compared treatment with paclitaxel plus a platinum compound with re-treatment with platinum, and a second trial compared carboplatin plus gemcitabine re-treatment against carboplatin in patients with platinum-sensitive recurrent ovarian cancer. Both trials showed a 3-month improvement in progression-free survival in patients treated with the combination, as well as acceptable toxicity. In the absence of a prospective randomized trial comparing these two regimens in patients with platinum-sensitive recurrent ovarian cancer, the choice of which combination to use may depend on toxicity considerations.


Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Recurrencia Local de Neoplasia/tratamiento farmacológico , Neoplasias Ováricas/tratamiento farmacológico , Carboplatino/administración & dosificación , Desoxicitidina/administración & dosificación , Desoxicitidina/análogos & derivados , Supervivencia sin Enfermedad , Femenino , Humanos , Neoplasias Ováricas/mortalidad , Tasa de Supervivencia , Gemcitabina
12.
Semin Oncol ; 29(1 Suppl 1): 32-42, 2002 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-11840418

RESUMEN

Standard chemotherapy for previously untreated patients with advanced ovarian cancer consists of the combination of a taxane and a platinum compound. While the majority of patients respond to therapy, median time to progression is less than 2 years. Patients with recurrent disease frequently respond to second-line treatments, but the impact on survival remains uncertain. Consequently, new treatment approaches are needed. Based on the results of phase II trials that demonstrated activity in previously treated patients with ovarian cancer, new combination regimens are being tested in which drugs such as gemcitabine, topotecan, or encapsulated doxorubicin are added to or sequenced with carboplatin plus paclitaxel. In addition, new platinum and taxane analogs are also under clinical development. Biological approaches to the treatment of patients with ovarian cancer are also in clinical development and include drugs that interfere with angiogenesis, matrix metalloproteinases, and signal transduction pathways. These drugs are currently being tested in previously treated patients with recurrent ovarian cancer. However, ultimately there may be a new paradigm of treatment in which patients receive combination chemotherapy together with a biologic agent for six cycles of treatment and, at that point, the chemotherapy is stopped and patients continue with chronic maintenance biologic therapy. Semin Oncol 29 (suppl 1):32-42.


Asunto(s)
Antineoplásicos/uso terapéutico , Terapia Biológica , Terapia Genética , Neoplasias Ováricas/terapia , Adyuvantes Inmunológicos/uso terapéutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Vacunas contra el Cáncer/uso terapéutico , Terapia Combinada , Resistencia a Antineoplásicos , Femenino , Humanos , Neoplasias Ováricas/tratamiento farmacológico
18.
Cancer ; 115(7): 1395-403, 2009 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-19195045

RESUMEN

BACKGROUND: There are limited data regarding unique clinical or laboratory features associated with advanced clear cell (CC) and mucinous (MU) epithelial ovarian cancers (EOC), particularly the relationship between CA-125 antigen levels and prognosis. METHODS: A retrospective review of 7 previously reported Gynecologic Oncology Group phase 3 trials in patients with stage III/IV EOC was conducted. A variety of clinical parameters were examined, including the impact of baseline and changes in the CA-125 level after treatment of CC and MU EOC on progression-free (PFS) and overall survival (OS). RESULTS: Clinical outcomes among patients with advanced CC and MU EOC were significantly worse when compared with other cell types (median PFS, 9.7 vs 7.0 vs 16.7 months, respectively, P < .001; median OS, 19.4 vs 11.3 vs 40.5 months, respectively, P < .001). Suboptimal debulking was associated with significantly decreased PFS and OS among both. Although baseline CA-125 values were lower in CC (median, 154 micron/mL) and MU (100 micron/mL), compared with other cell types (275 micron/mL), this level did not appear to influence outcome among these 2 specific subtypes of EOC. However, an elevated level of CA-125 at the end of chemotherapy was significantly associated with decreased PFS and OS (P < .01 for all). CONCLUSIONS: Surgical debulking status is the most important variable at prechemotherapy predictive of prognosis among advanced CC and MU EOC patients. Changes in the CA-125 levels at the end treatment as compared with baseline can serve as valid indicators of PFS and OS, and likely the degree of inherent chemosensitivity.


Asunto(s)
Adenocarcinoma de Células Claras/tratamiento farmacológico , Adenocarcinoma Mucinoso/tratamiento farmacológico , Adenocarcinoma Mucinoso/metabolismo , Antígeno Ca-125/sangre , Neoplasias Ováricas/tratamiento farmacológico , Adenocarcinoma de Células Claras/metabolismo , Ensayos Clínicos Fase III como Asunto , Femenino , Humanos , Neoplasias Ováricas/metabolismo , Valor Predictivo de las Pruebas , Pronóstico , Ensayos Clínicos Controlados Aleatorios como Asunto , Resultado del Tratamiento
19.
Cancer ; 115(5): 1028-35, 2009 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-19156927

RESUMEN

BACKGROUND: The objective of the current study was to determine the prognostic significance of a pretreatment serum CA 125 level in patients with advanced epithelial ovarian carcinoma (EOC) who received treatment with a standard chemotherapy regimen. METHODS: Patients with International Federation of Gynecology and Obstetrics stage III/IV ovarian carcinoma who were on 1 of 7 Gynecologic Oncology Group (GOG) phase 3 trials and received treatment with a standard regimen of intravenous cisplatin and paclitaxel were included. A Cox regression model was used to assess the impact of CA 125 levels drawn before the initiation of chemotherapy on progression-free survival (PFS) both overall and by subgroup, including surgical debulking status, disease stage, and histologic subtype. RESULTS: In total, 1,299 patients who were on the cisplatin/paclitaxel arms of the GOG trials were eligible. The median CA 125 level was 246 U/mL. Only 7.6% of patients had a normal CA 125 level (

Asunto(s)
Biomarcadores de Tumor/sangre , Antígeno Ca-125/sangre , Carcinoma/diagnóstico , Neoplasias Ováricas/diagnóstico , Anciano , Carcinoma/sangre , Carcinoma/patología , Carcinoma/terapia , Supervivencia sin Enfermedad , Femenino , Humanos , Persona de Mediana Edad , Neoplasias Ováricas/sangre , Neoplasias Ováricas/patología , Neoplasias Ováricas/terapia , Pronóstico , Ensayos Clínicos Controlados Aleatorios como Asunto
20.
J Clin Oncol ; 26(2): 313-25, 2008 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-18086794

RESUMEN

A MESSAGE FROM ASCO'S PRESIDENT: For the third year, the American Society of Clinical Oncology (ASCO) is publishing Clinical Cancer Advances: Major Research Advances in Cancer Treatment, Prevention, and Screening, an annual review of the most significant cancer research presented or published over the past year. ASCO publishes this report to demonstrate the important progress being made on the front lines of clinical cancer research today. The report is intended to give all those with an interest in cancer care-the general public, cancer patients and organizations, policymakers, oncologists, and other medical professionals-an accessible summary of the year's most important cancer research advances. These pages report on the use of magnetic resonance imaging for breast cancer screening, the association between hormone replacement therapy and breast cancer incidence, the link between human papillomavirus and head and neck cancers, and the use of radiation therapy to prevent lung cancer from spreading. They also report on effective new targeted therapies for cancers that have been historically difficult to treat, such as liver cancer and kidney cancer, among many others. A total of 24 advances are featured in this year's report. These advances and many more over the past several years show that the nation's long-term investment in cancer research is paying off. But there are disturbing signs that progress could slow. We are now in the midst of the longest sustained period of flat government funding for cancer research in history. The budgets for the National Institutes of Health and the National Cancer Institute (NCI) have been unchanged for four years. When adjusted for inflation, cancer research funding has actually declined 12% since 2004. These budget constraints limit the NCI's ability to fund promising cancer research. In the past several years the number of grants that the NCI has been able to fund has significantly decreased; this year, in response to just the threat of a 10% budget cut, the nation's Clinical Trials Cooperative Groups reduced the number of patients participating in clinical trials by almost 2,000 and senior researchers report that many of the brightest young minds no longer see the promise of a career in science, choosing other careers instead. It's time to renew the nation's commitment to cancer research. Without additional support, the opportunity to build on the extraordinary progress to date will be lost or delayed. This report demonstrates the essential role that clinical cancer research plays in finding new and better ways to care for the more than 1.4 million people expected to be diagnosed with cancer this year. I want to thank the Editorial Board members, the Specialty Editors, and the ASCO Cancer Communications Committee for their dedicated work to develop this report. I hope you find it useful. Sincerely, Nancy E. Davidson, MD President American Society of Clinical Oncology.


Asunto(s)
Oncología Médica/tendencias , Neoplasias/terapia , Investigación Biomédica , Neoplasias de Cabeza y Cuello/virología , Terapia de Reemplazo de Hormonas , Humanos , Neoplasias Pulmonares/patología , Neoplasias Pulmonares/radioterapia , Imagen por Resonancia Magnética , Neoplasias/diagnóstico , Neoplasias/prevención & control , Neoplasias/virología , Sociedades Médicas , Estados Unidos
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA