RESUMEN
PURPOSE: In a previous study of treatment for advanced colorectal cancer, the LV5FU2 regimen, comprising leucovorin (LV) plus bolus and infusional fluorouracil (5FU) every 2 weeks, was superior to the standard North Central Cancer Treatment Group/Mayo Clinic 5-day bolus 5FU/LV regimen. This phase III study investigated the effect of combining oxaliplatin with LV5FU2, with progression-free survival as the primary end point. PATIENTS AND METHODS: Four hundred twenty previously untreated patients with measurable disease were randomized to receive a 2-hour infusion of LV (200 mg/m2/d) followed by a 5FU bolus (400 mg/m2/d) and 22-hour infusion (600 mg/m2/d) for 2 consecutive days every 2 weeks, either alone or together with oxaliplatin 85 mg/m2 as a 2-hour infusion on day 1. RESULTS: Patients allocated to oxaliplatin plus LV5FU2 had significantly longer progression-free survival (median, 9.0 v 6.2 months; P = .0003) and better response rate (50.7% v 22.3%; P = .0001) when compared with the control arm. The improvement in overall survival did not reach significance (median, 16.2 v 14.7 months; P = .12). LV5FU2 plus oxaliplatin gave higher frequencies of National Cancer Institute common toxicity criteria grade 3/4 neutropenia (41.7% v 5.3% of patients), grade 3/4 diarrhea (11.9% v 5.3%), and grade 3 neurosensory toxicity (18.2% v 0%), but this did not result in impairment of quality of life (QoL). Survival without disease progression or deterioration in global health status was longer in patients allocated to oxaliplatin treatment (P = .004). CONCLUSION: The LV5FU2-oxaliplatin combination seems beneficial as first-line therapy in advanced colorectal cancer, demonstrating a prolonged progression-free survival with acceptable tolerability and maintenance of QoL.
Asunto(s)
Oxaliplatino , Neoplasias del Recto , Quimioradioterapia , Quimioterapia Adyuvante , HumanosRESUMEN
This paper presents the largest study in Cyprus evaluating the frequency and distribution of BRCA1/2 mutations in a high risk patient cohort. Deleterious mutations in the BRCA1/2 genes were identified in 68 of the 527 patients tested (13%). It is of interest that a quarter of those tested positive, did not have an extensive family history of breast/ovarian cancer but were diagnosed with early onset breast cancer, ovarian cancer under the age of 60 or triple negative breast cancer. The spectrum of mutations identified in our patient cohort is different compared to other Mediterranean countries. Furthermore, several of the mutations detected are novel and have not been identified in other ethnic populations. This highlights the importance of operating a national reference center for cancer genetic diagnosis which offers services tailored to the needs of the Cypriot population.
Asunto(s)
Proteína BRCA1/genética , Proteína BRCA2/genética , Neoplasias Ováricas/genética , Neoplasias de la Mama Triple Negativas/genética , Adulto , Anciano , Chipre/epidemiología , Femenino , Predisposición Genética a la Enfermedad , Pruebas Genéticas , Genética de Población , Humanos , Persona de Mediana Edad , Epidemiología Molecular , Mutación , Neoplasias Ováricas/epidemiología , Neoplasias de la Mama Triple Negativas/epidemiologíaRESUMEN
Colorectal cancer (CRC) is one of the most common malignancies in Western countries. Over the last 20 years, and the last decade in particular, the clinical outcome for patients with metastatic CRC (mCRC) has improved greatly due not only to an increase in the number of patients being referred for and undergoing surgical resection of their localised metastatic disease but also to a more strategic approach to the delivery of systemic therapy and an expansion in the use of ablative techniques. This reflects the increase in the number of patients that are being managed within a multidisciplinary team environment and specialist cancer centres, and the emergence over the same time period not only of improved imaging techniques but also prognostic and predictive molecular markers. Treatment decisions for patients with mCRC must be evidence-based. Thus, these ESMO consensus guidelines have been developed based on the current available evidence to provide a series of evidence-based recommendations to assist in the treatment and management of patients with mCRC in this rapidly evolving treatment setting.
Asunto(s)
Biomarcadores de Tumor/genética , Neoplasias Colorrectales/tratamiento farmacológico , Pronóstico , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/patología , Guías como Asunto , Humanos , Terapia Molecular Dirigida , Metástasis de la NeoplasiaRESUMEN
Compared with intravenous (i.v.) chemotherapy, oral administration is convenient, requires fewer healthcare resources, is generally preferred by patients, and may be appropriate in older people with breast, colorectal and lung cancers. The effects of organ dysfunction on drug metabolism and drug interactions in patients with multiple comorbidities must be considered but are not specific to oral chemotherapy. Single-agent oral chemotherapy with capecitabine or vinorelbine is active in older patients with advanced or metastatic breast cancer. Choice of treatment is based mainly on different safety profiles. In the adjuvant treatment of colorectal cancer (CRC), single-agent oral capecitabine is an effective alternative to i.v. fluorouracil (5-FU) regimens. In metastatic CRC, oral, single-agent capecitabine has recently shown encouraging median overall survival in combination with bevacizumab. In non-small cell lung cancer, fit older patients, like their younger counterparts, benefit from platinum-based doublets, with carboplatin preferred to cisplatin. Single agent vinorelbine is an option for those less suited to combination chemotherapy, and oral may be an alternative to i.v. administration. For elderly cancer patients in general, metronomic chemotherapy combines good tolerability with acceptable activity.
Asunto(s)
Antineoplásicos/uso terapéutico , Cumplimiento de la Medicación/estadística & datos numéricos , Neoplasias/tratamiento farmacológico , Prioridad del Paciente/estadística & datos numéricos , Administración Oral , Anciano , Supervivencia sin Enfermedad , Humanos , Persona de Mediana Edad , Resultado del TratamientoRESUMEN
Colorectal cancer (CRC) is one of the most commonly diagnosed cancers in Europe and worldwide, with the peak incidence in patients >70 years of age. However, as the treatment algorithms for the treatment of patients with CRC become ever more complex, it is clear that a significant percentage of older CRC patients (>70 years) are being less than optimally treated. This document provides a summary of an International Society of Geriatric Oncology (SIOG) task force meeting convened in Paris in 2013 to update the existing expert recommendations for the treatment of older (geriatric) CRC patients published in 2009 and includes overviews of the recent data on epidemiology, geriatric assessment as it relates to surgery and oncology, and the ability of older CRC patients to tolerate surgery, adjuvant chemotherapy, treatment of their metastatic disease including palliative chemotherapy with and without the use of the biologics, and finally the use of adjuvant and palliative radiotherapy in the treatment of older rectal cancer patients. An overview of each area was presented by one of the task force experts and comments invited from other task force members.
Asunto(s)
Neoplasias Colorrectales/terapia , Consenso , Geriatría/normas , Internacionalidad , Sociedades Médicas/normas , Anciano , Anciano de 80 o más Años , Quimioterapia Adyuvante/métodos , Quimioterapia Adyuvante/normas , Neoplasias Colorrectales/diagnóstico , Neoplasias Colorrectales/epidemiología , Europa (Continente)/epidemiología , Evaluación Geriátrica/métodos , Geriatría/métodos , Humanos , Cuidados Paliativos/métodos , Cuidados Paliativos/normas , Resultado del TratamientoAsunto(s)
Inhibidores de la Angiogénesis/efectos adversos , Anticuerpos Monoclonales Humanizados/efectos adversos , Neovascularización Patológica/tratamiento farmacológico , Neoplasias Ováricas/tratamiento farmacológico , Trastornos de la Voz/inducido químicamente , Bevacizumab , Femenino , Humanos , Persona de Mediana Edad , Neovascularización Patológica/complicaciones , Neoplasias Ováricas/irrigación sanguínea , Neoplasias Ováricas/complicaciones , Ovario/irrigación sanguínea , Ovario/efectos de los fármacos , Pliegues Vocales/irrigación sanguínea , Pliegues Vocales/efectos de los fármacos , Pliegues Vocales/patología , Trastornos de la Voz/complicaciones , Trastornos de la Voz/patologíaRESUMEN
Adenocarcinoma of the pancreas carries a uniformly poor prognosis with high rates of loco-regional as well as systemic recurrence. Outcomes remain poor, even for early stage and resectable disease. It is perceived as inherently resistant to most of the currently available treatment options. Evidence supports the need for adjuvant chemotherapy but controversy remains in relation to the use of combined therapy, novel agents and the most appropriate timing of therapy. Despite no clear consensus, mainstay of treatment following resection is based primarily on single agent gemcitabine. Promising new agents and molecules of prognostic as well as predictive value under evaluation offer intriguing data, despite issues surrounding adjuvant therapy strategies. In this article, we sought to review the different therapeutic adjuvant modalities and future directions.
Asunto(s)
Adenocarcinoma/terapia , Antineoplásicos/uso terapéutico , Neoplasias Pancreáticas/terapia , Adenocarcinoma/metabolismo , Adenocarcinoma/mortalidad , Biomarcadores de Tumor/metabolismo , Quimioterapia Adyuvante , Humanos , Inmunoterapia , Terapia Molecular Dirigida , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/mortalidad , Ensayos Clínicos Controlados Aleatorios como Asunto , Resultado del TratamientoRESUMEN
Barrett's esophagus (BE) is a major precursor factor of esophageal cancer (EC). The appropriate management of patients with BE depends on the presence or not of dysplasia and the type of dysplasia that occurs. Due to the small proportion of BE patients that progress to cancer, the value of surveillance programs are a matter of debate. On the contrary, in high risk group of patients surveillance programs have significant impact. Large prospective trials are needed to define the optimal management strategy. Elucidation of carcinogenesis' steps and signal transduction pathways could reveal potential biomarkers in the order of early prediction for a highly malignant neoplasm with dismal prognosis. An efficacious tailored-made manner focusing to the safety profile and associated costs should be practised for less severe disease. In this review a thorough investigation of all available methods dealing with the clinical management of BE is provided.
Asunto(s)
Esófago de Barrett/complicaciones , Esófago de Barrett/terapia , Neoplasias Esofágicas/etiología , Ablación por Catéter , Criocirugía , Humanos , Fotoquimioterapia , Factores de RiesgoRESUMEN
As a result of an increasing life expectancy, the incidence of colon cancer in the older population is rising. As a consequence oncologists and their older patients commonly face the dilemma of whether or not to give/receive treatment for colon cancer. However, the paucity of large, well conducted prospective trials makes it difficult to provide evidence-based clinical recommendations for these patients. The current evidence supports the safety and efficacy of treatment for colon cancer in fit older patients and demonstrates that treatment outcome can be similar to that of their younger counterparts. However, it should be noted that these data are derived from retrospective studies which are likely to suffer from selection bias. Despite a growing body of data, further work is still needed to establish optimal strategies to care for this special population and prospective specific trials for older colon cancer patients are clearly needed.
Asunto(s)
Neoplasias del Colon/tratamiento farmacológico , Neoplasias del Colon/cirugía , Factores de Edad , Anciano , Quimioterapia Adyuvante , Ensayos Clínicos como Asunto , Evaluación Geriátrica , Humanos , Estudios RetrospectivosRESUMEN
Colorectal cancer (CRC) is one of the commonest malignancies of Western countries, with approximately half the incidence occurring in patients >70 years of age. Elderly CRC patients, however, are understaged, undertreated and underrepresented in clinical trials. The International Society of Geriatric Oncology created a task force with a view to assessing the potential for developing guidelines for the treatment of elderly (geriatric) CRC patients. A review of the evidence presented by the task force members confirmed the paucity of clinical trial data in elderly people and the lack of evidence-based guidelines. However, recommendations have been proposed on the basis of the available data and on the emerging evidence that treatment outcomes for fit, elderly CRC patients can be similar to those of younger patients. It is hoped that these will pave the way for formal treatment guidelines based upon solid scientific evidence in the future.
Asunto(s)
Anciano , Neoplasias Colorrectales/terapia , Directrices para la Planificación en Salud , Anciano de 80 o más Años , Neoplasias Colorrectales/diagnóstico , Neoplasias Colorrectales/mortalidad , Neoplasias Colorrectales/patología , Humanos , Cuidados Paliativos/métodos , Radioterapia Adyuvante/métodos , Sociedades MédicasAsunto(s)
Neoplasias del Colon/tratamiento farmacológico , Neoplasias del Colon/cirugía , Factores de Edad , Anciano , Anciano de 80 o más Años , Quimioterapia Adyuvante , Neoplasias del Colon/patología , Geriatría/métodos , Humanos , Persona de Mediana Edad , Metástasis de la Neoplasia , Estadificación de NeoplasiasRESUMEN
Familial adenomatous polyposis (FAP) is one of the two commonest familial syndromes that predispose to colorectal cancer. FAP is caused by mutations in the adenomatous polyposis coli (APC) tumour suppressor gene that has a high penetrance. The disease is characterized by the occurrence of hundreds to thousands of colorectal polyps, which if left untreated give rise to colorectal cancer. In Cyprus, there are no molecular data available as yet on families with FAP. This work presents the results of APC analysis in our population for the first time. The APC gene was analyzed in 33 DNA samples from 20 individuals belonging to four FAP families and 13 patients with sporadic polyposis. We identified three truncating mutations, four missense mutations and 11 polymorphisms. It is of interest that two of the three truncating mutations, 2307delA and Q1242X, are novel, which supports the existence of a unique genetic pool in the Cypriot population. This ethnic molecular study in addition to highlighting population heterogeneity also contributes to phenotype-genotype associations that are essential for the clinical management of FAP families in Cyprus.
Asunto(s)
Poliposis Adenomatosa del Colon/genética , Genes APC , Mutación de Línea Germinal , Poliposis Adenomatosa del Colon/diagnóstico , Adolescente , Adulto , Chipre/etnología , Análisis Mutacional de ADN , Femenino , Humanos , Masculino , Persona de Mediana Edad , Polimorfismo GenéticoRESUMEN
The aim of this phase II study was to investigate the tolerance and efficacy of a second-line irinotecan/mitomycin C combination in patients with advanced gastric or colorectal cancer, pretreated with 5-fluorouracil. Forty patients who had received 5-fluorouracil-based chemotherapy for advanced disease or adjuvant 5-fluorouracil treatment were enrolled. Chemotherapy consisted of irinotecan 125 mg/m2 and mitomycin C 5 mg/m2, given every 2 weeks. Treatment was continued until progression or limiting toxicity occurred. Five partial responses (12.5%), 22 cases of stable disease (55%) and 13 of progression (32.5%) were registered, giving an overall response rate of 12.5% [95% confidence interval (CI), 4.2-26.8%] and an overall control of tumor growth in 67.5% (95% CI, 50.8-81.4%) of patients. Median progression-free survival was 5 months, median survival time 8 months, and 1-year probability of survival was 21.6%. Diarrhea and neutropenia affected 25% and 12.5% of patients respectively, with only 7.5% experiencing grade 3-4 toxicity. There were no chemotherapy-related deaths or hospitalizations. This combination regimen was shown to be moderately effective with substantially lower toxicity than irinotecan monotherapy in 5-fluorouracil-pretreated patients with advanced gastric or colorectal cancer. It may represent an attractive option in patients at high risk for developing specific irinotecan toxicity.
Asunto(s)
Adenocarcinoma/tratamiento farmacológico , Protocolos de Quimioterapia Combinada Antineoplásica/administración & dosificación , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Camptotecina/análogos & derivados , Neoplasias Colorrectales/tratamiento farmacológico , Terapia Recuperativa , Neoplasias Gástricas/tratamiento farmacológico , Adenocarcinoma/mortalidad , Adenocarcinoma/patología , Adulto , Anciano , Camptotecina/administración & dosificación , Camptotecina/efectos adversos , Distribución de Chi-Cuadrado , Neoplasias Colorrectales/mortalidad , Neoplasias Colorrectales/patología , Relación Dosis-Respuesta a Droga , Esquema de Medicación , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos , Femenino , Fluorouracilo/administración & dosificación , Fluorouracilo/efectos adversos , Estudios de Seguimiento , Humanos , Irinotecán , Masculino , Dosis Máxima Tolerada , Persona de Mediana Edad , Mitomicina/administración & dosificación , Mitomicina/efectos adversos , Estadificación de Neoplasias , Oportunidad Relativa , Probabilidad , Medición de Riesgo , Neoplasias Gástricas/mortalidad , Neoplasias Gástricas/patología , Análisis de SupervivenciaRESUMEN
Waldenstrom's macroglobulinemia (WM) is in the World Health Organization (WHO) classification considered to be a clinical syndrome rather than a specific pathologic diagnosis. The clinical manifestations associated with WM relate to direct tumor infiltration, hyperviscosity, and deposition of IgM in various tissues. The indications for and choice of treatment vary considerably and no generally accepted prognostic models exist. The clinical features, treatment, and prognosis of 72 patients with WM seen at one British (n = 36) and one Swedish (n = 36) academic center were therefore compared. Significantly more patients presented with a low albumin concentration (< v > 40 g/L, P <.001), anemia (hemoglobin < v > 120 g/L; P <.001), thrombocytopenia (< v > 150 x 10(9)/L; P <.05), hepatomegaly (P <.001), splenomegaly (P <.01), and lymphadenopathy (P <.01), at St Bartholomew's Hospital (SBH) in comparison to the Karolinska Hospital (KH). Fifty-six percent of SBH patients received chemotherapy immediately following diagnosis as compared to 14% at KH. The median overall survival of all patients was 6.3 years; 4.2 years and 11.0 years at SBH and KH, respectively (P <.001). In univariate analysis, anemia (hemoglobin < 120 g/L) and albumin < 35 g/L (but not <40 g/L) at diagnosis predicted a worse overall survival. The presence of hepatomegaly and/or splenomegaly and/or lymphadenopathy was significantly associated with anemia (P <.001) and hypoalbuminaemia (P <.001). The mean Morel score (including age, albumin, and cytopenias) of patients treated at SBH (2.6) was significantly higher than that of KH patients (1.6; P <.001). These findings illustrate the clinical heterogeneity of WM, most probably explained by differences in referral patterns, and in addition, indicate the need for establishing standard criteria for diagnosis, response to treatment, and prognostic features.
Asunto(s)
Macroglobulinemia de Waldenström/diagnóstico , Macroglobulinemia de Waldenström/terapia , Adulto , Anciano , Antineoplásicos/uso terapéutico , Femenino , Humanos , Masculino , Persona de Mediana Edad , Plasmaféresis , Pronóstico , Análisis de Supervivencia , Resultado del Tratamiento , Macroglobulinemia de Waldenström/mortalidadRESUMEN
A total of 29 previously untreated patients with histologically proven malignant pleural mesothelioma, with an ECOG score of < or = 2 and UICC stage I-II disease, were enrolled between May 1994 and October 1996. On days 1 and 2, 18 x 10(6) IU/day of rIL-2 was administered by continuous intravenous infusion, and 6 x 10(6) IU/day of rIL-2 by subcutaneous injection on days 5--20 inclusive of a 42-day cycle. Further treatment was administered if no radiological disease progression was demonstrated. A total of 29 patients were assessable for toxicity and 25 for response, and 49 cycles of IL-2 were administered with a median of one per patient (range, < 1-4). Toxicity included mild fever, nausea and vomiting, and skin rashes, < grade II. Three patients failed to complete one cycle of treatment because of toxicity and one died of disease before response evaluation. Two patients achieved a partial response (8%, 95% CI 1-26%) surviving 18.1 and 18.7 months from diagnosis. A total of 11 patients (44%, 95% CI 24-65%) with stable disease had a median survival of 13.6 months (range 6.5-33.8). The median survival was 8.6 months (range 3.7-34.5) for the 12 patients with progressive disease (48%, 95% CI 28-69%). This regimen of rIL-2 is well tolerated and shows limited activity in mesothelioma.
Asunto(s)
Interleucina-2/administración & dosificación , Mesotelioma/tratamiento farmacológico , Neoplasias Pleurales/tratamiento farmacológico , Adolescente , Adulto , Anciano , Progresión de la Enfermedad , Femenino , Humanos , Infusiones Intravenosas , Inyecciones Subcutáneas , Interleucina-2/efectos adversos , Interleucina-2/uso terapéutico , Masculino , Mesotelioma/patología , Persona de Mediana Edad , Neoplasias Pleurales/patología , Análisis de Supervivencia , Resultado del TratamientoRESUMEN
The need for dependable prognostic markers in colorectal cancer, both in the advanced as well the as adjuvant setting, is greater than ever. The introduction of new chemotherapeutic agents in the clinic, with different mechanisms of action as well as different side-effect profiles, has made this even more important. Angiogenesis, the formation of new vessels, is essential for tumour growth and metastasis. The adverse impact of tumour angiogenesis in the context of colorectal cancer on relapse and prognosis has been evaluated in numerous retrospective studies. Most of these studies have tended to be relatively small in terms of patient numbers and sometimes have reached conflicting conclusions. A number of different angiogenic factors, including vascular endothelial growth factor (VEGF), thymidine phosphorylase (TP) and intratumoural microvessel density (IMD), have been assessed to varying extents. This article highlights some of the important developments in this rapidly expanding field.
Asunto(s)
Neoplasias Colorrectales/irrigación sanguínea , Neovascularización Patológica/metabolismo , Factores de Crecimiento Endotelial/metabolismo , Factor 2 de Crecimiento de Fibroblastos/metabolismo , Humanos , Linfocinas/metabolismo , Neovascularización Patológica/patología , Pronóstico , Timidina Fosforilasa/metabolismo , Factor A de Crecimiento Endotelial Vascular , Factores de Crecimiento Endotelial VascularRESUMEN
PURPOSE: In a previous study of treatment for advanced colorectal cancer, the LV5FU2 regimen, comprising leucovorin (LV) plus bolus and infusional fluorouracil (5FU) every 2 weeks, was superior to the standard North Central Cancer Treatment Group/Mayo Clinic 5-day bolus 5FU/LV regimen. This phase III study investigated the effect of combining oxaliplatin with LV5FU2, with progression-free survival as the primary end point. PATIENTS AND METHODS: Four hundred twenty previously untreated patients with measurable disease were randomized to receive a 2-hour infusion of LV (200 mg/m(2)/d) followed by a 5FU bolus (400 mg/m(2)/d) and 22-hour infusion (600 mg/m(2)/d) for 2 consecutive days every 2 weeks, either alone or together with oxaliplatin 85 mg/m(2) as a 2-hour infusion on day 1. RESULTS: Patients allocated to oxaliplatin plus LV5FU2 had significantly longer progression-free survival (median, 9.0 v 6.2 months; P =.0003) and better response rate (50.7% v 22.3%; P =.0001) when compared with the control arm. The improvement in overall survival did not reach significance (median, 16.2 v 14.7 months; P =. 12). LV5FU2 plus oxaliplatin gave higher frequencies of National Cancer Institute common toxicity criteria grade 3/4 neutropenia (41. 7% v 5.3% of patients), grade 3/4 diarrhea (11.9% v 5.3%), and grade 3 neurosensory toxicity (18.2% v 0%), but this did not result in impairment of quality of life (QoL). Survival without disease progression or deterioration in global health status was longer in patients allocated to oxaliplatin treatment (P =.004). CONCLUSION: The LV5FU2-oxaliplatin combination seems beneficial as first-line therapy in advanced colorectal cancer, demonstrating a prolonged progression-free survival with acceptable tolerability and maintenance of QoL.
Asunto(s)
Adenocarcinoma/tratamiento farmacológico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Neoplasias Colorrectales/tratamiento farmacológico , Compuestos Organoplatinos/uso terapéutico , Adenocarcinoma/mortalidad , Adenocarcinoma/secundario , Adolescente , Adulto , Anciano , Neoplasias Colorrectales/mortalidad , Neoplasias Colorrectales/secundario , Diarrea/inducido químicamente , Supervivencia sin Enfermedad , Femenino , Fluorouracilo/administración & dosificación , Humanos , Leucovorina/administración & dosificación , Masculino , Persona de Mediana Edad , Análisis Multivariante , Neutropenia/inducido químicamente , Compuestos Organoplatinos/administración & dosificación , Oxaliplatino , Estudios Prospectivos , Calidad de Vida , Trastornos de la Sensación/inducido químicamente , Estadísticas no Paramétricas , Resultado del TratamientoRESUMEN
The combination of 5-fluorouracil (5-FU) and leucovorin has been the unofficial "standard" therapy for patients with colorectal cancer for over a decade. Recently, however, a number of new agents targeted against the enzyme thymidylate synthase have been synthesized and are in various stages of development. The currently available thymidylate synthase inhibitors are discussed. Enormous efforts have been made over the years to improve the efficacy of 5-FU, the most popular of these agents. Biochemical modulation by leucovorin has been the most successful so far. Continuous infusion schedules also appear to be advantageous over bolus administration. However, marked intra- and interpatient variability, combined with nonlinear elimination kinetics and erratic oral bioavailability are relative limitations to further development of 5-FU. New oral 5-FU prodrugs such as UFT, S-1, and Capecitabine may help to overcome some of these difficulties. Eniluracil, a potent inhibitor of the enzyme dihydropyrimidine dehydrogenase, may also help by overcoming potential 5-FU resistance mechanisms, in addition to increasing its bioavailability. Of the antifolate-based inhibitors, Tomudex is in the most advanced stage of development. Similar efficacy with 5-FU and a convenient schedule may suggest a role in future combination regimens. It is quite likely that even the most optimal thymidylate synthase inhibition will have limitations in terms of clinical efficacy. Novel combinations of 5-FU or its analogs with agents that have different mechanisms of action (e.g., oxaliplatin, irinotecan) could provide important new opportunities for improving the outlook of patients with colorectal cancer.