Un método para individualizar el riesgo de una errónea clasificación ganglionar negativa en el cáncer de colon / A method for individualising the risk of a negative lymph node classification error in cancer of the colon

Introducción y objetivos: En el cáncer de colon, el número de ganglios linfáticos que se deberían analizar antes de clasificar a un paciente como libre de afectación ganglionar ha sido ampliamente discutido. Se propone un modelo matemático basado en el teorema de Bayes para calcular la probabilidad de error (PE) similar al utilizado habitualmente para la evaluación de una prueba diagnóstica pero adaptado a una variable cuantitativa como es un recuento ganglionar. Métodos: Se revisaron las historias clínicas de 480 pacientes intervenidos de forma programada de cáncer de colon con intención curativa, excluyendo los casos que presentaban metástasis de cualquier tipo. Con el fin de calcular las PE, para la serie completa y para diversos subgrupos de pacientes (tumores T2, T3, y T4) se aplicó la fórmula que proponemos basada en dicho teorema de Bayes. Resultados: Para las probabilidades de error al clasificar un paciente como N negativo que oscilaran entre un 5% hasta un 1‰ (próximo o prácticamente 0), la mínima cifra de ganglios negativos necesarios para analizar fluctuó entre 7 y 17 respectivamente para la serie completa. Esta cifra mínima también fue cambiante para los diversos subgrupos (tumores T2, T3, y T4) considerados. Fundamentalmente, tales cifras dependen de las características de la casuística de un grupo de trabajo concreto en cuanto a prevalencia de casos N+ que manejen, y de su capacidad históricamente demostrada para recolectar e identificar ganglios positivos en los pacientes que los presentaran. Conclusión: Desde el punto de vista matemático, el número mínimo de ganglios que se deberían analizar en el cáncer de colon para clasificar a un paciente como N negativo no es una constante. Este depende del error que se esté dispuesto a asumir para tal diagnóstico, puede estar en función de ciertos rasgos del tumor, y además, se debería adaptar a la casuística de cada grupo de trabajo (AU)

Introduction: In cancer of the colon, the number of lymph nodes that should be analysed before a patient is classified as free of lymph node involvement has been widely discussed. A mathematical model is proposed which is based on the Bayes Theorem for calculating the probality of error (PE) similar to that normally used to evaluate a diagnostic test, but adapted to a quantitative variable, the lymph node count. Methods: The clinical histories of 480 patients routinely operated on in attempt to cure cancer of the colon were reviewed. Cases with any kind of mesttasis were excluded. The proposed formula based on the Bayes Theorem was applied with the aim of calculating the PEs for the complete series and for different patient sub-groups (T2, T3, and T4 tumours). Results: For the probabilities of error of classifying a patient as N negative, which varied between 5% and 1% (near or practically 0), the minimum number of negative lymph nodes required for analysis fluctuated between 7 and 17, respectively, for the complete series. This minimum figure was also variable for the different sub-groups (T2, T3, and T4 tumours) studied. These numbers mainly depended on the case characteristics of a specific study group as regards the prevalence of the N+ cases that they dealt with, and of its historically demonstrated ability to collect and identify positive lymph nodes in those patients that had them. Conclusion: From a mathematical point of view, the minimum number of lymph nodes that have to be analysed in cancer of the colon in order to classify a patient as N negative is not a constant. This depends on the error that is prepared to be assumed for that diagnosis, possibly depending on certain tumour traits, and also may be adapted to the cases of each study group (AU)

[A method for individualising the risk of a negative lymph node classification error in cancer of the colon]. / Un método para individualizar el riesgo de una errónea clasificación ganglionar negativa en el cáncer de colon.

INTRODUCTION: In cancer of the colon, the number of lymph nodes that should be analysed before a patient is classified as free of lymph node involvement has been widely discussed. A mathematical model is proposed which is based on the Bayes Theorem for calculating the probability of error (PE) similar to that normally used to evaluate a diagnostic test, but adapted to a quantitative variable, the lymph node count. METHODS: The clinical histories of 480 patients routinely operated on in attempt to cure cancer of the colon were reviewed. Cases with any kind of metastasis were excluded. The proposed formula based on the Bayes Theorem was applied with the aim of calculating the PEs for the complete series and for different patient sub-groups (T2, T3, and T4 tumours). RESULTS: For the probabilities of error of classifying a patient as N negative, which varied between 5% and 1% (near or practically 0), the minimum number of negative lymph nodes required for analysis fluctuated between 7 and 17, respectively, for the complete series. This minimum figure was also variable for the different sub-groups (T2, T3, and T4 tumours) studied. These numbers mainly depended on the case characteristics of a specific study group as regards the prevalence of the N+ cases that they dealt with, and of its historically demonstrated ability to collect and identify positive lymph nodes in those patients that had them. CONCLUSION: From a mathematical point of view, the minimum number of lymph nodes that have to be analysed in cancer of the colon in order to classify a patient as N negative is not a constant. This depends on the error that is prepared to be assumed for that diagnosis, possibly depending on certain tumour traits, and also may be adapted to the cases of each study group.

Treatment of morbid obesity and hiatal paraesophageal hernia by laparoscopic Roux-en-Y gastric bypass.

Obesity has been proven to be a significant independent risk factor for hiatal hernia. In morbidly obese patients, the usual techniques to improve gastroesophageal reflux after hiatal hernia repair could have poorer outcomes than in the general population. Laparoscopic Roux-en-Y gastric bypass (LRYGBP) has been demonstrated to be an effective procedure in controlling symptoms and complications of gastroesophageal reflux in these patients. Therefore, LRYGBP is one of the most frequent procedures performed in bariatric surgery. The authors report a case of a 41-year-old man with a body mass index (BMI) of 44.6 kg/m(2) who was diagnosed with giant type III hiatal hernia. A laparoscopic approach for both hiatal hernia repair and LRYGBP was performed. At 6 months follow-up, the patient has lost 30% of excess body weight (BMI 34.4), and there is no evidence of recurrence of the esophageal hernia.

[Recommendations for the clinical evaluation of results in the biomedical literature]. / Recomendaciones para la valoración clínica de los resultados en literatura biomédica.

The assessment and interpretation of the results of a clinical study are a real challenge for the clinicians. In this paper we establish a general basis for a critical and reserved assessment of these, from the fundamental aspects of the design and statistics, as well as the application of the results to our own patients according to risk and benefit criteria. Main errors and the traps that should be avoided are emphasised.

Recomendaciones para la valoración clínica de los resultados en literatura biomédica / Recommendations for the clinical evaluation of results in the biomedical literature

La valoración y la interpretación de los resultados de un estudio clínico son un auténtico reto para el profesional médico. En el presente artículo se ofrecen las bases generales para una valoración crítica y comedida, partiendo de aspectos fundamentales del diseño y de la estadística, así como de la aplicación de los resultados a nuestros propios pacientes según criterios de riesgo y beneficio. Se hace hincapié en los principales errores y en las trampas que se debe evitar (AU)

The assessment and interpretation of the results of a clinical study are a real challenge for the clinicians. In this paper we establish a general basis for a critical and reserved assessment of these, from the fundamental aspects of the design and statistics, as well as the application of the results to our own patients according to risk and benefit criteria. Main errors and the traps that should be avoided are emphasized (AU)

[Brucella spp orchiepididymitis]. / Orquiepididimitis por Brucella spp.

OBJECTIVE: To report a brucellar orchiepididymitis case and to review the diagnosis and treatment of this pathology. METHOD: We present the case of a 62 year old man presenting with fever, testicular pain and constitutional syndrome. The diagnosis was made after ultrasound, blood cultures and anamnesis. RESULTS: The treatment was Doxiciclin six weeks and teicoplanin, the second one was replaced with ciprofloxacin. CONCLUSION: It is important to make a correct anamnesis to the patient with orchiepididymitis to identify any risk factor for brucellosis. The diagnosis is confirmed with blood cultures. The oral antibiotics are enough to cure patients.

[Is there a minimum number of lymph nodes that should be examined after surgical resection of colorectal cancer?]. / ¿Existe un número mínimo de ganglios linfáticos que se debe analizar en la cirugía del cáncer colorrectal?

Metastasis to regional lymph nodes, after distant metastasis, is the most important prognostic factor of colorectal carcinomas. It is also of primary importance in decisions related to the administration of adjuvant treatments. Most scientific associations recommend the examination of at least 12 lymph nodes for the reliable determination of the absence of nodal metastases. We performed a literature review on lymph node recovery in order to determine whether 12 is the minimum and optimal number of lymph nodes to be examined after colorrectal cancer surgery. The differences between authors suggest that an optimal number of lymph nodes to be examined after colorectal cancer surgery probably does not exist and depends on many factors. Thus, recovering as many lymph nodes as possible seems to be a good option.

¿Existe un número mínimo de ganglios linfáticos que se debe analizar en la cirugía del cáncer colorrectal? / Is there a minimum number of lymph nodes that should be examined after surgical resection of colorectal cancer?

La afección ganglionar es, después de la metástasis a distancia, el principal factor pronóstico en los pacientes con cáncer colorrectal. Además, condiciona la necesidad de tratamientos adyuvantes. Para determinar que un paciente se encuentra libre de enfermedad ganglionar, la mayoría de las asociaciones recomiendan analizar, al menos, 12 ganglios linfáticos. Se planteó en este trabajo la revisión de la literatura sobre el tema para valorar si 12 es el número mínimo y óptimo de ganglios que se debe analizar. La disparidad de resultados encontrados en la mayoría de los trabajos científicos orienta a que, probablemente, no haya un número óptimo de ganglios linfáticos que se debe analizar, sino que estará condicionado por múltiples factores. Por ello, obtener la mayor cantidad posible de ganglios parece una buena alternative (AU)

Metastasis to regional lymph nodes, after distant metastasis, is the most important prognostic factor of colorectal carcinomas. It is also of primary importance in decisions related to the administration of adjuvant treatments. Most scientific associations recommend the examination of at least 12 lymph nodes for the reliable determination of the absence of nodal metastases. We performed a literature review on lymph node recovery in order to determine whether 12 is the minimum and optimal number of lymph nodes to be examined after colorrectal cancer surgery. The differences between authors suggest that an optimal number of lymph nodes to be examined after colorectal cancer surgery probably does not exist and depends on many factors. Thus, recovering as many lymph nodes as possible seems to be a good option (AU)

[Confidence intervals: why use them?]. / Intervalos de confianza: por qué usarlos.

We analyze the reasons why the use of confidence intervals is highly advisable. Among these reasons, confidence intervals provide an approach to knowledge of the real importance of a result, independently of statistical significance, as well as equivalence assessment between two variables.

Intervalos de confianza: por qué usarlos / Confidence intervals: why use them?

Se analizan las razones por las que el uso de los intervalos de confianza es altamente recomendable. Entre estas razones, destacan la aproximación al conocimiento de la importancia real de un resultado, independientemente de la significación estadística, y la valoración de equivalencia entre dos variables (AU)

We analyze the reasons why the use of confidence intervals is highly advisable. Among these reasons, confidence intervals provide an approach to knowledge of the real importance of a result, independently of statistical significance, as well as equivalence assessment between two variables (AU)