[Incidence and trends of neuroblastoma in Mexican children attending at Instituto Mexicano del Seguro Social]. / Incidencia y tendencia del neuroblastoma en niños derechohabientes del IMSS.

BACKGROUND: Neuroblastoma (NB) is the principal tumor of the sympathetic nervous system in children. OBJECTIVE: to describe the epidemiological and clinical characteristics of Mexican children with NB. METHODS: A population-based, prolective study, with data obtained from the Childhood Cancer Registry of the Instituto Mexicano del Seguro Social. The frequencies and incidence of the variables of the study were obtained by age and sex. The trend was calculated with the annual percentage of change. RESULTS: Of a total of 2758 children with cancer, 72 (2.6%) were identified in the Group IV, according to the International Classification of Childhood Cancer. The average incidence for NB was 3.8, the highest incidence was found in Guerrero. NB was highest in the group under one year of age (18.5). The male/female ratio was 1.1 and there was no trend toward an increase. Stages III and IV were presented in 88% of the cases. There was no association between the stages, the age at the TD, or the histological pattern. CONCLUSIONS: It is possible that the low incidence of NB in Mexican children is due to the difficulty in early diagnosis due the majority of the cases was diagnosed in the advanced stages.

Epidemiological and some clinical characteristics of neuroblastoma in Mexican children (1996-2005).

BACKGROUND: Neuroblastoma (NB) is the principal tumor of the sympathetic nervous system in children under one year of age. The incidence in developed countries is greater than that in developing countries. The aim of this article is to present the epidemiological and some clinical characteristics of Mexican children with NB. METHODS: A population-based, prolective study, with data obtained from the Childhood Cancer Registry of the Instituto Mexicano de Seguro Social. STATISTICAL ANALYSIS: The simple frequencies of the variables of the study and the annual average incidence (per 1,000,000 children/years) by age and sex were obtained. The trend was evaluated by calculating the annual percentage of change. The curves of Kaplan-Meyer were employed for the survival rate and the log-rank test was used to compare the curves. RESULTS: Of a total of 2,758 children with cancer registered during the period from 1996-2005, 72 (2.6%) were identified as having Group IV, defined according to the International Classification of Childhood Cancer. The incidence for NB was 3.8 per 1,000,000 children/year; NB was highest in the group of children under one year of age, followed by the group of children between the ages 1-4 years (18.5 and 5.4 per 1,000,000 children/years, respectively). The male/female ratio was 1.1 and there was no trend toward an increase. The time of diagnosis was 26 days (median), but varied according to the stage at diagnosis. Stages III and IV were presented in 88% of the cases. There was no association between the stage, the age at time of diagnosis, or the histological pattern. The overall five-year survival rate was 64%; the patients with stage I, II, III, or IVs did not die; and the five-year survival rate of cases in Stage IV was 40%. CONCLUSION: It is possible that the low incidence of neuroblastoma in Mexican children is due to the difficulty in diagnosing the cases with the best prognosis, some of which could have had spontaneous regression. There was no trend to an increase; the majority of the cases were diagnosed in the advanced stages; and the overall five-years survival rate was similar to that for developed countries.

[Cancer epidemiology in adolescents of 15 and 16-year-old]. / Epidemiología del cáncer en adolescentes de 15 y 16 años.

OBJECTIVE: to present the frequency of different types of cancer in adolescents with 15 and 16-year-old treated at the Instituto Mexicano del Seguro Social (IMSS) in Mexico City (MC) hospitals. METHODS: it was an observational and prolective study. During January 1 of 1996 to December 31 of 2005, were analyzed new cases of adolescents of 15 and 16-year-old with malignant neoplasms in adolescents at IMSS. The neo-plasms were grouped according with the International Classification of Childhood Cancer; they were stratified by age, sex, and place of residence, and the frequency of these variables were obtained. RESULTS: a total of 207 cases were registered. Leukemias were more frequent with 55 cases (26.6%); the second place was for bone tumors with 36 cases (17.4%) and the third place were lymphomas with 32 cases (15.5%). There were not cases of retinoblastoma and renal tumors; only 8 cases of carcinomas (3.9%) were registered. The greatest frequency was observed in males with 116 cases (56.0%), with male/female ratio of 1.3:1. Mexico City and State of Mexico were more frequent places of residence with 70.5% of cases. Near of forty nine percent of cases (48.8%) with solid tumors were diagnosed in III or IV stages. CONCLUSIONS: the pattern of cancer was different from older adolescents (15 to 19-year-old), it is necessary to conduct studies of survey in order to determine epidemiology of cancer in the Mexican adolescents.

Incidence of cancer in children residing in ten jurisdictions of the Mexican Republic: importance of the Cancer registry (a population-based study).

BACKGROUND: In 1996, Mexico started to register cases of childhood cancer. Here, we describe the incidence of cancer in children, residing in ten Mexican jurisdictions, who were treated by the Instituto Mexicano del Seguro Social (IMSS). METHODS: New cases of childhood cancer, which were registered prospectively in nine principal Medical Centers of IMSS during the periods 1998-2000 (five jurisdictions) and 1996-2002 (five jurisdictions), were analyzed. Personnel were specifically trained to register, capture, and encode information. For each of these jurisdictions, the frequency, average annual age-standardized incidence (AAS) and average annual incidence per period by sex and, age, were calculated (rates per 1,000,000 children/years). RESULTS: In total 2,615 new cases of cancer were registered, with the male/female ratio generally >1, but in some tumors there were more cases in females (retinoblastoma, germ cells tumors). The principal groups of neoplasms in seven jurisdictions were leukemias, central nervous system tumors (CNS tumors), and lymphomas, and the combined frequency for these three groups was 62.6 to 77.2%. Most frequently found (five jurisdictions) was the North American-European pattern (leukemias-CNS tumors-lymphomas). Eight jurisdictions had AAS within the range reported in the world literature. The highest incidence was found for children underless than five year of age. In eight jurisdictions, leukemia had high incidence (>50). The AAS of lymphomas was between 1.9 to 28.6. Chiapas and Guerrero had the highest AAS of CNS tumors (31.9 and 30.3, respectively). The frequency and incidence of neuroblastoma was low. Chiapas had the highest incidence of retinoblastoma (21.8). Germ-cell tumors had high incidence. CONCLUSION: The North American-European pattern of cancers was the principal one found; the overall incidence was within the range reported worldwide. In general but particularly in two jurisdictions (Yucatán and Chiapas), it will be necessary to carry out studies concerning the causes of cancer in children. Due to the little that is known about the incidence of cancer in Mexican children, it will be necessary to develop a national program to establish a cancer registry for the whole of the country.

[General and specific incidence of cancer among children affiliated to the Mexican Institute of Social Security]. / Incidencia general y específica de cáncer en niños derechohabientes del IMSS.

OBJECTIVE: To determine the epidemiology of cancer among children from eleven Mexican states affiliated to Mexican Social Security Institute (Instituto Mexicano del Seguro Social, IMSS). METHODS: 2663 Cases of children with cancer were prospectively registered between 1996 and 2002 in the main IMSS medical centers. The cases were classified according to the International Classification for Childhood Cancer. The general and specific cancer incidences (rate per million children/year, age standardized) were obtained. RESULTS: The principal groups of cancer in nine states were leukemias, lymphomas and central nervous system tumors (CNST). In eight states, the incidence was similar than reported worldwide (100 to 180); Chiapas had the highest incidence (203.5). Leukemias had higher incidence in seven States (>50). The highest incidences of CNST were observed in Chiapas and Guerrero (31.9 and 30.3); The incidence of neuroblastoma was low. Chiapas showed the highest incidence of retinoblastoma, bone tumors and carcinomas (21.8, 12.2 and 5.9 respectively); Puebla had the highest incidence of liver tumors (11.3) in which stages III and IV were the most frequent (67.8 %). CONCLUSIONS: The main groups of cancer in Mexican children were leukemias, CNST, and lymphomas. Some states had high incidence; more than 50 % of children with solid tumors were diagnosed in advanced stages.

Cytogenetic studies in children with Down syndrome and acute leukemia.

The frequency of chromosomal alterations was compared among four children groups: those with Down syndrome and acute leukemia (DS/AL), those with acute leukemia (AL), those with only Down syndrome (DS) and healthy children (NC). The frequency of acquired chromosome abnormalities was larger in the AL group, followed by the DS/AL. The gaps and isogaps were more frequent in children with only DS. The polymorphisms of the constitutive heterochromatin were larger in the DS/AL group. These findings appear to imply that more genetic changes are necessary to develop AL in the case of healthy children compared to children with DS.

Traslocación 5;15 familiar asociada al síndrome de Prader Willi / 5;15 familial translocation associate to prader-willi syndrome

El síndrome de Prader-Willi se caracteriza por hipotonía muscular, talla baja, obesidad, infantilismo sexual y retardo mental; se ha reconocido heterogeneidad genética. Se presenta un paciente de seis años de edad con estas características clínicas y con deleción 15q13--pter por translocación 5/15 familiar. Se discuten aspectos clínicos, cromosómicos y de asesoramiento genético.

Disgenesia gonadal 46,XX con ausencia de cromatina X en citología gonadal / Gonadal dysgenesis 46,XX with abscense of chromatin X in gonadal cytology

Se presenta el caso de 21 años de edad con fenotipo femenino, quien consultó por amenorrea secundaria y presentaba ligero desarrollo mamario y de vello púbico. El estudio hormonal reveló hipoestrenismo e hipegonadotropismo. En la laparoscopía se encontraron cintillas gonadales. Aunque el cariotipo practicado en linfocitos de sangre periférica resultó normal 46,XX, se encontró disparidad en los estudios citogenéticos de la cromatina X, la cual fue positiva en la mucosa oral negativa en el tejido gonadal. Se enfatiza el hecho de que algunas pacientes con disgenesia gonadal y cariotipo 46,XX pueden corresponder a mosaicismos cromasómicos, los cuales no se detectan generalmente porque no se realizan estudios de cariotipo en otros tejidos, sobre todo en el esbozo de tejido gonadal.

Biopsia ovárica translaparoscópica con estudio de cromatina sexual en falla ovárica prematura / Translaparoscopic ovarian biopsy with chromatin study in premature ovarian failure

Se realizó biopsia de ovario translaparoscópica en 17 pacientes con falla ovárica prematura (FOP), de junio de 1986 a junio de 1988, la edad de las pacientes varió de 17 a 35 años, el diagnóstico se hizo en base a la presencia de amenorrea acompañada de hipoestrogenismo hipergonadotrópico. Se practicó cariotipo de 12 pacientes y se detectaron dos casos de mosaicismo : 46XX/45XO y 46Xi/45XO. El resultado anatomopatológico de la biopsia de ovario mostró: 14 casos con estroma ovárico predominante sin folículos, un caso con tejido conjuntivo y fibrosis predominante sin folículos y un caso con tejido ovárico con 20 folículos primarios. La cromatina sexual en gónada se realizó en cinco pacientes, encontrándose dos casos negativos, uno de ellos con cariotipo 46XX y el otro con mosaico 46Xi/45XO. Es posible que la gónada tenga en algunos casos de FOP una línea celular anómala diferente a la somática, siendo la responsable de la no viabilidad del aparato folicular. En vista de lo anterior, este estudio muestra el valor de la biopsia de ovario, con estudio genético de cromatina sexual en gónada en los casos de FOP, para precisar su etiología, pronóstico y su posible tratamiento.