A multicentre report from the Mexican Retinoblastoma Group.

BACKGROUND: Retinoblastoma (RB) is a relatively uncommon tumour in childhood. The incidence of retinoblastoma in Mexico is probably higher than the incidence reported worldwide, however there is not enough information about the characteristics of this illness in Mexico. This report aims to present the results of a multicentre clinical survey of RB in Mexico. METHODS: A retrospective study was carried out on all RB cases treated in 16 institutions during the last six years. The variables analysed were age at diagnosis, sex, affected eyes, treatment modalities, and pathological staging. Overall survival was obtained. RESULTS: The authors analysed 500 cases; age range was 0-182 months. There were 364 unilateral cases (72.8%). Enucleation was performed in 84.9% of the patients. The St Jude's staging was: 7.4% stage I, 52.8% stage II, 18.0% stage III, 11.4% stage IV, 7.2% not evaluated, and 3.2% missing data. Chemotherapy was used in 74.4% of the patients. Disease free survival was 89% at 73 months follow up. CONCLUSIONS: The paper presents a great number of cases and pioneers multicentre studies in paediatric ophthalmology and oncology in this country. Given the great number of patients in advanced stages and the variability on treatment schemes, it is evident that it is mandatory to work in a cooperative group and develop a national early detection programme as well as a treatment protocol which include all specialists involved in the care of patients with RB.

B-lineage acute lymphoblastic leukemia of childhood. An institutional experience.

A total of 119 children (1990-95) with acute lymphoblastic leukemia (ALL) B-lineage either CD10+ or CD10- were registered into a single non-randomized chemotherapy protocol. Only untreated patients with standard risk were included in the study. Their ages ranged from 1.8-10 years with a mean of 5.1 years. There were 82 (68%) children with early pre B-All, 35 (29%) with pre B-ALL and 2(1.6%) with transitional pre B-ALL (p < 0.00001). The patients were divided according to CD10 reactivity, either + (94 children) or -(25 patients). The event-free survival (EFS) at 60 months for the CD10+ children was of 78% (alive 73/94), while for the CD10- was 71% (alive 18/25) (p = 0.6) and 74% for both groups. The factors that influenced favorably the survival in the CD10+ group were the age between 3 to 5.99 years (p < 0.00001), sex (either male or female), leukocyte count between 10-24.9 x 10(9)/l (p < 0.00001), LDH under 300 U/I (p < 0.00001) and L1 bone marrow cytomorphology (p < 0.00001). In the CD10- patients, the EFS was favorably influenced by the female sex (p = 0.04), leukocyte count under 10 x 10(9)/l (p = 0.05) and LDH < 300 U/l (p = 0.02). CNS infiltration was documented in 4.2% (5/119). Mortality secondary to chemotherapy was seen in 7%. In conclusion, this is the first large series in Mexican children with B-lineage ALL published. Because of the relatively small number of patients in each group (pre B and transitional pre B), all the patients in the current series were treated alike. When the 119 patients were divided only on the basis of CD10 reactivity, the EFS for both groups (CD10+ and-) was similar; therefore, the reactivity to CD10 has no prognostic value in this type of ALL.

Arsenic-cadmium interaction in rats.

Simultaneous exposure to cadmium and arsenic is highly probable in the urban area of San Luis Potosi, Mexico due to common localization of copper and zinc smelters. Therefore, in this work, rats were intraperitoneally exposed either to cadmium or arsenic alone, or simultaneously to both metals. The effects of these treatments on three different toxicological parameters were studied. Cadmium modified the LD50 of arsenic and conversely arsenic modified the LD50 for cadmium. At the histopathological level, arsenic appeared to protect against the cadmium effects, especially on testes. This protective effect seemed to be related to the glutathione levels found in this tissue: rats exposed to both arsenic and cadmium, presented glutathione values intermediate to those observed after exposure to either metal alone; arsenic had the highest value and cadmium the lowest. In liver, rats exposed to arsenic, cadmium or arsenic and cadmium, presented glutathione values below those in the saline group, with the lowest value corresponding to the arsenic and cadmium treatment. The results appear to support the proposed interaction between arsenic and cadmium and coexposure to both metals seems to alter certain effects produced by either metal alone.