Armando Martínez-Avalos

Childhood acute leukemias are frequent in Mexico City: descriptive epidemiology

BackgroundWorldwide, acute leukemia is the most common type of childhood cancer. It is particularly common in the Hispanic populations residing in the United States, Costa Rica, and Mexico City. The objective of this study was to determine the incidence of acute leukemia in children who were diagnosed and treated in public hospitals in Mexico City.MethodsIncluded in this study were those children, under 15 years of age and residents of Mexico City, who were diagnosed in 2006 and 2007 with leukemia, as determined by using the International Classification of Childhood Cancer. The average annual incidence rates (AAIR), and the standardized average annual incidence rates (SAAIR) per million children were calculated. We calculated crude, age- and sex-specific incidence rates and adjusted for age by the direct method with the world population as standard. We determined if there were a correlation between the incidence of acute leukemias in the various boroughs of Mexico City and either the number of agricultural hectares, the average number of persons per household, or the municipal human development index for Mexico (used as a reference of socio-economic level).ResultsAlthough a total of 610 new cases of leukemia were registered during 2006-2007, only 228 fit the criteria for inclusion in this study. The overall SAAIR was 57.6 per million children (95% CI, 46.9-68.3); acute lymphoblastic leukemia (ALL) was the most frequent type of leukemia, constituting 85.1% of the cases (SAAIR: 49.5 per million), followed by acute myeloblastic leukemia at 12.3% (SAAIR: 6.9 per million), and chronic myeloid leukemia at 1.7% (SAAIR: 0.9 per million). The 1-4 years age group had the highest SAAIR for ALL (77.7 per million). For cases of ALL, 73.2% had precursor B-cell immunophenotype (SAAIR: 35.8 per million) and 12.4% had T-cell immunophenotype (SAAIR 6.3 per million). The peak ages for ALL were 2-6 years and 8-10 years. More than half the children (58.8%) were classified as high risk. There was a positive correlation between the average number of persons per household and the incidence of the pre-B immunophenotype (Pearsons r, 0.789; P = 0.02).ConclusionsThe frequency of ALL in Mexico City is among the highest in the world, similar to those found for Hispanics in the United States and in Costa Rica.

Breastfeeding and early infection in the aetiology of childhood leukaemia in Down syndrome.

Background:For a child to develop acute leukaemia (AL), environmental exposure may not be sufficient: interaction with a susceptibility factor to the disease, such as Down syndrome (DS), may also be necessary. We assessed whether breastfeeding and early infection were associated with the risk of developing AL in children with DS.Methods:Children with DS in Mexico City, and either with or without AL, were the cases (N=57) and controls (N=218), respectively. Population was divided in children with AL and with acute lymphoblastic leukaemia (ALL) and also in children ⩽6 and >6 years old.Results:Breastfeeding and early infections showed moderate (but not significant) association for AL, whereas hospitalisation by infection during the first year of life increased the risk: odds ratios (confidence interval 95%) were 0.84 (0.43–1.61), 1.70 (0.82–3.52); and 3.57 (1.59–8.05), respectively. A similar result was obtained when only ALL was analysed.Conclusion:We found that breastfeeding was a protective factor for developing AL and ALL, and during the first year of life, infections requiring hospitalisation were related to a risk for developing the disease in those children with DS >6 years of age. These data do not support the Greavess hypothesis of early infection being protective for developing ALL.

Magnetic fields and acute leukemia in children with Down syndrome.

Background: We analyzed effects of exposure to magnetic fields on the expression of acute leukemia in children with Down syndrome (who have a 20-fold higher risk of leukemia). Methods: We performed a case–control study that included 42 children with both acute leukemia and Down syndrome as cases and 124 healthy children with Down syndrome as controls. We obtained demographic information concerning the children and took spot measurements of magnetic fields at each residence. Results: The odds ratio for direct measurements of magnetic fields ≥6.00 mG was 3.7 (95% confidence interval = 1.05–13.1). Conclusion: The association between magnetic fields and leukemia in children with Down syndrome suggests the possibility of a causal role for magnetic fields in the etiology of leukemia among a genetically susceptible subgroup of children.

Father's occupational exposure to carcinogenic agents and childhood acute leukemia: a new method to assess exposure (a case-control study)

BackgroundMedical research has not been able to establish whether a fathers occupational exposures are associated with the development of acute leukemia (AL) in their offspring. The studies conducted have weaknesses that have generated a misclassification of such exposure. Occupations and exposures to substances associated with childhood cancer are not very frequently encountered in the general population; thus, the reported risks are both inconsistent and inaccurate. In this study, to assess exposure we used a new method, an exposure index, which took into consideration the industrial branch, specific position, use of protective equipment, substances at work, degree of contact with such substances, and time of exposure. This index allowed us to obtain a grade, which permitted the identification of individuals according to their level of exposure to known or potentially carcinogenic agents that are not necessarily specifically identified as risk factors for leukemia. The aim of this study was to determine the association between a fathers occupational exposure to carcinogenic agents and the presence of AL in their offspring.MethodsFrom 1999 to 2000, a case-control study was performed with 193 children who reside in Mexico City and had been diagnosed with AL. The initial sample-size calculation was 150 children per group, assessed with an expected odds ratio (OR) of three and a minimum exposure frequency of 15.8%. These children were matched by age, sex, and institution with 193 pediatric surgical patients at secondary-care hospitals. A questionnaire was used to determine each childs background and the characteristics of the fathers occupation(s). In order to determine the level of exposure to carcinogenic agents, a previously validated exposure index (occupational exposure index, OEI) was used. The consistency and validity of the index were assessed by a questionnaire comparison, the sensory recognition of the work area, and an experts opinion.ResultsThe adjusted ORs and 95% confidence intervals (CI) were 1.69 (0.98, 2.92) during the preconception period; 1.98 (1.13, 3.45) during the index pregnancy; 2.11 (1.17, 3.78) during breastfeeding period; 2.17 (1.28, 3.66) after birth; and 2.06 (1.24, 3.42) for global exposure.ConclusionThis is the first study in which an OEI was used to assess a fathers occupational exposure to carcinogenic agents as a risk factor for the development of childhood AL in his offspring. From our results, we conclude that children whose fathers have been exposed to a high level of carcinogenic agents seem to have a greater risk of developing acute leukemia. However, confounding factors cannot be disregarded due to an incomplete control for confounding.

TOXICITY PREVENTION WITH AMIFOSTINE IN PEDIATRIC OSTEOSARCOMA PATIENTS TREATED WITH CISPLATIN AND DOXORUBICIN

Amifostine has emerged as a pancytoprotectant shown protection against nephrotoxicity, neurotoxicity and ototoxicity in preclinical studies. Methods: We designed a prospective comparative randomized trial to evaluate the cytoprotective effects of amifostine in patients with osteosarcoma receiving cisplatin and doxorrubicin. Patients were evaluated for renal, hearing and cardiac toxicity. Results: We included 28 patients, mean age was 11.6 years, five had metastatic disease. Fifteen patients received amifostine and 13 did not. 20% of patients receiving amifostine developed renal toxicity compared to 30% in the control group (p = 0.318). Grade 1 and 2 audiologic toxicity was present in 100% of the experimental group against 85% of the controls (p = 0.501). Grade 1 cardiac toxicity was present in 2 patients in the control group (p = 0.175). There were no statistical significant differences between the two groups for chemotherapy-related toxicity. Response to chemotherapy was significantly better in the amifostine group. Conclusion: amifostine did not reduce the ototoxicity and nephrotoxicity of our treatment regime. It was not well tolerated due to emesis. It is a selective cytoprotectant without reducing the effect of chemotherapy.

Allergy and acute leukaemia in children with Down syndrome: a population study. Report from the Mexican inter-institutional group for the identification of the causes of childhood leukaemia

Background:Allergies have been described as protective factors against the development of childhood acute leukaemia (AL). Our objective was to investigate the associations between allergy history and the development of AL and acute lymphoblastic leukaemia (ALL) in children with Down syndrome (DS).Methods:A case–control study was performed in Mexico City. The cases (n=97) were diagnosed at nine public hospitals, and the controls (n=222) were recruited at institutions for children with DS. Odds ratios (OR) were calculated.Results:Asthma was positively associated with AL development (OR=4.18; 95% confidence interval (CI): 1.47–11.87), whereas skin allergies were negatively associated (OR=0.42; 95% CI: 0.20–0.91).Conclusion:Our findings suggest that allergies and AL in children with DS share biological and immune mechanisms. To our knowledge, this is the first study reporting associations between allergies and AL in children with DS.

Improved treatment results in Mexican children with acute myeloid leukemia using a Medical Research Council (MRC)-acute myeloid leukemia 10 modified protocol

We analysed the results of three protocols from 1990 to 2005. Protocol I (1990–1996) consisted of a 2 year VAPA regime. Protocol II (1996–2003) on 1 year daunorubicin/cytarabine alternating with etoposide/cytarabine. Protocol III (2003–2005) on six cycles MRC AML 10 modified. Patients with de novo acute myeloid leukemia 0 to 18 years were included. Demographic and clinical characteristics were analysed. Patients with >100,000 leukocytes, M4 or M5 and primary CNS disease were considered high risk. We compared remission rate, overall and event-free survival. Descriptive statistics, chi square, Kaplan-Meier and long rank tests were used. One hundred forty-five patients were included, 46 in Protocol I; 60 in II and 39 in III. There were no differences in characteristics between groups, except for more low risk patients in Protocol II (61%vs. 43% and 41%. (p = 0.05). Remission rate for Protocol I was 52%, for II 50% and for III 92% (p = 0.0001). Relapse was 18, 30 and 35, respectively (p = 0.141). Five-year event-free survival was 17.9% ± 6.6%, 15.5% ± 4.1% and 43.5% ± 4.1% (s.e) (p = 0.0002). Five-year overall survival was 19.5% ± 8%, 17.2% ± 5.9% and 51.2% ± 4.1% (s.e) (p = 0.0002). The results were superior in the MRC-10 derived protocol.

Early death in children with acute lymphoblastic leukemia: does malnutrition play a role?

The study aim was to correlate malnutrition and early death in children with acute lymphoblastic leukemia (ALL). A study was conducted in 100 consecutive children with ALL. An analysis included clinical and laboratory parameters as well as co-morbidity factors. Forty patients were standard risk and 60 high risk. Multivariate analysis showed variables of statistical importance, including female gender (p 010), ALL high-risk (p 04), and infection (p 036). Malnutrition (p 1.0) and poverty (p 0.5) did not influence. Early mortality was documented in 15/100 (15%) patients. The study shows that high-risk ALL and infection represent the leading causes of early mortality.

Diagnosis of bone marrow metastases in children with solid tumors and lymphomas. Aspiration, or unilateral or bilateral biopsy?

BACKGROUND Malignancies are among the most common causes of death in children. The present study was undertaken to evaluate and compare bone marrow aspiration and unilateral biopsy to detect bone marrow metastases in pediatric patients, using bilateral biopsy as the gold standard. METHODS During a 6-month period, 63 consecutive newly diagnosed children with confirmed malignant diseases other than leukemia were evaluated for bone marrow metastases or infiltration. Biopsies were obtained from both right and left posterior iliac crests whereas aspiration was performed only at the right crest. Interpretation to the right-side biopsy was considered as the unilateral biopsy result, whereas the bilateral biopsy result was as follows: positively was accepted if one or both of the two-side samples were qualified as positive, while a negative result was considered only if both sides were negative. The bilateral biopsy was considered the gold standard, and sensitivity, specificity, positive and negative predictive value, and false positive and negative rates were computed for the unilateral biopsy and aspiration procedure. RESULTS We identified bone marrow metastases in 11 (17.5%) patients. The sensitivity was the only significant difference (p <0.05) observed between unilateral biopsy and aspiration. Finally, of the 63 patients, unilateral biopsy was reported as inadequate in one patient (1.6%), while aspiration was inadequate in two (3.2%). CONCLUSION Unilateral biopsy was better than bone marrow aspiration. However, because bilateral biopsy is the gold standard, we recommend using this and bone marrow aspiration simultaneously to evaluate a pediatric patient with any malignancy potentially infiltrating bone marrow.

Treatment of non-Hodgkin's lymphoma in Mexican children: the effectiveness of chemotherapy during malnutrition

The histological diagnosis of non-Hodgkins lymphoma (Burkitts lymphoma excluded) in 147 children was reviewed. The most common site of presentation was in the abdomen (32.6%). The most frequent site of metastatic disease at diagnosis was the bone marrow (27.2%). The most common histology was diffuse undifferentiated non-Burkitt type (37.4%). According to the Murphy staging system, 40.1% were stage III and 27.2% were stage IV. In a nonrandomized prospective study, 121 patients were submitted to a treatment regimen (protocol 8001) and compared with 26 historical controls treated with the COP regimen, consisting of cyclophosphamide, vincristine and prednisone. Of those patients treated with protocol 8001, nine had intestinal perforation at the site of primary disease. All patients in this group were malnourished at the time of perforation. The overall rate of initial complete remission in those patients treated with protocol 8001 was 90.7%. The duration of remission was from 16 to 108 months, with a median of 39 months. The actuarial rate of disease-free survival was 69% at 2 years and 63% at 6 years, compared with 36% at 6 years of the control group (COP) (p < 0.01). None of the patients have relapsed after 4 years.