ABSTRACT
Leukemia incidence in children has increased worldwide in recent decades, particularly due to the rise in acute lymphoblastic leukemia. Studies have associated exposure to non-ionizing radiation generated by low frequency magnetic fields with childhood leukemia. The current article reviews the case-control studies published on this subject. Of 152 articles tracked in different databases, ten studies from North America, Asia, and Europe met the defined selection criteria, with patients diagnosed from 1960 to 2004. Methodological limitations were observed in these articles, including difficulties with the procedures for assessing exposure. An association may exist between exposure to low frequency magnetic fields and acute lymphoblastic leukemia in children, but this association is weak, preventing the observation of consistency in the findings. Future studies from a wider range of geographic regions should focus on the analysis of acute lymphoblastic leukemia, which is the subtype with the greatest impact on the increasing overall incidence of childhood leukemia.
Subject(s)
Electromagnetic Fields/adverse effects , Environmental Exposure/adverse effects , Leukemia, Radiation-Induced/etiology , Precursor Cell Lymphoblastic Leukemia-Lymphoma/etiology , Case-Control Studies , Child , Humans , Incidence , Leukemia, Radiation-Induced/epidemiology , Odds Ratio , Precursor Cell Lymphoblastic Leukemia-Lymphoma/epidemiology , Radiation Dosage , Risk FactorsABSTRACT
Leukemia incidence in children has increased worldwide in recent decades, particularly due to the rise in acute lymphoblastic leukemia. Studies have associated exposure to non-ionizing radiation generated by low frequency magnetic fields with childhood leukemia. The current article reviews the case-control studies published on this subject. Of 152 articles tracked in different databases, ten studies from North America, Asia, and Europe met the defined selection criteria, with patients diagnosed from 1960 to 2004. Methodological limitations were observed in these articles, including difficulties with the procedures for assessing exposure. An association may exist between exposure to low frequency magnetic fields and acute lymphoblastic leukemia in children, but this association is weak, preventing the observation of consistency in the findings. Future studies from a wider range of geographic regions should focus on the analysis of acute lymphoblastic leukemia, which is the subtype with the greatest impact on the increasing overall incidence of childhood leukemia.
A incidência de leucemias em crianças tem aumentado nas últimas décadas no mundo, com influência predominante da leucemia linfocítica aguda, principal subtipo em crianças. Estudos têm relacionado a exposição às radiações não-ionizantes geradas pelos campos magnéticos de baixa freqüência com leucemia infantil. Neste artigo foram revisados os estudos caso-controle publicados sobre essa questão. Dos 152 artigos localizados em diferentes bases de dados, dez estudos da América do Norte, Ásia e Europa preencheram os critérios de seleção, comportando pacientes diagnosticados entre 1960 e 2004. Algumas limitações metodológicas foram observadas como dificuldades nos procedimentos de avaliação da exposição. É possível a existência de associação entre exposição a campos magnéticos de baixa freqüência e leucemia linfocítica aguda em crianças, porém, a força desta associação é tênue, impedindo observar consistência entre os resultados. Futuros estudos, com maior diversidade de regiões, deveriam concentrar-se na análise da leucemia linfocítica aguda, pois é o subtipo com maior influência na incidência crescente da leucemia infantil.
Subject(s)
Humans , Child , Electromagnetic Fields/adverse effects , Environmental Exposure/adverse effects , Leukemia, Radiation-Induced/etiology , Precursor Cell Lymphoblastic Leukemia-Lymphoma/etiology , Case-Control Studies , Incidence , Leukemia, Radiation-Induced/epidemiology , Odds Ratio , Precursor Cell Lymphoblastic Leukemia-Lymphoma/epidemiology , Radiation Dosage , Risk FactorsABSTRACT
We performed a randomized clinical trial to assess the usefulness and toxicity of combined therapy compared with chemotherapy and radiotherapy in the treatment of early stage Hodgkin's disease with bulky disease as an adverse prognostic factor. Three-hundred and seven patients were enrolled into the study. They were randomized to receive either radiotherapy (extended field, generally mantle, 3500 cGy), or chemotherapy (adriamycin, bleomicin, vinblastine and dacarbazine: ABVD, 6 monthly) cycles or combined therapy (three cycles of ABVD, followed by irradiation therapy and three more cycles of chemotherapy). The median follow-up duration from start of treatment was 11.4 years. Complete response rates were similar in the three arms: 83% for radiotherapy (95% confidence interval [CI] 67-92%), 80% for chemotherapy (CI 69-88%) and 87% for combined therapy (CI 74-94%). However, disease-free survival and overall survival were better in the patients treated with combined therapy. At 12 years 76% (CI 51-93%) of the patients treated with combined therapy remained alive in the first complete remission compared with 42% (CI 26-61%) in patients treated with radiotherapy and 48% (CI 31-57%) in patients who had received chemotherapy alone (P < 0.01). Improvement in overall survival was also evident at 12 years: 88% (CI 59-93%) in those who had received combined therapy, compared with 53% (CI 36-67%) in the radiotherapy arm and 59% (CI 35-67%) in the chemotherapy group. Acute toxicity was more frequent in patients treated with combined therapy, but no death related treatment was observed in the three groups. Late toxicity was similar in the three treatment groups. Combined therapy with extended field radiotherapy and six cycles of chemotherapy is an effective treatment of patients with early stage bulky Hodgkin's disease compared with chemotherapy or radiotherapy alone.
Subject(s)
Hodgkin Disease/therapy , Radiotherapy, High-Energy , Antineoplastic Combined Chemotherapy Protocols/adverse effects , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Bleomycin/administration & dosage , Combined Modality Therapy/adverse effects , Dacarbazine/administration & dosage , Disease-Free Survival , Doxorubicin/administration & dosage , Follow-Up Studies , Gastrointestinal Diseases/etiology , Hematologic Diseases/etiology , Hodgkin Disease/drug therapy , Hodgkin Disease/mortality , Hodgkin Disease/radiotherapy , Humans , Leukemia, Radiation-Induced/etiology , Life Tables , Lymphoma/chemically induced , Neoplasms, Second Primary/chemically induced , Neoplasms, Second Primary/etiology , Nervous System Diseases/etiology , Prospective Studies , Pulmonary Fibrosis/etiology , Radiation Injuries/etiology , Radiotherapy, High-Energy/adverse effects , Remission Induction , Survival Analysis , Treatment Outcome , Vinblastine/administration & dosageABSTRACT
The incidence of secondary malignancy was assessed in 537 patients with Hodgkin's disease treated with radiotherapy (128 patients), chemotherapy alone (156 patients), or in combined modality therapy (253 patients) between January 1973 to September 1985 with a median follow-up of 7.5 years. The dose of radiation therapy, dose of cytotoxic drugs and sequence of treatment was carefully analyzed. No cases of acute leukemia or other secondary malignant disease were identified in these cases. No differences in clinical laboratory features or treatments were identified in relation to previous reports. Racial difference is the unique feature which seems to avoid the development of this complication in patients treated for Hodgkin's disease. We hope that other reports in Latin America can contribute to the identification of race as the difference.