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1.
Int J Radiat Oncol Biol Phys ; 93(3): 658-67, 2015 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-26461008

RESUMO

PURPOSE: To investigate the roles of radiation therapy and chemotherapy in the occurrence of subsequent leukemia after childhood cancer. METHODS AND MATERIALS: We analyzed data from a case-control study with 35 cases and 140 controls. The active bone marrow (ABM) was segmented into 19 compartments, and the radiation dose was estimated in each. The chemotherapy drug doses were also estimated to enable adjustments. Models capable of accounting for radiation dose heterogeneity were implemented for analysis. RESULTS: Univariate analysis showed a significant trend in the increase of secondary leukemia risk with radiation dose, after accounting for dose heterogeneity (P=.046). This trend became nonsignificant after adjustment for doses of epipodophyllotoxins, alkylating agents, and platinum compounds and the first cancer on multivariate analysis (P=.388). The role of the radiation dose appeared to be dwarfed, mostly by the alkylating agents (odds ratio 6.9, 95% confidence interval 1.9-25.0). Among the patients who have received >16 Gy to the ABM, the radiogenic risk of secondary leukemia was about 4 times greater in the subgroup with no alkylating agents than in the subgroup receiving ≥10 g/m(2). CONCLUSIONS: Notwithstanding the limitations resulting from the size of our study population and the quite systematic co-treatment with chemotherapy, the use of detailed information on the radiation dose distribution to ABM enabled consideration of the role of radiation therapy in secondary leukemia induction after childhood cancer.


Assuntos
Antineoplásicos/efeitos adversos , Medula Óssea/efeitos dos fármacos , Medula Óssea/efeitos da radiação , Leucemia Induzida por Radiação , Leucemia/induzido quimicamente , Neoplasias/terapia , Adolescente , Análise de Variância , Antineoplásicos Alquilantes/efeitos adversos , Estudos de Casos e Controles , Criança , Pré-Escolar , Intervalos de Confiança , Feminino , Humanos , Lactente , Masculino , Segunda Neoplasia Primária/etiologia , Razão de Chances , Compostos de Platina/efeitos adversos , Podofilotoxina/efeitos adversos , Doses de Radiação
2.
J Clin Endocrinol Metab ; 100(11): 4282-90, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26327481

RESUMO

CONTEXT: Thyroid carcinoma is a frequent complication of childhood cancer radiotherapy. The dose response to thyroid radiation dose is now well established, but the potential modifier effect of other factors requires additional investigation. OBJECTIVE: This study aimed to investigate the role of potential modifiers of the dose response. DESIGN: We followed a cohort of 4338 5-year survivors of solid childhood cancer treated before 1986 over an average of 27 years. The dose received by the thyroid gland and some other anatomical sites during radiotherapy was estimated after reconstruction of the actual conditions in which irradiation was delivered. RESULTS: Fifty-five patients developed thyroid carcinoma. The risk of thyroid carcinoma increased with a radiation dose to the thyroid of up to two tenths of Gy, then leveled off for higher doses. When taking into account the thyroid radiation dose, a surgical or radiological splenectomy (>20 Gy to the spleen) increased thyroid cancer risk (relative risk [RR] = 2.3; 95% confidence interval [CI], 1.3-4.0), high radiation doses (>5 Gy) to pituitary gland lowered this risk (RR = 0.2; 95% CI, 0.1-0.6). Patients who received nitrosourea chemotherapy had a 6.6-fold (95% CI, 2.5-15.7) higher risk than those who did not. The excess RR per Gy of radiation to the thyroid was 4.7 (95% CI, 1.7-22.6). It was 7.6 (95% CI, 1.6-33.3) if body mass index at time of interview was equal or higher than 25 kg/m(2), and 4.1 (95% CI, 0.9-17.7) if not (P for interaction = .1). CONCLUSION: Predicting thyroid cancer risk following childhood cancer radiation therapy probably requires the assessment of more than just the radiation dose to the thyroid. Chemotherapy, splenectomy, radiation dose to pituitary gland, and obesity also play a role.


Assuntos
Neoplasias Induzidas por Radiação/epidemiologia , Radioterapia/efeitos adversos , Neoplasias da Glândula Tireoide/epidemiologia , Adolescente , Antineoplásicos/efeitos adversos , Criança , Pré-Escolar , Estudos de Coortes , Relação Dose-Resposta à Radiação , Humanos , Incidência , Lactente , Recém-Nascido , Compostos de Nitrosoureia/efeitos adversos , Obesidade/complicações , Obesidade/epidemiologia , Hipófise/efeitos da radiação , Doses de Radiação , Estudos Retrospectivos , Fatores de Risco , Esplenectomia , Glândula Tireoide/efeitos da radiação
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