Practical Prediction Model for Ovarian Insufficiency after Radiation / Modelo prático de predição para insuficiência ovariana após radiação

Abstract Objective The present study aimed to develop a useful mathematical model that predicts the age at which premature ovarian insufficiency might occur after teletherapy radiation. A diagnosis of premature or early menopause has physical and psychological consequences, so women may need support and long-term medical follow-up. Methods To correlate ovarian radiation dose with ovarian function, we used the formula described by Wallace et al.: √g(z) = 10(2-0,15z), where "g(z)" and "z" represent oocyte survival rate and the radiation dose (in Gray), respectively. By simulating different ages and doses, we observed a pattern that could be used to simplify the relationship between radiation dose and remaining time of ovarian function. Results We obtained a linear function between ovarian radiation dose and loss of ovarian function (LOF) that is the percentage of decrease in the time to the ovarian failure compared with the time expected for a woman at the same age without irradiation exposition. For patients <40 years old and with ovarian radiation doses < 5 Gy, the equation LOF = 2.70 + (11.08 × Dose) can be applied to estimate the decrease in time to premature ovarian insufficiency. Conclusion The present study reports a practicable theoretical method to estimate the loss of ovarian function. These findings can potentially improve the management and counseling of young women patients submitted to radiotherapy during their reproductive years.

Resumo Objetivo O presente estudo teve como objetivo desenvolver um modelo matemático útil que prediz a idade na qual a insuficiência ovariana prematura pode ocorrer após a radioterapia externa (teleterapia). O diagnóstico de menopausa prematura ou precoce tem consequências físicas e psicológicas; portanto, as mulheres podem precisar de apoio e acompanhamento médico de longo prazo. Métodos Para correlacionar a dose de radiação ovariana com a função ovariana, foi usada a fórmula descrita por Wallace et al.: √g(z) = 10(2-0,15z), na qual "g(z)" e "z" representam a taxa de sobrevivência do oócito e a dose de radiação (em Gray), respectivamente. Ao simular diferentes idades e doses, observamos um padrão que poderia ser usado para simplificar a relação entre a dose de radiação e o tempo restante da função ovariana. Resultados Obtivemos uma função linear entre a dose de radiação ovariana e a perda da função ovariana (LOF, na sigla em inglês) que é a porcentagem de diminuição no tempo até a falência ovariana em relação ao tempo esperado para uma mulher da mesma idade sem exposição à radiação. Para pacientes<40 anos de idade e com doses de radiação ovariana < 5 Gy, a equação LOF = 2,70 + (11,08 × Dose) pode ser aplicada para estimar a redução no tempo até a insuficiência ovariana. Conclusão O presente estudo relata um método teórico viável para estimar a perda da função ovariana. Estes achados podem melhorar potencialmente o manejo e o aconselhamento de pacientes jovens submetidas à radioterapia durante seus anos reprodutivos.

Definition of gross tumor volume with FDG-18F PET-CT in patients with head and neck cancer: comparison of different delineation methods

Objective: Besides the high sensitivity and specificity of positron emission tomography (PET) for head and neck tumors, there is still a lack of consensus about how to use this method inradiotherapy planning. The aim of this study is to compare different gross tumor volume (GTV) obtained with PET images in comparison to the size of the target volume generated with CT scanalone, for treated and untreated head and neck lesions. Methods: Sixty lesions in fifty patients with head and neck squamous cell carcinoma were included in the study. Delineation of the GTV was achieved using computed tomography (CT) images alone (GTV-CT) and PET-CT images with the visual assessment method (GTVPET-CT) and standard uptake value (SUV) thresholds of 40, 50, 60 and 75 percent (GTV40%, GTV50%, GTV60%, GTV75%, respectively). Correlations were measured by the Spearman test and the Friedman test was used to verify differences between GTVs. Results: For all lesions (treated and untreated), only the GTVPET-CT showed a strong correlation with GTV-CT. For only the untreated lesions, GTVPET-CT and GTV75% showed a strong correlation with GTV-CT. The GTV50%, GTV60% and GTV75% showed statistically significant difference in relation to GTV-CT, while GTVPET-CT and GTV40% were similar to GTV-CT. Conclusion: The use of PET-CT changes the volume of the final target in head and neck tumors,depending on the methodology used to calculate the GTV. The results presented here showed that the GTV40% and the GTVPET-CT are those who are closer to the target volumes delineated by conventional CT

Impacto da nutrição enteral na toxicidade aguda e na continuidade do tratamento dos pacientes com tumores de cabeça e pescoço submetidos a radioterapia com intensidade modulada / Impact of enteral nutrition on acute toxicity and treatment continuity in head and neck cancer patients submitted to intensity-modulated radiotherapy

OBJETIVO: Analisar o impacto da terapia nutricional enteral na manutenção do peso corpóreo e na necessidade de replanejamento e/ou interrupção da radioterapia em pacientes com câncer de cabeça e pescoço submetidos a radioterapia de intensidade modulada (IMRT). MATERIAIS E MÉTODOS: Foram analisados, retrospectivamente, os pacientes submetidos a IMRT entre janeiro de 2005 e outubro de 2008, com a inclusão de 83 casos. RESULTADOS: A idade mediana foi de 58,6 anos. Em apenas em cinco pacientes (6 por cento) houve interrupção do tratamento, que variou de 4 a 18 dias, e em 19 casos (23 por cento) houve necessidade de replanejamento. A terapia nutricional enteral foi instituída antes do início da radioterapia em 16 pacientes (19 por cento). Perda de peso > 5 por cento ocorreu em 58 casos (70 por cento), sendo mais prevalente no grupo de pacientes em que a terapia nutricional enteral não foi instituída pré-radioterapia. Na comparação entre os grupos não houve diferença significativa na realização de replanejamento (25 por cento versus 21 por cento; p = 0,741) ou na ocorrência e duração da interrupção da radioterapia. CONCLUSÃO: A terapia nutricional enteral tem um claro ganho na manutenção do peso corporal, porém, não houve um benefício na realização da gastrostomia percutânea endoscópica ou da sonda nasoenteral em relação à interrupção e ao replanejamento da radioterapia.

OBJECTIVE: The present study was aimed at analyzing the impact of enteral nutrition on the maintenance of body weight and on the necessity of replanning and/or interruption of treatment of head and neck cancer patients undergoing intensity-modulated radiotherapy (IMRT). MATERIALS AND METHODS: Cases of patients submitted to IMRT in the period from January 2005 to October 2008 were retrospectively reviewed, and 83 of them were included in the study. RESULTS: Median patients' age was 58.6 years. Only five patients (6 percent) had their treatment interrupted for a period ranging from 4 to 18 days, and in 19 cases (23 percent) required replanning. Enteral nutrition was initiated before the radiotherapy in 16 patients (19 percent). Weight loss of > 5 percent was observed in 58 patients (70 percent), with a higher prevalence in the group of patients who had not received pre-radiotherapy enteral nutrition. No significant difference was observed between the groups regarding the necessity of radiotherapy replanning (25 percent versus 21 percent; p = 0.741) and necessity and duration of treatment interruption. CONCLUSION: Enteral nutrition is of a great value in the body weight maintenance, but no benefit was observed with the performance of endoscopic percutaneous gastrostomy as compared with radiotherapy interruption/replanning.