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dc.contributor.authorRoberts, Stephen A
dc.contributor.authorHendry, Jolyon H
dc.contributor.authorBrewster, Alison E
dc.contributor.authorSlevin, Nicholas J
dc.date.accessioned2010-01-25T09:53:41Z
dc.date.available2010-01-25T09:53:41Z
dc.date.issued1994-08
dc.identifier.citationThe influence of radiotherapy treatment time on the control of laryngeal cancer: a direct analysis of data from two British Institute of Radiology trials to calculate the lag period and the time factor. 1994, 67 (800):790-4 Br J Radiolen
dc.identifier.issn0007-1285
dc.identifier.pmid8087485
dc.identifier.urihttp://hdl.handle.net/10541/90515
dc.description.abstractThis study analyses node-negative laryngeal tumour control data from two clinical trials conducted by the British Institute of Radiology in order to determine the time factors and the presence or absence of a lag period before the time factor takes effect. A direct maximum likelihood approach is used to fit a double-logarithmic model including a repopulation term which commences after an initial lag period, Tk. The analysis yields a time factor of 0.8 Gy per day (95% confidence interval 0.5-1.1 Gy per day) as the extra dose required to counteract the reduction in tumour control probability (TCP) with extension of the treatment time. The latter reduction amounted to between 5 and 12% TCP per week, depending on the stage and time period. With this dataset, where few patients were treated for short times, no statistically significant lag phase can be demonstrated. However, the best estimate of Tk is 21 days (95% confidence interval 0-27 days), which is consistent with estimates from other studies on other datasets. If a lag phase exists, this study would indicate that the duration is less than 27 days. Other studies have used retrospective data and are subject to a number of potential biases. The present study, using data from multicentre prospective randomized clinical trials, is free from some of these sources of bias. The fact that very similar estimates of the radiobiological parameters are obtained lends credence to these other studies and suggests that the potential biases may be small in practice.
dc.language.isoenen
dc.subjectCancer Recurrenceen
dc.subjectLaryngeal Canceren
dc.subject.meshClinical Trials as Topic
dc.subject.meshHumans
dc.subject.meshLaryngeal Neoplasms
dc.subject.meshModels, Statistical
dc.subject.meshNeoplasm Recurrence, Local
dc.subject.meshRadiology
dc.subject.meshRadiotherapy Dosage
dc.subject.meshSocieties, Medical
dc.subject.meshTime Factors
dc.subject.meshTreatment Outcome
dc.titleThe influence of radiotherapy treatment time on the control of laryngeal cancer: a direct analysis of data from two British Institute of Radiology trials to calculate the lag period and the time factor.en
dc.typeArticleen
dc.contributor.departmentBiomathematics and Computing Unit, Paterson Institute for Cancer Research, Manchester, UK.en
dc.identifier.journalThe British Journal of Radiologyen
html.description.abstractThis study analyses node-negative laryngeal tumour control data from two clinical trials conducted by the British Institute of Radiology in order to determine the time factors and the presence or absence of a lag period before the time factor takes effect. A direct maximum likelihood approach is used to fit a double-logarithmic model including a repopulation term which commences after an initial lag period, Tk. The analysis yields a time factor of 0.8 Gy per day (95% confidence interval 0.5-1.1 Gy per day) as the extra dose required to counteract the reduction in tumour control probability (TCP) with extension of the treatment time. The latter reduction amounted to between 5 and 12% TCP per week, depending on the stage and time period. With this dataset, where few patients were treated for short times, no statistically significant lag phase can be demonstrated. However, the best estimate of Tk is 21 days (95% confidence interval 0-27 days), which is consistent with estimates from other studies on other datasets. If a lag phase exists, this study would indicate that the duration is less than 27 days. Other studies have used retrospective data and are subject to a number of potential biases. The present study, using data from multicentre prospective randomized clinical trials, is free from some of these sources of bias. The fact that very similar estimates of the radiobiological parameters are obtained lends credence to these other studies and suggests that the potential biases may be small in practice.


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