A randomised controlled trial of forward-planned radiotherapy (IMRT) for early breast cancer: Baseline characteristics and dosimetry results

Department of Oncology, University of Cambridge, Cambridge, UK.
Radiotherapy and Oncology (Impact Factor: 4.36). 04/2009; 92(1):34-41. DOI: 10.1016/j.radonc.2009.03.003
Source: PubMed


This large trial was designed to investigate whether correction of dose inhomogeneities using intensity-modulated radiotherapy (IMRT) reduces late toxicity and improves quality of life in patients with early breast cancer. This paper reports baseline characteristics of trial participants and dosimetry results.
Standard tangential plans of 1145 trials were analysed. Patients with inhomogeneous plans, defined by ICRU recommendations, were randomised to forward-planned IMRT or standard radiotherapy.
Twenty-nine percentage of patients had adequate dosimetry with standard 2D radiotherapy. In the randomised patients, the decreases in mean volumes receiving greater than 107% (Vol>107) and less than 95% (Vol<95) of the prescribed dose in the IMRT compared with the control group were 34.0 cm(3) (95% CI 26.4-41.6; P<0.0001) and 48.1 cm(3) (95% CI 34.4-61.9; P<0.0001), respectively. In this study, 90% of patients who had a breast separation greater > or = 21 cm had Vol>107>2 cm(3) on standard radiotherapy plans.
This large trial, in which patients with all breast sizes were eligible, confirmed that breast dosimetry can be significantly improved with a simple method of forward-planned IMRT and has little impact on radiotherapy resources. It is shown that patients with larger breasts are more likely to have dose inhomogeneities and breast separation gives some indication of this likelihood. Photographic assessment of patients at 2 years after radiotherapy, as the next part of this randomised controlled trial, will show whether these results for IMRT translate into improved cosmetic outcome in patients with early breast cancer. This would provide impetus for the widespread adoption of 3D planning and IMRT.

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    • "Veldeman conducted a systematic review of the clinical evidence for IMRT in 2008 which included 56 comparative studies, 3 of which were randomized controlled trials (RCTs) [11], and concluded that IMRT reduced treatment-related toxic effects and improved quality of life. A second systematic review in 2010 [12] reported reduced acute and late toxicity associated with IMRT [4-10,12,13]. Three RCTs reported significant improvement of acute xerostomia with the use of IMRT in head and neck cancers and better quality of life [6,7,9,13], and IMRT for breast cancer was also associated with reduced acute and late side effects when compared to 2D RT in three RCTs [4,5,8]. With further RCTs in progress [12], additional evidence will soon be available. "
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    • "In the patients with any volumes receiving >107%, the median percentage volume of treated breast receiving dose >107% was extremely small (0.1%). This figure for partial breast volumes receiving >107% of prescribed dose is consistent with previous reports in the literature [28]. The distribution of volume receiving >100% dose was split into quartiles for the analysis assessing the effect of dosimetry on risk of late adverse effects. "
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    • "An energy of 6 MV was used in most patients, but mixed energies of 6 and 15 MV photons were used when required in patients with larger separations. Nodal radiotherapy and a tumour bed boost were administered according to local protocols [2]. A boost was given to all patients except those deemed at low risk with all of the following: age >50 years, T1 stage, Grade 1 or 2, absence of lymph node metastases (including micrometastases), no lymphovascular space invasion, margins ≥5 mm (or 2 mm if anterior or deep margin and no more tissue to take). "
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