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Purpose-To review institutional outcomes for patients treated for differentiated thyroid cancer with post-operative conformal external beam radiotherapy (EBRT).Methods-This is a single institution retrospective review of one hundred thirty-one consecutive patients with differentiated thyroid cancer who underwent EBRT between 1/1996 and 12/2005. Histologic diagnoses included 104 papillary, 21 follicular, and 6 mixed papillary-follicular. AJCC stage distribution was 2 stage III, 128 stage IVa-c, and not accessible in 1. Thirty-four (26%) patients had high-risk histology and 76 (58%) had recurrent disease. Extraglandular disease spread was seen in 126 (96%) cases, microscopically positive surgical margins in 62 (47%) and gross residual disease in 15 (11%). Median EBRT dose was 60 Gy [range: 38-72 Gy]. Fifty-seven (44%) patients were treated with IMRT to a median dose of 60 . Median follow-up was 38 months (range: 0-134).Results-Kaplan-Meier estimates of locoregional relapse free survival (LRFS), disease specific survival (DSS), and overall survival (OS) at 4 years were 79%, 76%, and 73%, respectively. On multivariate analysis, high-risk histologic features and gross residual disease predicted for inferior LRFS, while high-risk histologic features, M1 disease, and gross residual disease predicted for inferior DSS and OS. IMRT did not impact survival outcomes, but was associated with less frequent severe late morbidity (12% vs.2%).

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Purpose-To quantify the differences between planned and delivered parotid gland and target doses, and to assess the benefits of daily bone alignment for head-and-neck cancer patients treated with intensity-modulated radiotherapy (IMRT).Methods and Materials-Eleven head-and-neck cancer patients received 2 CT scans/week with an in-room CT scanner over their course of radiotherapy. The clinical IMRT plans, designed with 3-4mm planning margins, were recalculated on the repeat CT images. The plans were aligned using (1) the actual treatment isocenter marked with radiopaque markers (BB) and (2) bone alignment to the cervical vertebrae to simulate image-guided setup. In-house deformable image registration software was used to map daily dose distributions to the original treatment plan and to calculate a cumulative, delivered dose distribution for each patient.Results-Using conventional BB alignment led to increases in the parotid gland mean dose above the planned dose by 5-7Gy in 45% of the patients (median = 3.0Gy ipsilateral (p=0.026); median = 1.0Gy contralateral (p=0.016)). Use of bone alignment led to reductions relative to BB alignment in 91% of patients (median=2Gy; range=0.3-8.3Gy; 15 of 22 parotids improved). However, the parotid dose from bone alignment was still greater than planned (median=1.0Gy (p=0.007)). Neither approach affected tumor dose coverage.Conclusions-With conventional BB alignment, the parotid gland mean dose was significantly increased above the planned mean dose. Using daily bone alignment reduced the parotid dose compared to BB alignment in almost all patients. A 3-4 mm planning margin was adequate for tumor dose coverage.Correspondence and reprint requests to: