International journal of radiation oncology, biology, physics
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Int. J. Radiat. Oncol. Biol. Phys. · May 2004
Intensity-modulated radiation therapy for oropharyngeal carcinoma: impact of tumor volume.
To assess the therapeutic outcomes in oropharyngeal cancer patients treated with intensity-modulated radiotherapy (IMRT) and analyze the impact of primary gross tumor volume (GTV) and nodal GTV (nGTV) on survival and locoregional control rates. ⋯ IMRT is an effective treatment modality for locally advanced oropharyngeal carcinoma. The GTV and nGTV are the most important factors predictive of therapeutic outcome.
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Int. J. Radiat. Oncol. Biol. Phys. · May 2004
Dosimetry and radiobiologic model comparison of IMRT and 3D conformal radiotherapy in treatment of carcinoma of the prostate.
Intensity-modulated radiotherapy (IMRT) has introduced novel dosimetry that often features increased dose heterogeneity to target and normal structures. This raises questions of the biologic effects of IMRT compared to conventional treatment. We compared dosimetry and radiobiologic model predictions of tumor control probability (TCP) and normal tissue complication probability (NTCP) for prostate cancer patients planned for IMRT as opposed to standardized three-dimensional conformal radiotherapy (3DCRT). ⋯ Dose to the prostate, expressed as mean +/- standard deviation, was 74.7 +/- 1.1 Gy for IMRT vs. 74.6 +/- 0.3 Gy for 3D for the LFI plans, and 74.8 +/- 0.6 Gy for IMRT vs. 71.5 +/- 0.6 Gy for 3D for the EFI plans. For the studied protocols, TCP was greater for IMRT than for 3D across the full range of target sensitivity, for both localized- and extended-field irradiation. For LFI, this was due to the smaller number of fractions (35 vs. 37) used for IMRT, and for EFI, this was due to the greater mean dose for IMRT, compared to 3D. For all organs, mean NTCP tended to be lower for IMRT than for 3D, although NTCP values were very small for both 3D and IMRT. Differences were statistically significant for rectum (LFI and EFI), bladder (EFI), and bowel (EFI). For both LFI and EFI, the calculated NTCPs qualitatively agreed with early published clinical data comparing genitourinary and gastrointestinal complications of IMRT and 3D. Present calculations support the hypothesis that accurately delivered IMRT for prostate cancer can limit dose to normal tissue by reducing treatment margins relative to conventional 3D planning, to allow a reduction in complication rate spanning several sensitive structures while maintaining or increasing tumor control probability.
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Int. J. Radiat. Oncol. Biol. Phys. · May 2004
Comparative StudyClinical comparison of two linear-quadratic model-based isoeffect fractionation schemes of high-dose-rate intracavitary brachytherapy for cervical cancer.
Two linear-quadratic model-based isoeffect fractionation schemes of high-dose-rate intracavitary brachytherapy (HDR-IC) were used to treat cervical cancer in two consecutive periods. Patient outcomes and complications were analyzed and compared. ⋯ The treatment results of the two groups maintained similar outcomes, while the complications decreased. The linear-quadratic model correctly predicted this outcome. Biologically, the manipulation of the fraction size in our study suggested that the sensitivity of the late responding tissue to the fractional change from 7.2 Gy to 4.8 Gy in HDR-IC is high and detectable clinically. The success, however, had its limitations, and the improvement was confined to low-grade complications.
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Int. J. Radiat. Oncol. Biol. Phys. · May 2004
Comparative StudyImpact of FDG-PET on radiation therapy volume delineation in non-small-cell lung cancer.
Locoregional failure remains a significant problem for patients receiving definitive radiation therapy alone or combined with chemotherapy for non-small-cell lung cancer (NSCLC). Positron emission tomography (PET) with [(18)F]fluoro-2-deoxy-d-glucose (FDG) has proven to be a valuable diagnostic and staging tool for NSCLC. This prospective study was performed to determine the impact of treatment simulation with FDG-PET and CT on radiation therapy target volume definition and toxicity profiles by comparison to simulation with computed tomography (CT) scanning alone. ⋯ Radiation targeting with fused FDG-PET and CT images resulted in alterations in radiation therapy planning in over 50% of patients by comparison with CT targeting. The increasing availability of integrated PET/CT units will facilitate the use of this technology for radiation treatment planning. A confirmatory multicenter, cooperative group trial is planned within the Radiation Therapy Oncology Group.
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Int. J. Radiat. Oncol. Biol. Phys. · May 2004
Pilot study of postoperative reirradiation, chemotherapy, and amifostine after surgical salvage for recurrent head-and-neck cancer.
Salvage surgery alone after radiotherapy (RT) failure for locally advanced head-and-neck cancer is frequently unsuccessful because of subsequent recurrence. We designed a prospective protocol to determine the feasibility, toxicity, and preliminary efficacy of a regimen of postoperative reirradiation, chemotherapy and the radioprotector amifostine after salvage head-and-neck surgery. ⋯ This regimen of postoperative reirradiation/chemotherapy plus amifostine is feasible and was well tolerated acutely, with encouraging oncologic efficacy. However, the incidence and severity of late effects was significant and suggests that modifications are necessary for future studies in this patient population.