International journal of radiation oncology, biology, physics
-
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.
-
Int. J. Radiat. Oncol. Biol. Phys. · May 2004
Erythropoietin-induced reduction of hypoxia before and during fractionated irradiation contributes to improvement of radioresponse in human glioma xenografts.
Our study investigated the influence of recombinant human erythropoietin (rHuEPO) treatment, inducing raised hemoglobin levels in nonanemic mice, on intratumor oxygenation before and during fractionated irradiation. Furthermore, the consequences of rHuEPO administration on tumor response to fractionated radiotherapy (RT) were evaluated. ⋯ Our results indicate that rHuEPO, by enhancing blood oxygen-carrying capacity, decreases intrinsic tumor hypoxia and maintains its effect during fractionated irradiation in malignant glioma xenografts. Therefore, rHuEPO contributes to radiosensitize these tumors.
-
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.
-
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.