International journal of radiation oncology, biology, physics
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2000
Dose selection for prostate cancer patients based on dose comparison and dose response studies.
To better define the appropriate dose for individual prostate cancer patients treated with three-dimensional conformal radiation therapy (3D CRT). ⋯ Dose response varies by patient subgroup, and appropriate dose can be estimated for up to six subdivisions of prostate cancer patients. The appropriate use of high dose with 3D CRT results in 5-year cure rates that equal or exceed other treatments. The national practice must be upgraded to allow the safe administration of 75-80 Gy with 3D CRT.
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2000
Acute and late toxicity of patients with inflammatory bowel disease undergoing irradiation for abdominal and pelvic neoplasms.
Little data exists in the medical literature describing the response of patients with inflammatory bowel disease (IBD) to abdominal and pelvic irradiation. To clarify the use of this modality in this setting, this study assesses the short- and long-term tolerance of 28 patients with IBD to abdominal and pelvic irradiation. ⋯ Because of the potentially severe toxicity experienced by patients with IBD undergoing abdominal and pelvic irradiation, judicious use of this modality must be employed. Definition of IBD location and activity as well as careful attention to irradiation technique may allow treatment of these patients with acceptable rates of morbidity.
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2000
Preoperative chemoradiation in fixed distal rectal cancer: dose time factors for pathological complete response.
Preoperative chemoradiation is being utilized extensively in the treatment of rectal cancer. However, a variety of dose time factors in both delivery of chemotherapy and irradiation remain to be established. This study was undertaken to examine the impact of dose time factors on pathological complete response (pCR) rates following preoperative chemoradiation for fixed rectal cancer. ⋯ Dose intensity of 5-FU and dose of radiation correlate significantly with the likelihood of achieving a pCR. Continuous infusion 5-FU (CI) and a preoperative radiation dose of 5500 cGy or higher can achieve pCR rates of approximately 50%, even in fixed cancers of the rectum.
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Int. J. Radiat. Oncol. Biol. Phys. · Feb 2000
Comparative StudyScrutiny of the ASTRO consensus definition of biochemical failure in irradiated prostate cancer patients demonstrates its usefulness and robustness. American Society for Therapeutic Radiology and Oncology.
The goals of this study are: (1) to establish the robustness of the Fox Chase Cancer Center (FCCC) and the American Society for Therapeutic Radiology and Oncology (ASTRO) consensus definitions of failure by comparing biochemical estimates under various modifications of the censoring and failure time components to their respective unaltered definitions; (2) to isolate the source of variation between the two definitions of failure; and (3) to describe the hazard of failure over time for each definition. ⋯ Both FCCC and ASTRO failure definitions were robust to modifications in censoring and the inclusion of patients with long doubling times. The ASTRO failure definition was robust to specifying the time to failure at first rise, as opposed to midway between nadir and first rise. Similarities in estimates for all patients versus patients with agreeing failure status suggest that differences in failure definition lie in the specification of time to failure. The ASTRO definition of failure is more appropriate because it does not impose an empirical failure marker but is based on the initiation of biochemical rise. The use of the ASTRO consensus definition demonstrated little risk of biochemical failure 4 years beyond treatment. The ASTRO failure definition should be adopted in all research involving biochemical failure analysis of men treated with radiation therapy.
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Int. J. Radiat. Oncol. Biol. Phys. · Feb 2000
Radiobiological considerations in the design of fractionation strategies for intensity-modulated radiation therapy of head and neck cancers.
The dose distributions of intensity-modulated radiotherapy (IMRT) treatment plans can be shown to be significantly superior in terms of higher conformality if designed to simultaneously deliver high dose to the primary disease and lower dose to the subclinical disease or electively treated regions. We use the term "simultaneous integrated boost" (SIB) to define such a treatment. The purpose of this paper is to develop suitable fractionation strategies based on radiobiological principles for clinical trials and routine use of IMRT of head and neck (HN) cancers. The fractionation strategies are intended to allow escalation of tumor dose while adequately sparing normal tissues outside the target volume and considering the tolerances of normal tissues embedded within the primary target volume. ⋯ IMRT dose distributions are most conformal when designed to be delivered as SIB. Using isoeffect radiobiological relationships and published HN data, fractionation strategies can be designed in which the nominal dose levels to the primary, regional disease and electively treated volumes are appropriately adjusted, each receiving different dose/fx. Normal tissues outside the treated volumes are at reduced risk in such strategies since they receive lower total dose as well as lower dose/fx. However, the late effect toxicities of tissues embedded within the primary target volume and assumed to receive the same dose as the primary may pose a problem. The efficacy and safety of the proposed fractionation strategies will need to be evaluated with careful clinical trials.