International journal of radiation oncology, biology, physics
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Int. J. Radiat. Oncol. Biol. Phys. · Jun 2002
Relative biological effectiveness (RBE) values for proton beam therapy.
Clinical proton beam therapy has been based on the use of a generic relative biological effectiveness (RBE) of 1.0 or 1.1, since the available evidence has been interpreted as indicating that the magnitude of RBE variation with treatment parameters is small relative to our abilities to determine RBEs. As substantial clinical experience and additional experimental determinations of RBE have accumulated and the number of proton radiation therapy centers is projected to increase, it is appropriate to reassess the rationale for the continued use of a generic RBE and for that RBE to be 1.0-1.1. ⋯ At present, there is too much uncertainty in the RBE value for any human tissue to propose RBE values specific for tissue, dose/fraction, proton energy, etc. The experimental in vivo and clinical data indicate that continued employment of a generic RBE value and for that value to be 1.1 is reasonable. However, there is a local "hot region" over the terminal few millimeters of the SOBP and an extension of the biologically effective range. This needs to be considered in treatment planning, particularly for single field plans or for an end of range in or close to a critical structure. There is a clear need for prospective assessments of normal tissue reactions in proton irradiated patients and determinations of RBE values for several late responding tissues in laboratory animal systems, especially as a function of dose/fraction in the range of 1-4 Gy.
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To study and report 6 patients with radiation recall in unique sites, secondary to gemcitabine chemotherapy. ⋯ Radiation recall from gemcitabine chemotherapy is rare, but can potentially arise in any site that has been previously irradiated. Treating physicians must be aware of this potential toxicity from gemcitabine and radiation and discontinue the gemcitabine if radiation recall is observed.
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Int. J. Radiat. Oncol. Biol. Phys. · Jun 2002
Comparative StudyPrognostic significance of race on biochemical control in patients with localized prostate cancer treated with permanent brachytherapy: multivariate and matched-pair analyses.
To compare PSA relapse-free survival (PSA-RFS) between African-American (AA) and white American (WA) males treated with permanent prostate brachytherapy (PPB) for clinically localized prostate cancer. ⋯ Race is not an independent predictor of 5-year PSA-RFS in patients with localized prostate cancer treated with PPB. This result is consistent with other studies that also show that race does not contribute to differences in outcome after definitive therapies for localized prostate cancer.
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Int. J. Radiat. Oncol. Biol. Phys. · Jun 2002
Concomitant chemoirradiation for stage III-IV nasopharyngeal carcinoma in Chinese patients: results of a matched cohort analysis.
To evaluate the toxicity and efficacy of concomitant chemoirradiation (CRT) followed by adjuvant chemotherapy compared with radiotherapy (RT) alone in Chinese patients with locoregionally advanced nasopharyngeal carcinoma (NPC). ⋯ Our experience indicates that concomitant CRT improves locoregional control in Chinese patients with locoregionally advanced NPC, but our analyses failed to detect any impact on distant failure and survival. The failure to reduce distant metastasis and improve survival may have related in part to the more advanced disease stage in our patients and the relatively low compliance rate of adjuvant chemotherapy. Our findings suggest caution should be exercised in extrapolating the findings of the Intergroup Study 0099 to Chinese patients, and confirmatory results from prospective randomized studies in the endemic population are needed.
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Int. J. Radiat. Oncol. Biol. Phys. · Jun 2002
Dose escalation using conformal high-dose-rate brachytherapy improves outcome in unfavorable prostate cancer.
To overcome radioresistance for patients with unfavorable prostate cancer, a prospective trial of pelvic external beam irradiation (EBRT) interdigitated with dose-escalating conformal high-dose-rate (HDR) prostate brachytherapy was performed. ⋯ Pelvic EBRT interdigitated with transrectal ultrasound-guided real-time conformal HDR prostate brachytherapy boost is both a precise dose delivery system and a very effective treatment for unfavorable prostate cancer. We demonstrated an incremental beneficial effect on biochemical control and cause-specific survival with higher doses. These results, coupled with the low risk of complications, the advantage of not being radioactive after implantation, and the real-time interactive planning, define a new standard for treatment.