International journal of radiation oncology, biology, physics
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 1997
Recursive partitioning analysis (RPA) of prognostic factors in three Radiation Therapy Oncology Group (RTOG) brain metastases trials.
Promising results from new approaches such as radiosurgery or stereotactic surgery of brain metastases have recently been reported. Are these results due to the therapy alone or can the results be attributed in part to patient selection? An analysis of tumor/patient characteristics and treatment variables in previous Radiation Therapy Oncology Group (RTOG) brain metastases studies was considered necessary to fully evaluate the benefit of these new interventions. ⋯ Based on this analysis, we suggest the following three classes: Class 1: patients with KPS > or = 70, < 65 years of age with controlled primary and no extracranial metastases; Class 3: KPS < 70; Class 2- all others. Using these classes or stages, new treatment techniques can be tested on homogeneous patient groups.
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 1997
Metastatic carcinoma in the cervical lymph nodes from an unknown primary site: results of bilateral neck plus mucosal irradiation vs. ipsilateral neck irradiation.
To compare the outcome for patients with squamous cell carcinoma of cervical lymph nodes metastatic from an unknown primary site who were irradiated to both sides of the neck and potential mucosal sites with opposed photon beams, and for those irradiated to the ipsilateral side of the neck alone with an electron beam. ⋯ Bilateral neck and mucosal irradiation is superior to ipsilateral neck irradiation in preventing contralateral cervical lymph node metastases and the subsequent appearance of an occult primary cancer. Both techniques combined with cervical lymph node dissection were equally effective in controlling the ipsilateral neck disease.
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 1997
Biological effect of pulsed dose rate brachytherapy with stepping sources if short half-times of repair are present in tissues.
To explore the possible increase of radiation effect in tissues irradiated by pulsed brachytherapy (PDR) for local tissue dose rates between those "averaged over the whole pulse" and the instantaneous high dose rates close to the dwell positions. Increased effect is more likely for tissues with short half-times of repair of the order of a few minutes, similar to pulse durations. ⋯ Therefore, about 75% of the total dose is delivered at HDR in a PDR implant of moderate volume, reducing to 40% as the source decays from 1 to 0.3 curies. Even so, restricting the dose per pulse to 0.5 or 0.6 Gy should avoid ratios of increased effect larger than about 10%. It appears likely that PDR delivered by stepping source might behave more like HDR than LDR, especially for tissues with a substantial component of repair of very short T1/2.