Radiation oncology investigations
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Radiat Oncol Investig · Jan 1999
Comparative StudyLong-term complications with prostate implants: iodine-125 vs. palladium-103.
The linear quadratic model predicts that the normal tissue biologically effective dose (BED) will be lower with palladium-103 (Pd-103) vs. iodine-125 (I-125) for the currently prescribed minimum tumor doses (MTD) used for I-125 (160 Gy) and Pd-103 (115 Gy) prostate cancer brachytherapy. The predicted BEDs for I-125 and Pd-103 suggest that the long-term complication rates should be lower with Pd-103 vs. I-125 in clinical practice. ⋯ Pd-103. Assuming that the MTD for Pd-103 may be increased to produce an equivalent late-reacting normal tissue BED to that for I-125, then the radiobiology model predicts the log10 cell kill for Pd-103 implant will be greater than that of an I-125 implant for all tumor doubling times (high-grade tumors and low-grade tumors). The implications of these findings are discussed in terms of future research directions for prostate implants.
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Radiat Oncol Investig · Jan 1999
Comparative StudyIs there a role for short-term hormone use in the treatment of nonmetastatic prostate cancer?
We reviewed our institution's experience treating patients with prostate cancer with 3-dimensional conformal radiation therapy (3DCRT) and short-term adjuvant hormonal therapy to determine biochemical no evidence of disease (bNED) and clinical outcome compared with patients treated with 3DCRT alone. Between 4/1/89 and 11/30/94, 558 patients with clinically localized prostate cancer received treatment at Fox Chase Cancer Center (Philadelphia, Pa.); 484 patients were treated with 3DCRT alone (Group I); 74 patients were treated with 3DCRT and hormones (Group II). Five-year actuarial rates of bNED control, distant metastasis-free survival (DMFS), cause-specific survival (CSS), and overall survival (OS) were calculated for pretreatment PSA, Gleason score, T stage, use of hormones, treatment field size, age, and dose. ⋯ A trend towards significance was observed for different rates of DMFS between Group I and II (79% vs. 94%, P = 0.09). Patients with clinically localized prostate cancer with poor prognostic features (pretreatment PSA > or = 10 ng/ml, Gleason score > or = 7, and/or T2c or greater palpation stage) show improved rates of bNED control and a trend towards improved DMFS when treated with 3DCRT and short-term adjuvant hormones compared with 3DCRT alone. Long-term observation will be necessary to see if improvements in bNED control will translate into improvements in overall survival.
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Radiat Oncol Investig · Jan 1999
Comparative StudyResults of multifield conformal radiation therapy of nonsmall-cell lung carcinoma using multileaf collimation beams.
A five-field conformal technique with three-dimensional radiation therapy treatment planning (3-DRTP) has been shown to permit better definition of the target volume for lung cancer, while minimizing the normal tissue volume receiving greater than 50% of the target dose. In an initial study to confirm the safety of conventional doses, we used the five-field conformal 3-DRTP technique. We then used the technique in a second study, enhancing the therapeutic index in a series of 42 patients, as well as to evaluate feasibility, survival outcome, and treatment toxicity. ⋯ Pulmonary toxicity limited to Grades 1-2 occurred in 6.8% of the patients, and none developed > or =Grade 3 pulmonary toxicity. Patients with locally advanced NSCLC, who commonly have tumor volumes in excess of 200 cc, presenta challenge for adequate dose delivery without significant toxicity. Our five-field conformal 3-DRTP technique, which incorporates treatment planning by dose/volume histogram (DVH) was associated with minimal toxicity and may facilitate dose escalation to the gross tumor.
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Radiat Oncol Investig · Jan 1999
Comparative Study Clinical TrialHyperfractionated and accelerated-hyperfractionated radiotherapy for glioblastoma multiforme.
Because of promising radiobiological advantages allowing dose escalation and/or reduction of treatment time, hyperfractionated and accelerated-hyperfractionated radiotherapy (hf-rt, ahf-rt) were introduced as part of treatment of glioblastoma multiforme (gbm). In December 1988 we started a prospective study of hf-rt (total dose 78 Gy, two daily fractions of 1.3 Gy, interval between daily fractions 6 hr, treatment time 6 weeks, n = 34 patients). The results were compared with our previous regimen of conventionally fractionated radiotherapy (cf-rt: total dose 60 Gy, single dose 2 Gy, treatment time 6 weeks, n = 32 patients). ⋯ It demonstrated no improved survival. However, it showed that treatment time can be reduced by ahf-rt without loss of survival benefit or intolerable toxicity. A short radiotherapy course might be appropriate for many patients with gbm who are not suitable for rather aggressive investigational therapies.
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Radiat Oncol Investig · Jan 1999
Comparative StudyIs there a subset of patients with PSA > or = 20 ng/ml who do well after conformal beam radiotherapy?
To determine if there is a subgroup of patients with pretreatment PSA > or = 20 ng/ml with a favorable outcome after external beam radiation therapy. We analyzed retrospectively treatment outcomes of 129 patients with pretreatment PSA > or = 20 ng/ml treated in our department from 2/88-8/94. Median patient age was 70 years (range 51-89 years). ⋯ The bNED control was significantly higher for patients in Group I than those in Group II (58% vs. 23%, P = 0.0027). There appears to be a favorable subgroup of patients with PSA > or = 20 ng/ml where treating to doses over 73 Gy to the central axis is warranted (four-year bNED rate of 58%). However, because of the small patient numbers, these results will need to be validated with longer follow up.