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S Leibel

Publications and source records attributed to S Leibel.

At least 37 records · Page 2Linked to original sources

Isotope selection for patients undergoing prostate brachytherapy.

PURPOSE: Ultrasound-guided transperineal interstitial permanent prostate brachytherapy (TIPPB) is generally performed with either 103Pd or 125I. The use of 125I for low Gleason score tumors and 103Pd for higher Gleason scores has been suggested based on isotope dose rate and cell doubling time observed in in vitro studies. While many centers follow these isotope selection criteria, other centers have elected to use only a single isotope, regardless of Gleason score. No clinical data have been published comparing these isotopes. This study was undertaken to compare outcomes between 125I and 103Pd in a matched pair analysis for patients undergoing prostate brachytherapy. METHODS AND MATERIALS: Six hundred forty-eight consecutively treated patients with clinically confined prostate cancer underwent TIPPB between June 1992 and February 1997. Five hundred thirty-two patients underwent TIPPB alone, whereas 116 received pelvic external beam irradiation and TIPPB. Ninety-three patients received androgen deprivation therapy prior to TIPPB. The prescribed doses for TIPPB were 160 Gy for 125I (pre-TG43) and 120 Gy for 103Pd. Patients treated with combination therapy received 41.4 or 45 Gy (1.8 Gy/fraction) external beam irradiation followed by a 3- to 5-week break and then received either a 120-Gy 125I or a 90-Gy 103Pd implant. Until November 1994, all patients underwent an 125I implant after which the isotope selection was based on either Gleason score (Gleason score 2-5:125I; Gleason 5-8:103Pd) or isotope availability. A matched pair analysis was performed to assess any difference between isotopes. Two hundred twenty-two patients were matched according to Gleason score, prostate-specific antigen (PSA), and stage. PSA relapse-free survival (PSA-RFS) was calculated based on the American Society for Therapeutic Radiology and Oncology (ASTRO) Consensus Group definition of failure. Kaplan-Meier actuarial survival curves were compared to assess differences in pretreatment PSA and Gleason score. RESULTS: Univariate analysis of the 648 patients identified Gleason score, pretreatment PSA value, and stage as significant factors to predict PSA-RFS, but failed to identify isotope selection as significant. To address the significance of isotope selection further, the matched pair groupings were performed. The minimum follow-up for all 222 matched patients is 24 months with a median follow-up of 42 months (24-82). The actuarial PSA-RFS at 5 years for all 222 patients is 86.5%. One hundred eleven of the 222 matched patients received a 103Pd implant with an 87.1% 5-year PSA-RFS. The remaining 111 patients underwent a 125I implant with an 85.9% 5-year PSA-RFS (p = n.s.). Analysis of Gleason score subgroups 2-4, 5-6, and 7-9 failed to show any significant difference in PSA-RFS comparing isotopes. Pretreatment PSA subgroups of < or = 10 or > 10 ng/ml also failed to show any significant difference in PSA-RFS survival comparing isotopes. Analysis of postimplant dosimetry using dose delivered to 90% of the prostate volume (D90) did not identify any difference between the isotope groups. CONCLUSIONS: This matched pair analysis failed to demonstrate a difference for 125I and 103Pd in PSA-RFS for patients undergoing TIPPB. In addition, there were no observed advantages for either 125I or 103Pd in either the low or high Gleason score groups. This data indicates that the role of isotope selection for patients undergoing TIPPB requires further clarification.

Analysis of Variance↗

Urinary morbidity following ultrasound-guided transperineal prostate seed implantation.

PURPOSE: To assess the urinary morbidity experienced by patients undergoing ultrasound-guided, permanent transperineal seed implantation for adenocarcinoma of the prostate. METHODS AND MATERIALS: Between September 1992 and September 1997, 693 consecutive patients presented with a diagnosis of clinically localized adenocarcinoma of the prostate, and were treated with ultrasound-guided transperineal interstitial permanent brachytherapy (TPIPB). Ninety-three patients are excluded from this review, having received neoadjuvant antiandrogen therapy. TPIPB was performed with 125I in 165 patients and with 103Pd in 435 patients. Patients treated with implant alone received 160 Gy with 125I (pre TG43) or 120 Gy with 103Pd. One hundred two patients received preimplant, pelvic external beam radiation (XRT) to a dose of either 41.4 or 45 Gy because of high-risk features including PSA > or = 10 and/or Gleason score > or = 7. Combined modality patients received 120 Gy and 90 Gy, respectively for 125I or 103Pd. All patients underwent postimplant cystoscopy and placement of an indwelling Foley catheter for 24-48 h. Follow-up was at 5 weeks after implant, every 3 months for the first 2 years, and then every 6 months for subsequent years. Patients completed AUA urinary symptom scoring questionnaires at initial consultation and at each follow-up visit. Urinary toxicity was classified by the RTOG toxicity scale with the following adaptations; grade 1 urinary toxicity was symptomatic nocturia or frequency requiring none or minimal medical intervention such as phenazopyridine; grade 2 urinary toxicity was early obstructive symptomatology requiring alpha-blocker therapy; and grade 3 toxicity was considered that requiring indwelling catheters or posttreatment transurethral resection of the prostate for symptom relief. Log-rank analysis and Chi-square testing was performed to assess AUA score, prostate size, isotope selection, and the addition of XRT as possible prognosticators of postimplant urinary toxicity. The prostate volume receiving 150% of the prescribed dose (V150) was studied in patients to assess its correlation with urinary toxicity. RESULTS: Median follow-up was 37 months (range 6-68). Within the first 60 days, 37.3% of the patients reported grade 1 urinary toxicity, 41% had grade 2, and 2.2% had grade 3 urinary toxicity. By 6 months, 21.4% still reported grade 1 urinary toxicity, whereas 12.8% and 3% complained of grade 2 and 3 urinary difficulties, respectively. Patients with a preimplant AUA score < or = 7 had significantly less grade II toxicity at 60 days compared to those with an AUA score of >7 (32% vs. 59.2%, respectively, p = 0.001). Similarly, prostatic volumes < or = 35 cc had a significantly lower incidence of grade II urinary toxicity (p = 0.001). There was no difference in toxicity regarding the isotope used (p = 0.138 at 60 days, p = 0.45 at 6 months) or the addition of preimplant XRT (p = 0.069 at 60 days, p = 0.84 at 6 months). Twenty-eight patients (4.7%) underwent TURP after 3 isotope half-lives for protracted obstructive symptoms. Five of these men (17%) developed stress incontinence following TURP, but all patients experienced relief of their obstructive symptoms without morbidity at last follow-up. The percent of the prostate receiving 150% of the prescribed dose (V150) did not predict urinary toxicity. CONCLUSIONS: TPIPB is well tolerated but associated with mild to moderate urinary morbidity. Pretreatment prostatic volume and AUA scoring were shown to significantly predict for grade 2 toxicity while the use of preimplant, pelvic XRT and isotope selection did not. Patients undergoing TURP for protracted symptoms following TPIPB did well with a 17% risk of developing stress incontinence. V150 did not help identify patients at risk for urinary morbidity. As transperineal prostate implantation is used more frequently the associated toxicities and the definition of possible pretreatment prognostic factors is necessary to

Aged↗

Procarbazine, lomustine, and vincristine (PCV) chemotherapy for anaplastic astrocytoma: A retrospective review of radiation therapy oncology group protocols comparing survival with carmustine or PCV adjuvant chemotherapy.

PURPOSE: To determine any differences in outcome for patients with anaplastic astrocytoma (AA) treated with adjuvant carmustine (BCNU) versus procarbazine, lomustine, and vincristine (PCV) chemotherapy. MATERIALS AND METHODS: The Radiation Therapy Oncology Group (RTOG) database was reviewed for patients with newly diagnosed AA treated according to protocols that included either BCNU or PCV adjuvant chemotherapy. All patients were treated with radiation therapy. The outcome analysis included overall survival, taking into account patient age, extent of resection, Karnofsky performance status (KPS), and treatment group (BCNU v PCV). Stratified and nonstratified Cox proportional hazards models were used, as well as an analysis using matched cases between the groups. RESULTS: A total of 257 patients were treated with BCNU according to RTOG protocols 70-18, 83-02, and 90-06; 175 patients were treated with PCV according to RTOG protocol 94-04. All pretreatment characteristics except KPS were well balanced by treatment group; 61% of the BCNU group had a KPS of 90 to 100 compared with 73% of the PCV group (P =.0075). No statistically significant difference in survival was observed in any age group or by KPS or extent of surgery. The stratified analysis also showed no trends for improved survival by treatment group (P =. 40). The Cox model identified only age, KPS, and extent of surgery as important variables influencing survival, not treatment group. Matching cases between groups using age, KPS, and surgery resulted in 133 matched pairs. No difference in survival was observed (P =. 41). In a Cox model in which each matched pair is a strata, there was no difference between groups (P =.20). CONCLUSION: Using this retrospective analysis, there does not seem to be any survival benefit to PCV chemotherapy. Future phase III studies for patients with AA may need to consider whether BCNU or PCV is used in the control arm.

Adult↗

Planning, delivery, and quality assurance of intensity-modulated radiotherapy using dynamic multileaf collimator: a strategy for large-scale implementation for the treatment of carcinoma of the prostate.

PURPOSE: To improve the local control of patients with adenocarcinoma of the prostate we have implemented intensity modulated radiation therapy (IMRT) to deliver a prescribed dose of 81 Gy. This method is based on inverse planning and the use of dynamic multileaf collimators (DMLC). Because IMRT is a new modality, a major emphasis was on the quality assurance of each component of the process and on patient safety. In this article we describe in detail our procedures and quality assurance program. METHODS AND MATERIALS: Using an inverse algorithm, we have developed a treatment plan consisting five intensity-modulated (IM) photon fields that are delivered with DMLC. In the planning stage, the planner specifies the number of beams and their directions, and the desired doses for the target, the normal organs and the "overlap" regions. Then, the inverse algorithm designs intensity profiles that best meet the specified criteria. A second algorithm determines the leaf motion that would produce the designed intensity pattern and produces a DMLC file as input to the MLC control computer. Our quality assurance program for the planning and treatment delivery process includes the following components: 1) verification of the DMLC field boundary on localization port film, 2) verification that the leaf motion of the DMLC file produces the planned dose distribution (with an independent calculation), 3) comparison of dose distribution produced by DMLC in a flat phantom with that calculated by the treatment planning computer for the same experimental condition, 4) comparison of the planned leaf motions with that implemented for the treatment (as recorded on the MLC log files), 5) confirmation of the initial and final positions of the MLC for each field by a record-and-verify system, and 6) in vivo dose measurements. RESULTS: Using a five-field IMRT plan we have customized dose distribution to conform to and deliver 81 Gy to the PTV. In addition, in the overlap regions between the PTV and the rectum, and between the PTV and the bladder, the dose is kept within the tolerance of the respective organs. Our QA checks show acceptable agreement between the planned and the implemented leaf motions. Correspondingly, film and TLD dosimetry indicates that doses delivered agrees with the planned dose to within 2%. As of September 15, 1996, we have treated eight patients to 81 Gy with IMRT. CONCLUSION: For complex planning problems where the surrounding normal tissues place severe constraints on the prescription dose, IMRT provides a powerful and efficient solution. Given a comprehensive and rigorous quality-assurance program, the intensity-modulated fields can be efficaciously and accurately delivered using DMLC. IMRT treatment is now ready for routine implementation on a large scale in our clinic.

Adenocarcinoma↗

Promising survival with three-dimensional conformal radiation therapy for non-small cell lung cancer.

PURPOSE: Local failure is a major obstacle to the cure of locally advanced non small-cell lung cancer. Three-dimensional conformal radiation therapy (3-DCRT) selects optimal treatment parameters to increase dose to tumor and reduce normal tissue dose, potentially representing an enhancement of the therapeutic ratio of radiation therapy for lung cancer. We performed this analysis of 45 non-small cell lung cancer patients treated with 3-DCRT alone, to evaluate the ability of computer derived lung dose volume histograms to predict serious pulmonary toxicity, to assess the feasibility of this approach, and to examine the resulting survival. METHODS: There were 28 males (62%) and 17 females (38%). The median age was 65 (range: 38-82). Tumor stage was Stage I/II in 13%, IIIa in 42%, and IIIb in 44%. The histology was squamous in 44%, adenocarcinoma in 36%, and other non-small cell histologies in the others. Only 47% of patients. had combined favorable prognostic factors (i.e. KPS < or = 80, and < or = 5% wt. loss). The median dose of radiation to gross disease was 70.2 Gy (range: 52.2-72 Gy) delivered in fractions of 1.8 Gy, 5 days per week. RESULTS: Seven patients did not complete 3-DCRT due to disease progression outside the port. Follow-up data are mature: the median follow up of the 6 survivors is 43.5 months (35-59). Thoracic progression occurred in 46%. Median survival (all 45 patients.) is 15.7 months and survival is 32% at 2 years and 12% at 59 months. Pulmonary toxicity > or = grade 3 occurred in 9% of patients. Dose volume histograms were available in 31 patients and showed a correlation between risk of pulmonary toxicity and indices of dose to lung parenchyma. Grade 3 or higher pulmonary toxicity occurred in 38% (3/8) of patients with > 30% of lung volume receiving > or = 25 Gy, versus 4% (1/23) of patients with < or = 30% lung receiving > or = 25 Gy (P = 0.04). Grade 3 or higher pulmonary toxicity occurred in 29% (4/14) of patients with a predicted pulmonary normal tissue complication probability of 12% or higher versus 0% (0/17) in patients with a predicted probability of less than 12% (P = 0.03). CONCLUSIONS: Despite adverse prognostic criteria median survival is encouraging and may be higher than some combined modality approaches. Dose volume histogram parameters may be useful to determine the maximum dose for individual patients and thereby permit avoidance of toxicity.

Adult↗