Biomedical subjects

S Leibel

Publications and source records attributed to S Leibel.

At least 19 recordsLinked to original sources

PubMed2001

Pretreatment nomogram for predicting freedom from recurrence after permanent prostate brachytherapy in prostate cancer.

OBJECTIVES: To develop a prognostic nomogram to predict the freedom from recurrence for patients treated with permanent prostate brachytherapy for localized prostate cancer. METHODS: We performed a retrospective analysis of 920 patients treated with permanent prostate brachytherapy between 1992 and 2000. The clinical parameters included clinical stage, biopsy Gleason sum, pretreatment prostate-specific antigen (PSA) value, and administration of external beam radiation. Patients who received neoadjuvant androgen deprivation therapy were excluded. Failure was defined as any post-treatment administration of androgen deprivation, clinical relapse, or biochemical failure, defined as three PSA rises. Patients with fewer than three PSA rises were censored at the time of the first PSA rise. Data from two outside institutions served as validation. RESULTS: A nomogram that predicts the probability of remaining free from biochemical recurrence for 5 years after brachytherapy without adjuvant hormonal therapy was developed using Cox proportional hazards regression analysis. External validation revealed a concordance index of 0.61 to 0.64, and calibration of the nomogram suggested confidence limits of +5% to -30%. CONCLUSIONS: The pretreatment nomogram we developed may be useful to physicians and patients in estimating the probability of successful treatment 5 years after brachytherapy for clinically localized prostate cancer.

Adenocarcinoma↗

PubMed2001

Local detection of prostate cancer by positron emission tomography with 2-fluorodeoxyglucose: comparison of filtered back projection and iterative reconstruction with segmented attenuation correction.

BACKGROUND: To compare filtered back projection (FBP) and iterative reconstruction with segmented attenuation correction (IRSAC) in the local imaging of prostate cancer by positron emission tomography with 2-fluorodeoxyglucose (FDG-PET). METHODS: We retrospectively identified 13 patients with primary (n=7) or recurrent (n=6) prostate cancer who had increased uptake in the prostate on FDG-PET performed without urinary catheterization, contemporaneous biopsy confirming the presence of active tumor in the prostate, and correlative cross-sectional imaging by MRI (n=8) or CT (n=5). FDG-PET images were reconstructed by FBP and IRSAC. Two independent nuclear medicine physicians separately rated FBP and IRSAC images for visualization of prostatic activity on a 4-point scale. Results were compared using biopsy and cross-sectional imaging findings as the standard of reference. RESULTS: IRSAC images were significantly better that FBP in terms of visualization of prostatic activity in 12 of 13 patients, and were equivalent in 1 patient (p<0.001, Wilcoxon signed ranks test). In particular, 2 foci of tumor activity in 2 different patients seen on IRSAC images were not visible on FBP images. In 11 patients who had a gross tumor mass evident on cross-sectional imaging, there was good agreement between PET and cross-sectional anatomic imaging with respect to tumor localization. CONCLUSIONS: In selected patients, cancer can be imaged within the prostate using FDG-PET, and IRSAC is superior to FBP in image reconstruction for local tumor visualization.

Aged↗

PubMed2000

The definition of biochemical failure in patients treated with definitive radiotherapy.

PURPOSE: The American Society for Therapeutic Radiology and Oncology (ASTRO) published a definition for biochemical failure following treatment of prostate cancer. Others have noted difficulties with interpreting this definition and recommended modifications to accommodate special recurrence patterns. We have compared various modifications to the original ASTRO definition on our series of 1213 patients treated with transperineal permanent prostate brachytherapy. METHODS AND MATERIALS: The ASTRO modifications we considered adjusted for (1) early censoring of nonrecurrent patients with rising prostate-specific antigen levels (PSA), (2) cumulative rather than consecutive rises (without a decrease) as evidence of recurrence, (3) both of the above, and (4) waiting 2 years before data analysis. The Kaplan-Meier method was used to compute the effects on recurrence rate for patients treated with and without neoadjuvant hormones. RESULTS: With the original ASTRO definition, freedom from recurrence in our series of men who did not receive neoadjuvant hormones was 83% at 4 years. All of the modifications considered had statistically insignificant effects on freedom from recurrence rates, varying from 80% to 83% at 4 years. Patients treated with neoadjuvant hormones also showed very little sensitivity to the recurrence definition employed. CONCLUSION: Early censoring of equivocal patients and counting cumulative rather than consecutive rises in PSA (without a decrease) had little empiric effect on the ASTRO recurrence rates. However, we favor the addition of both these modifications to the ASTRO definition on conceptual grounds for evaluating patients following any modality (radiation or surgery), whereby a trend over multiple PSA values is used to judge failure.

Brachytherapy↗

PubMed2000

Towards multidimensional radiotherapy (MD-CRT): biological imaging and biological conformality.

PURPOSE: The goals of this study were to survey and summarize the advances in imaging that have potential applications in radiation oncology, and to explore the concept of integrating physical and biological conformality in multidimensional conformal radiotherapy (MD-CRT). METHODS AND MATERIALS: The advances in three-dimensional conformal radiotherapy (3D-CRT) have greatly improved the physical conformality of treatment planning and delivery. The development of intensity-modulated radiotherapy (IMRT) has provided the "dose painting" or "dose sculpting" ability to further customize the delivered dose distribution. The improved capabilities of nuclear magnetic resonance imaging and spectroscopy, and of positron emission tomography, are beginning to provide physiological and functional information about the tumor and its surroundings. In addition, molecular imaging promises to reveal tumor biology at the genotype and phenotype level. These developments converge to provide significant opportunities for enhancing the success of radiotherapy. RESULTS: The ability of IMRT to deliver nonuniform dose patterns by design brings to fore the question of how to "dose paint" and "dose sculpt", leading to the suggestion that "biological" images may be of assistance. In contrast to the conventional radiological images that primarily provide anatomical information, biological images reveal metabolic, functional, physiological, genotypic, and phenotypic data. Important for radiotherapy, the new and noninvasive imaging methods may yield three-dimensional radiobiological information. Studies are urgently needed to identify genotypes and phenotypes that affect radiosensitivity, and to devise methods to image them noninvasively. Incremental to the concept of gross, clinical, and planning target volumes (GTV, CTV, and PTV), we propose the concept of "biological target volume" (BTV) and hypothesize that BTV can be derived from biological images and that their use may incrementally improve target delineation and dose delivery. We emphasize, however, that much basic research and clinical studies are needed before this potential can be realized. CONCLUSIONS: Whereas IMRT may have initiated the beginning of the end relative to physical conformality in radiotherapy, biological imaging may launch the beginning of a new era of biological conformality. In combination, these approaches constitute MD-CRT that may further improve the efficacy of cancer radiotherapy in the new millennium.

Fluorodeoxyglucose F18↗

PubMed2000

The role of external beam irradiation in patients undergoing prostate brachytherapy.

6. From this cohort, a matched-pair analysis was performed to better assess the role of EBT and TIPPB (n = 215). PSA relapse-free survival was based on the American Society for Therapeutic Radiology and Oncology Consensus Panel definition. Kaplan-Meier actuarial survival curves were compared to assess various prognostic factors. The median follow-up for all 215 matched patients was 44 months (range, 24-81) with an actuarial PSA relapse-free survival (RFS) at 5 years of 81.1%. Patients treated with EBT and TIPPB had a 5-year PSA RFS of 83.5% whereas patients treated with TIPPB only had a 5-year PSA RFS of 79.4% (p = 0.715)10 ng/ml. Risk group analysis combining PSA, Gleason score, and stage failed to identify any risk group for which the addition of EBT was significant. Analysis of postimplant dosimetry using the dose to 90% of the prostate volume (D90) failed to distinguish any difference between groups. A significant advantage for combining EBT and TIPPB could not be demonstrated in this retrospective matched-pair analysis. These data indicate that the role and rationale of combined treatment in prostate brachytherapy requires better clarification, with a prospective randomized trial.

Journal Article↗

PubMed2000

Examining the role of neoadjuvant androgen deprivation in patients undergoing prostate brachytherapy.

PURPOSE: To assess the role of neoadjuvant androgen deprivation (NAAD) and transperineal interstitial permanent prostate brachytherapy (TIPPB) using a matched-pair analysis selected from a large cohort of patients undergoing TIPPB. PATIENTS AND METHODS: Six hundred twelve consecutive patients with clinically confined prostate cancer were treated between June 1992, and January 1997, with permanent ultrasound-guided TIPPB with either palladium-103 or iodine-125 as monotherapy or combined with external radiation. Patients with prostate glands >/= 60 g underwent treatment with NAAD before TIPPB to reduce the prostate volume (n = 163). The median duration of NAAD was 3.4 months before TIPPB (range, 1 to 8 months). To assess the benefit of NAAD, a matched-pair analysis was performed. The American Society of Therapeutic Radiology and Oncology Consensus Group definition of prostate-specific antigen (PSA) relapse-free survival (RFS) was used with the added caveat of an absolute increase of >/= 1.0 ng/mL. Differences in pretreatment PSA, Gleason scores, and stage were analyzed by Kaplan-Meier curves and the log-rank test. RESULTS: Two hundred sixty-three patients were matched, with a median follow-up duration of 46 months (range, 24 to 76 months). The actuarial 5-year PSA-RFS rate for all 263 patients is 86.5%. The 5-year PSA-RFS rate for patients treated with NAAD and TIPPB was 87.1% compared with 86.9% for those treated with TIPPB only (P =.935). Subgroup analysis by Gleason score groupings, pretreatment PSA, or stage of disease failed to identify any factors for which androgen ablation was beneficial. CONCLUSION: We were unable to identify any improvement with the addition of NAAD to TIPPB in patients with localized prostate cancer in this retrospective matched-pair analysis. Furthermore, there was no subset for which the addition of NAAD was found to be beneficial. Clarification of the role and duration of NAAD in patients with early-stage prostate cancer will require prospective data.

Adenocarcinoma↗

PubMed2000