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Eric M Horwitz

Publications and source records attributed to Eric M Horwitz.

At least 55 records · Page 3Linked to original sources
PubMed2003

Does short-term androgen deprivation substitute for radiation dose in the treatment of high-risk prostate cancer?

PURPOSE: Randomized trials have corroborated the clinical benefit of adding androgen deprivation (AD) to radiotherapy (RT) in the treatment of high-risk prostate cancer. Another competing strategy is to escalate the RT dose using three-dimensional conformal RT (3D-CRT). In this analysis, we asked whether the addition of short-term AD (STAD) ( 20 ng/mL, Gleason score 8-10, or T3-4) prostate cancer is an effective substitute for dose escalation. METHODS AND MATERIALS: Between March 1, 1990 and November 30, 1998, 296 high-risk prostate cancer patients were treated with 3D-CRT alone (n = 206) or in combination with STAD (n = 90). The patient characteristics were median age 68 years, median follow-up 58 months, pretreatment initial prostate-specific antigen 21.8 ng/mL, RT dose 75 Gy, STAD duration 3 months, and time off STAD 64 months. The impact of STAD with respect to dose was examined using univariate analysis for dose ranges of <75 Gy and >or=75 Gy. Stepwise Cox proportional hazards regression multivariate analysis was performed to determine independent correlates of freedom from biochemical failure (bNED), freedom from distant metastasis (FDM), and overall survival. In a separate matched-pair analysis (n = 44 per group), those treated to <75 Gy + STAD (Group A) were compared with those who received >or=75 Gy alone (Group B). RESULTS: On univariate analysis, the addition of STAD had no impact on bNED, FDM, or overall survival in either dose group. On multivariate analysis, initial prostate-specific antigen level, palpation T stage, and RT dose were significant correlates of bNED. For FDM and overall survival, the significant covariates were palpation T stage and Gleason score, respectively. Finally, in matched-pair analysis, the higher RT dose group had a significantly greater bNED rate at 5 years (Group A 35% vs. Group B 57%, p = 0.0190). CONCLUSION: Our data suggest that STAD, as used here (median 3 months), is not a substitute for RT dose in the treatment of high-risk prostate cancer. RT dose is an essential element in the treatment of high-risk prostate cancer.

Aged↗
PubMed2003

Radiation therapy dose escalation for prostate cancer: a rationale for IMRT.

The response of prostate cancer to radiation was well-documented in the pre-PSA era. Large palpable tumors resolved within months of treatment with relatively modest radiation doses of 64-70 Gy. The use of PSA-based failure as an endpoint, however, has made it clear that cure rates were much lower than appreciated. While doses in this range are still widely used today, data from retrospective, sequential prospective and now randomized studies indicate that for patients with intermediate-to-high risk disease, doses above 70 Gy are associated with a significant reduction in biochemical failure. The use of 3D-conformal radiotherapy to escalate radiation dose has resulted in modest increases in rectal and bladder toxicity. The application of intensity modulated radiotherapy methods allows for greater sparing of the surrounding normal tissues and, hence, the potential to further escalate dose. The results of dose escalation, the ability of IMRT to reduce rectal and bladder exposure to high radiation doses and the use of new imaging methods to more accurately target the prostate are described.

Humans↗
PubMed2003

Biochemical failure as a determinant of distant metastasis and death in prostate cancer treated with radiotherapy.

PURPOSE: Biochemical failure (BF), defined by a rising prostate-specific antigen (PSA) profile, is an early surrogate of treatment failure. However, little evidence is available to show that BF is associated with death for patents with prostate cancer treated with radiotherapy. We examined the relationship between BF and death from prostate cancer. METHODS AND MATERIALS: A total of 942 patients were treated between 1987 and 1998 with external beam radiotherapy who had sufficient PSA determinations in follow-up for the analyses described. The median radiation dose was 72 Gy, median PSA was 9.9 ng/mL, and median follow-up was 73 months. The American Society for Therapeutic Radiology and Oncology consensus definition was used to define BF. Kaplan-Meier calculations were from the start of radiotherapy. Cox proportional hazards regression multivariate analyses were used to investigate the association of BF (time-dependent variable) and other factors to distant metastasis (DM), cause-specific death (CSD), and overall death (OD). The year of treatment was included in some of the multivariate analyses to correct for potential unknown factors that may have occurred during the years of the study, such as stage migration. RESULTS: BF was observed in 316 patients (34%), and 66 (7%) experienced DM, 32 (3%) died of prostate cancer, and 230 (24%) died overall during the study period. The Kaplan-Meier 5-year rate estimates from the start of treatment for BF, DM, CSD, and OD were 38%, 6%, 3%, and 13%, respectively. All patients with DM had BF. In multivariate analyses, BF was associated with DM and CSD, but not OD. The inclusion of the year of treatment did not alter these relationships. CONCLUSION: BF, as a time-dependent covariate, was the strongest determinant of DM and was also very significantly related to CSD. The inclusion of the year of treatment had little effect on these associations. Longer follow-up is needed to determine conclusively the relationship of BF to OD.

Aged↗
PubMed2003

The Gleason score shift: score four and seven years ago.

PURPOSE: There is some evidence that Gleason scores (GS) have shifted over time, although documentation of the extent to which this has occurred and its clinical significance is sparse. METHODS AND MATERIALS: Three types of analyses were performed to characterize the GS shift. First, the time-related changes in GS, T-stage category, and PSA for all 983 patients treated with conformal radiotherapy at our institution were examined between 1992 and 1997. Then a matched-pair analysis of patients treated without androgen deprivation was implemented. Patients were matched for grouped GS, grouped PSA, T category, and grouped radiation dose; 242 patients (Cohort 1) treated between 1992 and 1994 were compared to 242 patients treated between 1995 and 1997 (Cohort 2). Follow-up for each patient in Cohort 1 was truncated to match the length of follow-up for his counterpart in Cohort 2 (median follow-up 42 vs. 47 months). The ASTRO consensus definition of a rising PSA was used. Finally, the pathology slides of 106 patients treated with radiotherapy at another institution between 1987 and 1993 underwent a blind second review by one of the study pathologists (P.T.) in 1998. RESULTS: The percentages of prostate cancer patients treated with radiotherapy at our institution from 1992 to 1994 vs. 1995 to 1997 were GS 2-5: 49% vs. 16%, GS 6: 27% vs. 59%, GS 7: 20% vs. 19%, and GS > or =8: 8.3% vs. 6%. There was no clear difference in T category over time with 92-96% having T1-T2 disease. The percentage of patients with a PSA < or = 10 ng/mL rose rapidly from 35% in 1992 to 63% in 1994. In corroboration of these findings, the pathologic review of specimens from 106 patients at another institution yielded changes between the initial reading to the recent reading of 50% to 6% for GS 2-5, 22% to 31% for GS 6, 16% to 25% for GS 7, and 12% to 25% for GS 8-10 (p < 0.0001). From the matched-pair analysis, 5-year Kaplan-Meier bNED rates were 68% and 82% (p = 0.03) favoring Cohort 2. CONCLUSIONS: During the study period, pretreatment PSA values declined and T category remained stable; yet, GS increased. Upgrading of GS would be expected to lead to an improvement in outcome for all GS groups because of the Will Rogers effect, which explains in part the results of the matched-pair analysis. The GS shift confounds retrospective series spanning the 1990s.

Humans↗
PubMed2003

Validation of a treatment policy for patients with prostate specific antigen failure after three-dimensional conformal prostate radiation therapy.

BACKGROUND: The objective of this report was to present an outcomes validation for the Fox Chase Cancer Center (FCCC) management policy for patients who demonstrate prostate specific antigen (PSA) failure after receiving three-dimensional conformal radiation therapy (3DCRT). METHODS: Eligible patients included 248 men with T1-T3N0M0 prostate carcinoma who demonstrated PSA failure (according to the American Society for Therapeutic Radiology and Oncology definition) after completing definitive 3DCRT alone or with androgen deprivation (AD) therapy between May 1989 and November 1997. The primary endpoint evaluated was freedom from distant metastasis (FDM). The secondary endpoints evaluated included cause specific survival (CSS) and overall survival (OS). The variables evaluated in the multivariate analyses (MVA) included initial PSA, Gleason score, T classification, dose, PSA nadir, time to PSA failure, PSA doubling time (PSADT), initial use of AD therapy, and the use of AD therapy upon PSA failure. RESULTS: The 5-year FDM, CSS, and OS rates for the entire group were 76%, 92%, and 76%, respectively. It was found that four variables were independent predictors of FDM: Gleason score (P = 0.0039), PSA nadir (P = 0.0001), PSADT (P = 0.0001), and the use of AD on PSA failure (P = 0.0001). One hundred forty-eight men demonstrated a PSADT < 12 months. AD therapy was started in 59 men, and 89 men refused AD therapy and were observed. The use of AD therapy was associated with a significant improvement in the 5-year FDM rate (57% vs. 78%; P = 0.0026). In the group of men with PSADT < 12 months, the median time to distant failure was significantly longer in the men who received AD therapy (6 months vs. 25 months; P = 0.02). Of the 100 men with a PSADT > or = 12 months, 89 men were observed, and 11 men received AD therapy. There was no improvement in the 5-year FDM rate with the use of AD therapy compared with observation (88% vs. 92%, respectively; P = 0.74). CONCLUSIONS: The current results validate the use of PSADT as an indicator of patients who may be observed expectantly or treated with AD therapy for PSA failure after 3DCRT. Prospective trials are needed to define further the optimal treatment for these patients.

Algorithms↗
PubMed2003

Late morbidity profiles in prostate cancer patients treated to 79-84 Gy by a simple four-field coplanar beam arrangement.

PURPOSE: To describe the frequency and magnitude of late GI and GU morbidity in prostate cancer patients treated to high dose levels with a simple three-dimensional conformal technique. METHODS AND MATERIALS: A total of 156 intermediate- and high-risk patients were treated between January 1, 1992 and February 28, 1999 with a simple four-field three-dimensional conformal technique to 79-84 Gy. All patients were treated with a four-field conformal technique; the prostate received 82 Gy and the seminal vesicles and periprostatic tissue 46 Gy. GI and GU toxicity was scored according to the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer Late Morbidity Grading Scale and compared using Kaplan-Meier estimates. RESULTS: The late Grade 2 GI complication rate was 9% and 38% at 3 years for patients treated with and without rectal blocking, respectively (p = 0.0004). No Grade 3 late GI complications developed. The rate of Grade 2 late GU complications was 5%, 8%, and 12% at 12, 24, and 36 months, respectively. The Grade 3 late GU complication rate was 2% at 36 months. These differences were not statistically significant. CONCLUSION: The treatment method described is a simple four-field conformal technique that can be easily implemented in the general radiation community. A dose of 79-84 Gy can be safely delivered to the prostate, with a 9% rate of late Grade 2 GI, 12% rate of late Grade 2 GU, and 2% rate of late Grade 3 GU complications.

Digestive System↗
PubMed2003

Free prostate-specific antigen improves prostate cancer detection in a high-risk population of men with a normal total PSA and digitalrectal examination.

OBJECTIVES: Uncertainty exists regarding optimal prostate cancer screening parameters for high-risk populations. The purpose of this study is to report the use of percent free prostate-specific antigen (PSA) as an indication for biopsy in men at increased risk for developing prostate cancer who have a normal digital rectal examination (DRE) and total PSA level between 2 and 4 ng/mL. METHODS: African-American men and men with at least one first-degree relative with prostate cancer are eligible for enrollment into the Prostate Cancer Risk Assessment Program (PRAP) at our institution. Between October 1996 and April 2002, 310 asymptomatic high-risk men with no history of prostate cancer, benign prostatic hyperplasia (BPH), or prostatic intraepithelial neoplasia (PIN) were screened in the PRAP with DRE and total PSA. Percent free PSA was obtained in men with a total PSA between 2 and 10 ng/mL. Men with a normal DRE and total PSA between 2 and 4 ng/mL were advised to undergo transrectal ultrasound-guided (TRUS) biopsies of the prostate if the percent free PSA was less than 27%. Other indications for biopsy included an abnormal DRE or a total PSA greater than 4 ng/mL. The primary endpoint evaluated was prostate cancer detection in high-risk men with a benign prostate examination, a normal total PSA between 2 and 4 ng/mL, and percent free PSA less than 27%. RESULTS: Of the 310 men, 174 (56%) were African American and 202 (65%) had at least one first-degree relative with prostate cancer. Sixty-two of the 310 men were referred for prostate biopsy, and 40 of 62 had biopsy performed. Twenty-one of 40 men were diagnosed with prostate cancer for a cancer detection rate of 53% in all men undergoing biopsy and an overall cancer detection rate of 6.8% in this high-risk population. Thirty-seven high-risk men (median age 54 years) with a total PSA level between 2 and 4 ng/mL (median 2.7 ng/mL) and a normal DRE were found to have a percent free PSA level of less than 27% (median 16%, range 8% to 25%). Twenty-three of these 37 men (62%) proceeded with the recommended prostate biopsy. Prostatic adenocarcinoma was diagnosed in 12 of 23 men for a cancer detection rate of 52% in men undergoing biopsy and 32% in all men with a normal DRE, a total PSA between 2 and 4 ng/mL, and a percent free PSA less than 27%. All positive biopsies demonstrated clinically significant Gleason score 6 or 7 disease. In all men electing radical prostatectomy, bilateral organ-confined disease (pT2bN0M0) was confirmed. CONCLUSIONS: In this unique population of men at high risk for prostate cancer, a percent free PSA of less than 27% was found to be useful for detecting early-stage but clinically significant cancers in men with a total PSA value between 2 and 4 ng/mL and normal DRE findings.

Biopsy, Needle↗
PubMed2003

Positive prostate biopsy laterality and implications for staging.

OBJECTIVES: To examine the effect of including positive prostate biopsy information in palpation staging (2002 system) and the influence of this information on freedom from biochemical failure (bNED). Prostate biopsy laterality status (unilateral versus bilateral positive) is part of clinical staging using American Joint Commission on Cancer criteria, but is rarely used. METHODS: From April 1, 1989 to September 30, 1999, 1038 patients with palpable T1-T3Nx-0M0 prostate cancer were treated with three-dimensional conformal radiotherapy alone. Kaplan-Meier bNED curves were compared using the log-rank test. The Cox proportional hazards regression model of bNED was used for multivariate analysis. RESULTS: The median follow-up was 46 months. The proportion of patients with bilateral positive biopsies by palpation category T1c was 24%, by T2a was 17%, by T2b was 26%, by T2c was 65%, and by T3 was 53%. No statistically significant difference was noted in bNED on the basis of biopsy laterality status for the palpation T stages T1c, T2a, T2b, or T3. A statistically significant difference in the 5-year bNED in the T2c stage was found; those with unilateral positive biopsies fared worse (46% versus 74%, respectively, P = 0.04). CONCLUSIONS: Inclusion of positive biopsy laterality status into clinical staging causes stage migration without reflecting a change in outcome and should not be used.

Aged↗
PubMed2003

Mindless or mindful? Radiation oncologists' perspectives on the evolution of prostate cancer treatment.

The evolution of radiation therapy treatment for prostate cancer has been striking over the last 10 years. Advances in brachytherapy (BT), external beam radiotherapy (EBRT), and the combination of EBRT + BT have led to improved biochemical and clinical results. This article describes these advances in the context of the treatment decision process. Key to this process is the assignment of patient risk, which is based on the results of conventional radiation dose and techniques. Using the 1992 AJCC palpation staging system, Gleason score, and pretreatment prostate-specific antigen, two different risk assessment algorithms were compared. Both gave comparable approximations of risk, although the single factor high-risk model was superior in differentiating those patients with the highest probability of failing treatment after radiotherapy. Such criteria are the foundation for treatment selection. Objective findings support BT alone or EBRT alone for low-risk patients, high-dose EBRT or EBRT + BT for intermediate-risk patients, and EBRT + androgen deprivation for high-risk patients. In summary, advances in radiation oncology have led to significant gains in prostate cancer control. Clinical prognostic factor-based patient selection is central to the optimization of outcome.

Brachytherapy↗
PubMed2003

Brachytherapy for prostate cancer: follow-up and management of treatment failures.

The use of prostate brachytherapy for the treatment of early-stage, low-grade, low-volume carcinoma of the prostate continues to rise. Given the prolonged natural history of these early lesions, treatment failures may take many years or even a decade or more before becoming clinically evident. It is therefore likely that as the brachytherapy data mature, clinicians will be asked to help manage a potentially large cohort of men who have failed this local therapy--a scenario that will provide a number of unique challenges for the treatment of the disease and the management of the lower urinary tract. This article offers a contemporary review and suggestions with regard to the follow-up of patients who have undergone prostate brachytherapy, including low-dose rate permanent implants and high-dose rate temporary implants for the management of localized prostate cancer. In addition, current controversies in defining biochemical failure following radioactive implantation--including important data regarding the "prostate-specific antigen bounce" phenomenon--are discussed. Finally, a comprehensive review of the management of local recurrence following brachytherapy is offered.

Biopsy↗
PubMed2003

Impact of target volume coverage with Radiation Therapy Oncology Group (RTOG) 98-05 guidelines for transrectal ultrasound guided permanent Iodine-125 prostate implants.

PURPOSE: Despite the wide use of permanent prostate implants for the treatment of early stage prostate cancer, there is no consensus for optimal pre-implant planning guidelines that results in maximal post-implant target coverage. The purpose of this study was to compare post-implant target volume coverage and dosimetry between patients treated before and after Radiation Therapy Oncology Group (RTOG) 98-05 guidelines were adopted using several dosimetric endpoints. MATERIALS AND METHODS: Ten consecutively treated patients before the adoption of the RTOG 98-05 planning guidelines were compared with ten consecutively treated patients after implementation of the guidelines. Pre-implant planning for patients treated pre-RTOG was based on the clinical target volume (CTV) defined by the pre-implant TRUS definition of the prostate. The CTV was expanded in each dimension according to RTOG 98-05 and defined as the planning target volume. The evaluation target volume was defined as the post-implant computed tomography definition of the prostate based on RTOG 98-05 protocol recommendations. Implant quality indicators included V(100), V(90), V(100), and Coverage Index (CI). RESULTS: The pre-RTOG median V(100), V(90), D(90), and CI values were 82.8, 88.9%, 126.5 Gy, and 17.1, respectively. The median post-RTOG V(100), V(90), D(90), and CI values were 96.0, 97.8%, 169.2 Gy, and 4.0, respectively. These differences were all statistically significant. CONCLUSIONS: Implementation of the RTOG 98-05 implant planning guidelines has increased coverage of the prostate by the prescription isodose lines compared with our previous technique, as indicated by post-implant dosimetry indices such as V(100), V(90), D(90). The CI was also improved significantly with the protocol guidelines. Our data confirms the validity of the RTOG 98-05 implant guidelines for pre-implant planning as it relates to enlargement of the CTV to ensure adequate margin between the CTV and the prescription isodose lines.

Adult↗
PubMed2003

Treatment of prostate cancer with regional lymph node (N1) metastasis.

Prostate cancer with pathologically documented regional lymph node positive disease has been associated with a dismal prognosis in the past. Clinical and/or biochemical progression is evident within 5 years in over 50% treated with external-beam radiotherapy (EBRT) alone, radical prostatectomy (RP) alone, or androgen deprivation (AD) alone. By 10 years after treatment, greater than 75% progress and over half succumb to prostate cancer. In contrast, the results with the combination of EBRT + AD or RP + AD have been very promising. Ten-year biochemical progression and overall survival rates are roughly 20% and 70%, respectively, for patients with subclinical lymph node involvement. Patients with a 10-year life expectancy should be treated aggressively with long-term AD combined with either EBRT or RP.

Androgen Antagonists↗
PubMed2003

Modifying the American Society for Therapeutic Radiology and Oncology definition of biochemical failure to minimize the influence of backdating in patients with prostate cancer treated with 3-dimensional conformal radiation therapy alone.

PURPOSE: Adoption of the American Society for Therapeutic Radiology and Oncology (ASTRO) consensus definition has been critical for evaluating and comparing outcome following treatment with radiation. However, since its almost universal adoption, several points have remained controversial, notably backdating the date of failure to the point midway between the posttreatment prostate specific antigen (PSA) nadir and the first increase. We evaluated the impact of backdating on no biochemical evidence of disease (bNED) control and suggest changes in the definition. MATERIALS AND METHODS: Between April 1, 1989 and November 30, 1998, 1,017 patients with nonmetastatic prostate cancer were treated with 3-dimensional conformal radiation therapy alone. bNED control was defined using the ASTRO consensus definition. bNED failure was calculated from the time midway between the posttreatment PSA nadir and the first of the 3 consecutive increases in PSA (date of failure A). Four alternate failure time points were chosen, including backdating to the date of the first increase in PSA after the nadir, the date between the first and second consecutive PSA increases, the date between the second and third consecutive PSA increases, and the date of the third increase in PSA after the nadir (dates of failure 1 to 4). Kaplan-Meier estimates were calculated for all definitions of failure as well as hazard functions with time. Subset analyses based on prognostic group and followup time were also performed. RESULTS: The 10-year Kaplan-Meier bNED control rates were 64%, 52%, 47%, 42% and 39% using dates of failure A and 1 to 4, respectively. These differences persisted when patients were stratified by prognostic group. These same differences in bNED control were observed for the long-term followup subset, in which 10-year bNED control rates were 48%, 47%, 44%, 41% and 39% using dates of failure A and 1 to 4, respectively. CONCLUSIONS: Adoption of the ASTRO consensus definition has been crucial for evaluating outcome in the radiation oncology community. However, the date of failure should be moved from the current point to one closer to the point at which failure is declared. Additional analysis with large numbers of patients from multiple institutions is necessary to determine the point.

Adult↗
PubMed2002

Dose response in prostate cancer with 8-12 years' follow-up.

PURPOSE: This communication reports the long-term results of the original group of prostate cancer patients who participated in the first prospective Fox Chase Cancer Center radiation dose escalation study for which 8-12 years of follow-up is now available. METHODS AND MATERIALS: Between March 1, 1989 and October 31, 1992, 232 patients with clinically localized prostate cancer received three-dimensional conformal radiotherapy only at Fox Chase Cancer Center in a prospective dose-escalation study. Of these patients, 229 were assessable. The 8-, 10-, and 12-year actuarial rates of biochemical control (biochemically no evidence of disease [bNED]), freedom from distant metastasis (FDM), and morbidity were calculated. The Cox proportional hazards model was used to assess multivariately the predictors of bNED control and FDM, including pretreatment prostate-specific antigen (PSA) level (continuous), tumor stage (T1/T2a vs. T2b/T3), Gleason score (2-6 vs. 7-10), and radiation dose (continuous). The median total dose for all patients was 74 Gy (range 67-81). The median follow-up for living patients was 110 months (range 89-147). bNED control was defined using the American Society for Therapeutic Radiology and Oncology consensus definition. RESULTS: The actuarial bNED control for all patients included in this series was 55% at 5 years, 48% at 10 years, and 48% at 12 years. Patients with pretreatment PSA levels of 10-20 ng/mL had statistically significant differences (19% vs. 31% vs. 84%, p = 0.0003) in bNED control when stratified by dose (<71.5, 71.5-75.6, and > 75.6 Gy, respectively) on univariate analysis. For the 229 patients with follow-up, 124 (54%) were clinically and biochemically without evidence of disease. Sixty-nine patients were alive at the time of last follow-up, and 55 patients were dead of intercurrent disease. On multivariate analysis, radiation dose was a statistically significant predictor of bNED control for all patients and for unfavorable patients with a pretreatment PSA <10 ng/mL. For the patients with a pretreatment PSA level of 10-20 ng/mL, the radiation dose was a statistically significant predictor across all groups. No radiation dose response was seen for those patients with a pretreatment PSA level >20 ng/mL, although large numbers of patients are required to demonstrate a difference. The radiation dose, Gleason score, and palpation T stage were significant predictors for the entire patient set, as well as for those with pretreatment PSA levels between 10 and 20 ng/mL. The FDM rate for all patients included in this series was 89%, 83%, and 83% at 5, 10, and 12 years, respectively. For patients with pretreatment PSA levels <10 ng/mL, all four covariates (radiation dose, Gleason score, pretreatment PSA, and palpation T stage) were significant predictors of distance metastasis. Using the Radiation Therapy Oncology Group morbidity scale, no difference was noted in the frequency of Grade 2 and 3 genitourinary and Grade 3 gastrointestinal morbidity when patients in this data set were stratified by radiation dose. However, a significant increase occurred in Grade 2 gastrointestinal complications as the radiation dose increased. CONCLUSION: The long-term results of the original Fox Chase radiation dose escalation study with >9 years of median follow-up confirm the existence of a dose response for both bNED control and FDM. The dose response in prostate cancer is real, and the absence of biochemical recurrence after 8 years demonstrates the lack of late failure and suggests cure.

Actuarial Analysis↗
PubMed2002

Biochemical failure rates in prostate cancer patients predicted to have biologically insignificant tumors treated with three-dimensional conformal radiation therapy.

PURPOSE: It has been suggested that patients with prostate cancer meeting the following criteria have pathologically determined potentially biologically insignificant (PBI) tumor and therefore should be considered for observation: clinical stage T1c, PSA density <0.1 ng/mL per gram, absence of Gleason pattern 4 or 5, three or fewer biopsy cores positive for tumor, and tumor involvement of no more than 50% of any core. We compared the biochemical control rates in men meeting the above criteria to those of all low-risk patients (clinical T1c, PSA <or=15, Gleason score 2-6, no perineural invasion) to determine if these criteria reflect a low progression rate after definitive three-dimensional conformal radiation therapy. METHODS AND MATERIALS: Of 352 low-risk patients treated with three-dimensional conformal radiation therapy, 42 met the criteria describing potentially biologically insignificant tumor (PBI group). Median center of prostate dose for all patients was 74 Gy. Biochemical control was defined in accordance with the ASTRO consensus definition. RESULTS: Biochemical control rates at 5 and 7 years were 89% and 89% in the PBI group and 86% and 84% in the remaining low-risk patients, respectively (p = 0.62). CONCLUSIONS: In our experience, men meeting the criteria for potentially biologically insignificant tumor are not selected for a lower risk of biochemical failure and should not be specially selected for observation.

Aged↗
PubMed2002

Advantages of using noncoplanar vs. axial beam arrangements when treating prostate cancer with intensity-modulated radiation therapy and the step-and-shoot delivery method.

PURPOSE: The focus of this work was to compare noncoplanar beam arrangements used for intensity-modulated radiation therapy (IMRT) step-and-shoot delivery to several axial beam arrangements used in the treatment of clinically localized prostate cancer. METHODS AND MATERIALS: A 5-field coronal crossfire beam arrangement was developed for IMRT with the objective of improving upon the rectal and bladder dose-volume histograms obtained using 5-, 7-, and 9-field axial beam arrangements. Additionally, a modified 7-field crossfire technique was developed yielding improved dose distributions. The average values of dose-volume histograms and the time for treatment delivery were evaluated for all plans for 10 randomly chosen patients. RESULTS: Both crossfire IMRT techniques exhibited a 15-25% decrease in dose to the hottest 10% and 20% of the rectum relative to all three axial IMRT techniques. The 5-field crossfire orientation yields slightly higher bladder doses when compared to the other techniques. In selected cases, the 7-field crossfire beam arrangement demonstrates decreased dose to the bladder when compared to all three axial techniques. A mean delivery time of 14 to 17.5 min is noted for the noncoplanar arrangements after positioning and localization. CONCLUSIONS: A technique is described that allows additional normal tissue sparing during dose escalation to the prostate during IMRT delivery. This technique takes advantage of the spatial orientation between the prostate, rectum, and bladder. With patient setup and target localization time aside, a mean treatment time of 14 to 17.5 min allows the delivery of the crossfire plans to conform to standard treatment times.

Humans↗