Pradip Amin

bcl-2/bax RATIO AS A PREDICTIVE MARKER FOR THERAPEUTIC RESPONSE TO RADIOTHERAPY IN PATIENTS WITH PROSTATE CANCER

OBJECTIVES Markers predictive of therapeutic response of prostatic tumors to radiotherapy may have major significance in optimizing effective treatment of prostate cancer. Because inherent cellular radioresistance plays a critical role in the failure of radiotherapy, in this study, we investigated whether there is a correlation between the ratio of two apoptosis regulators, bcl-2 (apoptosis suppressor) and bax (apoptosis inducer) in prostatic tumors and the clinical response to radiotherapy in patients with localized prostate cancer. METHODS A retrospective review of records of 41 patients who underwent external beam radiotherapy for prostate cancer was conducted. On the basis of post-treatment prostate biopsy and prostate-specific antigen (PSA) criteria, the cancers of 20 patients were classified as radiation nonresponders and 21 as radiation responders. Immunohistochemical analysis was performed on paraffin-embedded prostate sections to determine the level of expression of the two apoptotic proteins, bcl-2 and bax, in tumor cells. RESULTS bcl-2 immunoreactivity was significantly higher in prostatic tumors not responsive to radiotherapy (38.6+/-4.1), compared with the radiation responders (24.1+/-4.6) (P <0.001). Expression of bax protein was lower in nonresponders, but values were not significantly different from the responders. The resulting significantly higher bcl-2/bax ratio (P <0.01) correlated with poor therapeutic responsiveness of prostate cancer to radiotherapy (1.12+/-0.12 and 0.56+/-0.13, for nonresponders and responders, respectively). This correlation (r=0.67) was independent of age, PSA, and Gleason score. CONCLUSIONS These findings suggest that patients with an elevated bcl-2/bax ratio are at increased risk of their cancer failing to respond to radiotherapy. This study suggests a predictive value for the bcl-2/bax ratio as a potential molecular marker for predicting radioresistance of prostatic tumors.

Gamma knife stereotactic radiosurgery for patients with glioblastoma multiforme

OBJECTIVE Stereotactic radiosurgery (SRS) has become an effective therapeutic modality for the treatment of patients with glioblastoma multiforme (GBM). This retrospective review evaluates the impact of SRS delivered on a gamma knife (GK) unit as an adjuvant therapy in the management of patients with GBM. METHODS Between August 1993 and December 1998, 82 patients with pathologically confirmed GBM received external beam radiotherapy (EBRT) at the University of Maryland Medical Center. Of these 82 patients, 64 with a minimum follow-up duration of at least 1 month are the focus of this analysis. Of the 64 assessable patients, 33 patients were treated with EBRT alone (Group 1), and 31 patients received both EBRT plus a GK-SRS boost (Group 2). GK-SRS was administered to most patients within 6 weeks of the completion of EBRT. The median EBRT dose was 59.7 Gy (range, 28–70.2 Gy), and the median GK-SRS dose to the prescription volume was 17.1 Gy (range, 10–28 Gy). The median age of the study population was 50.4 years, and the median pretreatment Karnofsky performance status was 80. Patient-, tumor-, and treatment-related variables were analyzed by Cox regression analysis, and survival curves were generated by the Kaplan-Meier product limit. RESULTS Median overall survival for the entire cohort was 16 months, and the actuarial survival rate at 1, 2, and 3 years were 67, 40, and 26%, respectively. When comparing age, Karnofsky performance status, extent of resection, and tumor volume, no statistical differences where discovered between Group 1 versus Group 2. When comparing the overall survival of Group 1 versus Group 2, the median survival was 13 months versus 25 months, respectively (P = 0.034). Age, Karnofsky performance status, and the addition of GK-SRS were all found to be significant predictors of overall survival via Cox regression analysis. No acute Grade 3 or Grade 4 toxicity was encountered. CONCLUSION The addition of a GK-SRS boost in conjunction with surgery and EBRT significantly improved the overall survival time in this retrospective series of patients with GBM. A prospective, randomized validation of the benefit of SRS awaits the results of the recently completed Radiation Therapy Oncology Group’s trial RTOG 93-05.

Comparison of three treatment options for single brain metastasis from lung cancer

Whole brain radiotherapy (WBRT), stereotactic radiosurgery (SRS), and the combination of both treatment methods were used for the management of single brain metastasis from lung cancer. The purpose of this study is to compare these three different treatment options in terms of local response, survival, and quality of life. From June 1995 to July 1998, 70 lung cancer patients with new diagnosed single brain metastasis were treated with either WBRT alone (n = 29), or SRS alone (n = 23), or the combination of both methods (n = 18). Multiple endpoints, including survival, freedom from local progression (FFLP), freedom from new brain metastasis (FFNBM), local control, Karnofsky performance status (KPS), and causes of death, were measured from the date of treatment completion and compared using univariate and multivariate analyses. For patients treated with WBRT‐alone, SRS‐alone, and SRS+WBRT, the median survivals were 5.7, 9.3, and 10.6 months, the median FFLP were 4.0, 6.9, and 8.6 months, the median FFNBM were 4.1, 6.7, and 8.6 months, and the local response rates were 55.6, 87.0, and 88.9%, respectively. Four of the 29 patients treated with WBRT‐alone continued with progression of disease. The post treatment KPS showed improvement in 41.4, 82.6, and 88.9% of patients treated with WBRT‐alone, SRS‐alone, and SRS+WBRT, respectively. The progression of new and/or recurred metastatic brain tumor as the cause of death accounted for 51.7%, 50.0%, and 28.3% of the patients treated with WBRT‐alone, SRS‐alone, and SRS+WBRT, respectively. Univariate analyses showed that the significant differences among the three treatment arms were observed based on all of the above mentioned endpoints. However, the comparison between SRS‐alone and SRS+WBRT groups indicated that adding WBRT only improves FFNBM (P = 0.0392). Cox regression analyses revealed no significant difference in both of the KPS (P = 0.1082) and causes of death (P = 0.081) among the three arms. Both SRS alone and SRS+WBRT seem better in prolonging life and improving quality of life than WBRT alone for patients with single brain metastasis from lung cancer. But the combined therapy did not show significant advantage over SRS alone in improving survival, enhancing local control, and quality of life except for a more favorable FFNBM. Further investigation via a randomized trial is needed to access the value of adding WBRT to SRS in the management of this group of patients. Int. J. Cancer (Radiat. Oncol. Invest.) 90, 37–45 (2000).

GliaSite brachytherapy for treatment of recurrent malignant gliomas: A retrospective multi-institutional analysis

OBJECTIVE:To review the cumulative experience of 10 institutions in treating recurrent malignant gliomas with the brachytherapy device, GliaSite Radiation Therapy System. METHODS:The patient population consisted of 95 patients with recurrent grade 3 or 4 gliomas, a median age of 51 years, and a median Karnofsky performance status score of 80. All patients had previously undergone resection and had received external beam radiotherapy as part of their initial treatment. After recurrence, each patient underwent maximal surgical debulking of their recurrent lesion and placement of an expandable balloon catheter (GliaSite) in the tumor cavity. The balloon was afterloaded with liquid 125I (Iotrex) to deliver a median dose of 60 Gy to an average depth of 1 cm with a median dose rate of 52.3 Gy/hr. Patients were carefully followed with serial magnetic resonance imaging and monthly examinations for tumor progression, side effects, and survival. RESULTS:The median survival for all patients, measured from date of GliaSite placement, was 36.3 weeks with an estimated 1 year survival of 31.1%. The median survival was 35.9 weeks for patients with an initial diagnosis of glioblastoma multiforme and 43.6 weeks for those with non- glioblastoma multiforme malignant gliomas. Analysis of the influence of various individual prognostic factors on patient survival demonstrated that only Karnofsky performance status significantly predicted for improved survival. There were three cases of pathologically documented radiation necrosis. CONCLUSION:Reirradiation of malignant gliomas with the GliaSite Radiation Therapy System after reresection seems to provide a modest survival benefit above what would be expected from surgery alone. This report not only confirms the initial results of the feasibility study but provides evidence that similar outcomes can be obtained outside of a clinical trial.

Preservation of visual fields after peri‐sellar gamma‐knife radiosurgery

Radiosurgical treatment of pituitary and peri‐sellar tumors has become an increasingly utilized modality as an alternative to conventional radiotherapy and surgery. Such radiosurgery results in a relatively high dose of radiation to the optic chiasm. The clinical data establishing safe single‐fraction doses to the chiasm is immature, although taken together previous literature suggests a recommended maximal dose of 8 Gy. Optic neuropathy, when it occurs, tends to take place within 2 years of treatment. We evaluated the visual fields of 20 sequential patients that received significant doses to the optic chiasm by Gamma‐knife radiosurgery. There were 17 cases of pituitary adenoma and 3 cases of meningioma, and two patients refused follow‐up testing. Preoperative visual field and cranial nerve examinations were done prior to radiosurgery and in follow‐up, with a median follow‐up of 24 months. There were no cases of quantitative visual field deficit induced by treatment. No patients developed symptomatic visual deterioration. Radiat. Oncol. Invest. 90:343–350, 2000. 2000 Wiley‐Liss, Inc.

Optimized intensity-modulated arc therapy for prostate cancer treatment†

We recently implemented intensity‐modulated arc therapy (IMAT) at our institution. In this study, we evaluate the dosimetric merits of the application of this technique to the treatment of prostate cancer. Each IMAT treatment plan incorporated bilateral overlapping arcs. The dose from each beam segment was computed using the three‐dimensional dose model of a clinical treatment planning system (Render Plan 3.5, Precision Therapy). The weights assigned to the individual arc segments were optimized using a gradient search method. For 12 patients, comparisons were made between the IMAT treatment plans and corresponding plans using fixed cone‐beam intensity‐modulated radiotherapy (IMRT) from a commercial inverse planning system (CORVUS, NOMOS Corp.). We found that the optimized IMAT treatments produced similar dose distributions to the IMRT deliveries. Compared with the IMRT treatments, the IMAT treatments produced slightly less target dose homogeneity with consistently greater sparing of the rectum in regions of lower dose. The trade‐off between target dose conformity and rectum sparing can be adjusted in both optimization procedures. Because the total beam‐on time for IMAT delivery is 1 to 2 minutes with approximately 5–6 minutes of patient setup time, the delivery efficiency of the IMAT treatment was significantly better than the multiple‐beam IMRT treatment.

Acute complications following gamma knife radiosurgery are rare

BACKGROUND Gamma knife radiosurgery (GKR) is a safe and effective alternative to surgery for intracranial lesions. Most studies evaluating toxicity after GKR have concentrated on the delayed radiation effects. METHODS We retrospectively reviewed 835 consecutive GKR cases for early (within 7 days) neurological complications or death. RESULTS We identified a total of 18 patients (2.2%) who had a neurological event or death. Five (0.6%) patients developed new focal deficits, 12 (1.4%) patients experienced a seizure and there were three (0.4%) deaths. Two deaths were related to development of seizures and neurological deterioration. One death was caused by a respiratory arrest related to the patients primary cancer. Of the five patients with neurological deficits, none had a persistent deficit. In two cases the neurological deficits were due to an increase in edema. Whether this occurred as a result of the gamma knife treatment or was the natural progression of the tumor is unclear. CONCLUSIONS Complications after GKR are uncommon and the risk of a permanent deficit arising from an acute neurological event is exceedingly low.

Gamma knife radiosurgery for the treatment of brain metastases.

One hundred and ninety-three patients with brain metastases from various primary sites received Gamma Knife radiosurgery (GKR) from July 1992 to August 1997 and were reviewed to evaluate their clinical outcome. Survival follow-up was available on 173 patients. Whole-brain radiation therapy was also administered to 148 of these patients. The median survival was 13.1 months from initial detection of brain metastases, and 7.5 months from GKR. Univariate and multivariate analyses were performed to determine prognostic factors that influenced survival following GKR. Enhanced survival is observed in patients with radiosensitive tumor types, supratentorial tumor, history of brain tumor resection, controlled primary site, and absent extracranial metastases. Local lesion control was obtained in 82% of the patients according to their last follow-up MRI scan. GKR is an effective means of treating patients with brain metastases.

Apoptosis and bcl-2 expression in prostate cancer: significance in clinical outcome after brachytherapy.

PURPOSE Radiation induced apoptosis of prostate cancer cells may have therapeutic and prognostic significance in patients treated with radiotherapy. We determined whether the ability of prostate tumor cells to undergo apoptosis has potential value for predicting the clinical response of patients with prostate cancer to brachytherapy. MATERIALS AND METHODS A total of 76 patients with clinical stages T1 to 2 disease who were not receiving adjuvant therapy underwent transperineal implantation with 125iodine or 103palladium seeds and biopsy 7 to 23 months (median 12) after therapy. Nonresponders were classified using the American Society for Therapeutic Radiology and Oncology criteria. The apoptotic index was analyzed using the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling assay in archived biopsy specimens from 76 treated and 19 matched pretreatment control patients. Serial sections of prostatic tumors were also evaluated for the expression of bax and bcl-2 proteins (apoptosis regulators) by immunohistochemical testing. RESULTS A significant increase in the apoptotic index was detected in post-brachytherapy compared with pretreatment prostate specimens (3.1% versus 2%, p <0.05), as well as in patients with negative biopsy at followup compared with those with persistent malignancy (3.4% versus 1.8%, p = 0.02). In addition, there was a significant elevation in bcl-2 expression in prostatic tissue in patients with treatment failure compared with responders (30.5% versus 13.1%, p <0.05). CONCLUSIONS To our knowledge this is the first study to establish a correlation of apoptosis induction and bcl-2 over expression with treatment outcome in patients with prostate cancer after brachytherapy. Our findings have significant clinical implications for identifying the value of the apoptotic index and bcl-2 expression in prostatic tumors for predicting the therapeutic response to brachytherapy.

Risk group stratification in patients undergoing permanent 125I prostate brachytherapy as monotherapy

PURPOSE Patients undergoing prostate brachytherapy (PB) as monotherapy are often selected on the basis of favorable pretreatment factors. However, intermediate and high-risk prostate cancer patients are commonly offered PB as monotherapy without the addition of external beam radiotherapy (EBRT) or hormonal therapy. This series reports the outcome of patients undergoing PB as monotherapy who were stratified into low, intermediate, and high-risk groups with extended follow-up. METHODS AND MATERIALS A total of 102 patients with clinically localized prostate cancer underwent PB alone as monotherapy. EBRT or hormonal therapy was not part of their initial treatment. Prostate-specific antigen (PSA) relapse-free survival (PRFS) was determined in accordance with the American Society for Therapeutic Radiology and Oncology consensus statement. Patients were stratified as at favorable risk (Stage T1-2a, pretreatment PSA < or =10.0 ng/mL, and Gleason score < or =6), intermediate risk (one prognostic indicator with a higher value), or unfavorable risk (> or =2 indicators with higher values). The median follow-up period for patients in this series was 7 years (range 2.1-9.7). The median age at treatment was 71 years (range 54-80), and the median prescribed dose of (125)I was 145 Gy. RESULTS Forty patients experienced a biochemical relapse at a median of 1.9 years (range 0.4-4.2). The 5-year actuarial PRFS rate for patients with favorable, intermediate, and unfavorable risk was 85%, 63%, and 24%, respectively (p <0.0001). All but 1 patient had the relapse within the first 5 years of treatment. When stratifying patients on the basis of their pretreatment PSA level, the 5-year PRFS rate for men with a PSA < or =10 ng/mL vs. >10 ng/mL was 78% vs. 35%, respectively (p = 0.0005). Furthermore, the 5-year PRFS rate for men with a Gleason score of < or =6 vs. > or =7 was 74% vs. 33%, respectively (p = 0.0001). No difference was found between Stage T1-T2a and Stage T2b or higher (64% vs. 54%, respectively; p = 0.353). CONCLUSION On the basis of risk stratification, PB as monotherapy produces comparable PRFS to EBRT and surgery at 7 years of follow-up. PB as monotherapy is particularly ineffective in patients with unfavorable risk factors, and additional therapy is warranted.