Biomedical subjects

Michael McLean

Publications and source records attributed to Michael McLean.

18 recordsLinked to original sources

PubMed2006

Computerized tomographic simulation compared with clinical mark-up in palliative radiotherapy: a prospective study.

PURPOSE: To evaluate the impact of computed tomographic (CT) planning in comparison to clinical mark-up (CM) for palliative radiation of chest wall metastases. METHODS AND MATERIALS: In patients treated with CM for chest wall bone metastases (without conventional simulation/fluoroscopy), two consecutive planning CT scans were acquired with and without an external marker to delineate the CM treatment field. The two sets of scans were fused for evaluation of clinical tumor volume (CTV) coverage by the CM technique. Under-coverage was defined as the proportion of CTV not covered by the CM 80% isodose. RESULTS: Twenty-one treatments (ribs 17, sternum 2, and scapula 2) formed the basis of our study. Due to technical reasons, comparable data between CM and CT plans were available for 19 treatments only. CM resulted in a mean CTV under-coverage of 36%. Eleven sites (58%) had an under-coverage of >20%. Mean volume of normal tissues receiving >/=80% of the dose was 5.4% in CM and 9.3% in CT plans (p = 0.017). Based on dose-volume histogram comparisons, CT planning resulted in a change of treatment technique from direct apposition to a tangential pair in 7 of 19 cases. CONCLUSIONS: CT planning demonstrated a 36% under-coverage of CTV with CM of ribs and chest wall metastases.

Bone Neoplasms↗

PubMed2006

Rectal-wall dose dependence on postplan timing after permanent-seed prostate brachytherapy.

PURPOSE: Dose to rectal wall after permanent-seed prostate brachytherapy is dependent on distance between posterior prostatic seeds and anterior rectal wall and is influenced by postimplant periprostatic edema. We analyzed the effect of postplan timing on anterior rectal-wall dose. METHODS AND MATERIALS: Twenty patients received permanent seed 125I brachytherapy as monotherapy (145 Gy). Implants were preplanned by use of transrectal ultrasound (TRUS) and carried out by use of preloaded needles. Postimplant dosimetry was calculated by use of magnetic resonance imaging-computed tomography fusion on Days 1, 8, and 30. The anterior rectal-wall dose is reported as the isodose enclosing 1.0 or 2.0 cc of rectal wall and as the RV100 in cc. RESULTS: The dose to rectal wall increased progressively over time. The median increase in dose to 1.0 cc of rectal wall (RD [1 cc]) from Day 1 to 30 was 39.2 Gy (p < 0.001). RV100 increased from a median of 0.07 cc on Day 1 to 0.67 cc on Day 30. The most significant predictor of rectal-wall dose (RD [1 cc], RD [2 cc], or RV100) was the time of evaluation (p < 0.001). CONCLUSION: Although periprostatic edema cannot be quantified by postimplant imaging, the dose to the anterior rectal wall increases significantly over time as prostatic and periprostatic edema resolve. Critical-organ dose reporting and guidelines for minimizing toxicity must take into account the time of the assessment.

Aged↗

PubMed2005

Sequential evaluation of prostate edema after permanent seed prostate brachytherapy using CT-MRI fusion.

PURPOSE: To analyze the extent and time course of prostate edema and its effect on dosimetry after permanent seed prostate brachytherapy. METHODS AND MATERIALS: Twenty patients scheduled for permanent seed (125)I prostate brachytherapy agreed to a prospective study on postimplant edema. Implants were preplanned using transrectal ultrasonography. Postimplant dosimetry was calculated using computed tomography-magnetic resonance imaging (CT-MRI) fusion on the day of the implant (Day 1) and Days 8 and 30. The prostate was contoured on MRI, and the seeds were located on CT. Factors investigated for an influence on edema were the number of seeds and needles, preimplant prostate volume, transitional zone index (transition zone volume divided by prostate volume), age, and prostate-specific antigen level. Prostate dosimetry was evaluated by the percentage of the prostate volume receiving 100% of the prescribed dose (V(100)) and percentage of prescribed dose received by 90% of the prostate volume (D(90)). RESULTS: Prostate edema was maximal on Day 1, with the median prostate volume 31% greater than preimplant transrectal ultrasound volume (range, 0.93-1.72; p < 0.001) and decreased with time. It was 21% greater than baseline at Day 8 (p = 0.013) and 5% greater on Day 30 (p < 0.001). Three patients still had a prostate volume greater than baseline by Day 30. The extent of edema depended on the transition zone volume (p = 0.016) and the preplan prostate volume (p = 0.003). The median V(100) on Day 1 was 93.6% (range, 86.0-98.2%) and was 96.3% (range, 85.7-99.5%) on Day 30 (p = 0.079). Patients with a Day 1 V(100) >93% were less affected by edema resolution, showing a median increase in V(100) of 0.67% on Day 30 compared with 2.77% for patients with a V(100) <93 % on Day 1. CONCLUSION: Despite the extreme range of postimplant edema, the effect on dosimetry was less than expected. Dose coverage of the prostate was good for all patients during Days 1-30. Our data indicate that postimplant dosimetry on the day of implant is sufficient for patients with good dose coverage (Day 1 V(100) >93%).

Aged↗

PubMed2005

A phase II study of localized prostate cancer treated to 75.6 Gy with 3D conformal radiotherapy.

BACKGROUND AND PURPOSE: To prospectively evaluate toxicity, biochemical failure-free survival (bFFS) and biopsy-proven local control for prostate cancer patients treated with 75.6 Gy in 42 fractions using 6-field conformal radiotherapy to prostate alone. PATIENTS AND METHODS: From 1997 to 1999, 140 patients with T1-2NxM0, Gleason score or=grade 2: 2%, and GU>or=grade 2: 1%. The 3-year bFFS of patients failure-free before biopsy was 93% (95% CI: 83-100) from a negative biopsy and 22% (95% CI: 0-56) from a positive biopsy (P=0.001). Patients reported significantly more late toxicity than physicians (GI: P=0.003, GU: P<0.001). At 5.0 years median follow-up, cause-specific survival was 98% (95% CI: 96-100), overall survival was 91% (95% CI: 86-97), and bFFS was 55% (95% CI: 45-64). CONCLUSIONS: 75.6 Gy caused modest levels of acute and late toxicity. Three-year biopsies predicted subsequent biochemical outcome.

Adenocarcinoma↗

PubMed2004

Polarographic electrode study of tumor oxygenation in clinically localized prostate cancer.

PURPOSE: To describe the oxygenation of clinically localized prostate cancer. METHODS AND MATERIALS: Intraprostatic oxygen tension was measured using the Eppendorf electrode in 55 unanesthetized men with localized prostate cancer before radiotherapy. Measurements were made along two tracks through regions of suspected tumor in the prostate, and core needle biopsies were then obtained from the same regions. RESULTS: The median pO(2) ranged from 0.2 to 57.3 mm Hg, and the grand median pO(2) was 4.5 mm Hg. The percentage of oxygen readings <5 mm Hg (HP(5)) ranged from 0% to 100% (median 60%). The track 1 oxygen readings were greater than those from track 2. Statistically significant heterogeneity was found in the individual oxygen readings: the between- and within-tumor components accounted for 32% and 68% of the total variability, respectively. However, the between-tumor variability in HP(5) significantly exceeded the within-tumor variability (61% vs. 39%). No association was found between oxygen values and clinical factors, including age, T stage, Gleason score, prostate-specific antigen level, hemoglobin concentration, or prior hormonal treatment. No difference was noted in the oxygenation between regions of tumor and normal prostate tissue, as determined from the core biopsies. CONCLUSION: Localized prostate cancer is characterized by marked hypoxia and significant heterogeneity in oxygenation, similar to other human tumors. The normal prostate may contain regions of low oxygen concentration. HP(5), as determined in this study, should adequately discriminate among patients with prostate cancer and allow the independent prognostic significance of oxygenation to be evaluated once the study matures.

Aged↗

PubMed2004

MRI-CT fusion to assess postbrachytherapy prostate volume and the effects of prolonged edema on dosimetry following transperineal interstitial permanent prostate brachytherapy.

PURPOSE: Quality assurance through postplan assessment is an integral part of permanent seed prostate implants. The use of MRI-CT fusion for 1-month postimplant dosimetry permits accurate assessment of prostate volume without seed induced artifact and uncertainties of prostate contour inherent to CT assessments. Routine use of MRI-CT fusion reveals significant prostate edema may persist several weeks. This study evaluates the effect of edema, and its subsequent resolution, on dosimetry. METHODS AND MATERIALS: From May 2001 to June 2003, 241 men were treated with (125)I seed implants based on a transrectal ultrasound (TRUS) preplan. Quality assessment was performed at 1 month by CT-MRI fusion using VariSeed software. Over this 24-month period, 29 patients (12%) with residual edema at 1 month (12-60% >TRUS plan volume), had repeat CT-MRI fusion at 2-4 months to reassess volume and dosimetry. Eleven of the 29 had received prior androgen ablation to shrink the prostate preimplant. RESULTS: For the entire group (n = 241), mean preimplant prostate volume was 33.7 cc and median postplan dosimetric parameters were: V100, 92.2%; D90, 153 Gy; and V150, 53%. For the 29 patients with prolonged edema, mean preimplant volume was 34.8 cc and 1-month volume was 46.1 cc (p <0.001). Mean volume reduction between 1 and 2 months was 13%. The decrease in prostate volume had a significant effect on dosimetry with median increase between 1 month and 2 months in calculated V100 of 9.5%, V150 22.6%, V200 30.1%, and D90 11.5%. CONCLUSIONS: Significant residual edema is seen 1-month postimplant in 12% of prostates and may have a profound effect on dosimetry. Further study is underway to characterize the time course of resolution of the edema, and to perform integral dosimetry based on the changing volume.

Brachytherapy↗

PubMed2004

Factors predicting an increased dose to the penile bulb in permanent seed prostate brachytherapy.

PURPOSE: Erectile dysfunction following permanent seed brachytherapy for prostate cancer may be related to the dose to the penile bulb. We investigated anatomic and dosimetric factors that might contribute to an increased dose to the penile bulb. METHODS AND MATERIALS: One-month CT and MR images were examined for 50 consecutive patients treated with exclusive (125)I permanent seed prostate brachytherapy to a prescribed dose of 145 Gy. Implants were preplanned by transrectal ultrasound (TRUS). Postimplant dosimetry was performed at 1 month using an MRI-CT fusion. Spearman's correlation was used to establish a correlation between dosimetric parameters, anatomical factors, and the dose to the penile bulb. RESULTS: Penile bulb volumes ranged from 1.2-8.5 cc (median, 3.9 cc). The distance from the penile bulb to the prostate apex ranged from 5-33 mm (median, 15.5 mm). D50 of the penile bulb ranged from 13-121 Gy. The range for the V45 (65 Gy) was 0-87%; only 3% of patients had >2 cc covered by this isodose and in 16% of patients the V45 covered more than 50% of the penile bulb. About one-third of the patients received a dose to the bulb that would put them at a high risk of erectile dysfunction after external beam radiation, if the dose were radiobiologically equivalent. There was a significant inverse correlation between the distance between the prostate apex and the penile bulb, and the dosimetric parameters of the bulb: r = -0.548, -0.656, p = < 0.01. The further caudal the apex was from the symphysis, the closer it was to the penile bulb (r = -0.564, p = <0.01). We could not find a correlation between the dose to the prostate or its apex and the dose to the penile bulb. CONCLUSION: When the prostate apex is close to the penile bulb, care should be taken to limit the dose to the penile bulb, if possible. This may reduce the incidence of erectile dysfunction and urinary toxicity after permanent seed prostate brachytherapy.

Brachytherapy↗

PubMed2004

A randomized trial of supine vs. prone positioning in patients undergoing escalated dose conformal radiotherapy for prostate cancer.

BACKGROUND AND PURPOSE: The optimal treatment position for patients receiving radical radiation therapy for prostate cancer has been a source of controversy. To resolve this issue, we conducted a randomized trial to evaluate the effects of supine and prone positioning on organ motion, positioning errors, and dose to critical organs during escalated dose conformal irradiation for localized prostate cancer and patient and therapist satisfaction with setup technique. PATIENTS AND METHODS: Twenty eight patients were randomized to commence treatment immobilized in the supine or prone position and were subsequently changed to the alternate positioning for the latter half of their treatment. Patients underwent CT simulation and conformal radiotherapy planning and treatment in both positions. The clinical target volume encompassed the prostate gland. Alternate day lateral port films were compared to corresponding simulator radiographs to measure the isocentre positioning errors (IPE). Prostate motion (PM) and total positioning error (TPE) were measured from the same films by the displacements of three implanted fiducial markers. Dose volume histograms (DVHs) for the two treatment positions were compared at the 95, 80 and 50% dose (D%) levels. The patients and radiation therapists completed weekly questionnaires regarding patient comfort and ease of setup. RESULTS: Seven patients, who started in the supine position, subsequently refused prone position and received their whole treatment supine. Small bowel in the treatment volume, not present in the supine position, prevented one patient from being treated prone. PM in anterior posterior direction was statistically significantly less in the supine position (P<0.05). There was no significant difference in superior inferior PM for the two treatment positions. No statistically significant difference between supine and prone positioning was observed in isocentre positioning error (IPE) or total positioning error (TPE) due to a policy of daily pre-treatment correction. However, more pre-treatment corrections were required for patients in the prone position. The DVH analysis demonstrated larger volumes of the bladder wall, rectal wall and small bowel within the D95, D80 and D50% when comparing the planning target volumes (PTVs) actually treated for prone positioning. When the prone PTV was expanded to account for the greater PM encountered in that position, a statistically significant difference (P<0.007) was observed in favour of the supine position at all dose levels. In the prone position, four patients had small bowel within the 60 Gray (Gy) isodose and in the supine position, no patients had small bowel in the 60 or 38Gy volumes. Supine position was significantly more comfortable for the patients and setup was significantly easier for the radiation therapists. The median patient comfort score was 0.79 (Standard deviation (SD) 0.03) supine and 0.45 (SD 0.05) prone (P<0.001) The therapist convenience of setup was 0.80 (SD 0.016) supine and 0.54 (SD 0.025) prone (P<0.005). No statistically significant difference was seen for the other parameters studied. CONCLUSIONS: We demonstrated significantly less PM in the supine treatment position. There was no difference for either treatment position in IPE or TPE, however, more pre-treatment corrections were required in the prone position. Prone position required a larger PTV with resulting increased dose to critical organs. There were statistically significant improvements at all dose levels for small bowel, rectal wall and bladder wall doses in the supine position once corrections were made for differences in organ motion. Linear analogue scores of patient comfort and radiation therapist convenience demonstrated statistically significant improvement in favour of the supine position. Supine positioning has been adopted as the standard for conformal prostatic irradiation at our centre.

Aged↗

PubMed2004

A BALB/c murine lung alveolar carcinoma used to establish a surgical spontaneous metastasis model.

Line-1, a weakly immunogenic lung tumor cell line derived from the BALB/c mouse, metastasizes spontaneously to the lungs of mice following subcutaneous administration. The parameters that influence metastasis as well as the progression of metastatic lung disease following surgical resection of primary subcutaneous tumors were characterized. Histological analysis of the lungs obtained from mice bearing different size subcutaneous tumors demonstrated that >90% of the mice developed micrometastatic disease in the lungs when the tumor exceeded 650 mm3 in size. Surgical resection of subcutaneous tumors resulted in the cure of primary disease in 95% of the mice. Macroscopic tumor nodules were grossly visible in the lungs of 75% of the mice 5 weeks after surgery. Serum amyloid A level correlated with primary tumor burden and was diagnostic for the presence of metastatic disease. The efficiency of metastasis, post-surgical primary tumor recurrence and long-term survival were significantly different between BALB/c mice obtained from different suppliers. The Line-1-BALB/c surgical metastasis model provides a clinically relevant tool for the evaluation of anti-cancer therapies, especially those that are designed to target long-term suppression of minimal residual disease following surgical intervention.

Animals↗

PubMed2003

The success of data collection in the palliative setting--telephone or clinic follow-up?

Assessment of outcomes is essential in order to improve available palliative treatments. Collecting follow-up information can be a challenging task in the palliative setting. We compared the effectiveness of data collection by telephone contact and clinic visit in 112 patients with brain metastases treated with whole-brain radiotherapy. The first 56 patients (group A) were followed by telephone only. The second 56 patients (group B) were asked to attend an outpatient clinic appointment 4 weeks after radiotherapy. Successful contact was defined as obtaining data at week 4. Patients in the two groups did not differ significantly with regard to age, sex, performance status, primary site, number of brain metastases, or the treatment given. The proportions of patients with successful follow-up contact at week 4 were 45% and 61% in groups A and B, respectively ( P = 0.09). The quality of the collected data did not differ significantly between the two groups. The side effects and responses to therapy were similar. However, there were significantly more patients with a reduced dose of dexamethasone among the successful contacts in group B, which probably reflected the better condition of the patients coming back to clinic at week 4. In conclusion, there was a trend towards more successful data collection in our clinic follow-up. Some of the observed outcome data suggest that the two methods of follow-up might be reaching different populations of patients; considering this and the high attrition rate, a combined follow-up strategy of clinic and telephone contacts might be the best strategy.

Ambulatory Care↗

PubMed2002

Palliative radiation for vertebral metastases: the effect of variation in prescription parameters on the dose received at depth.

PURPOSE: To assess the effect of prescription parameters on the dose received by the spine during palliative radiotherapy. MATERIALS AND METHODS: In a survey, members of the Canadian Association of Radiation Oncologists were asked to define their prescription parameters for vertebral metastases. The depth of the spinal canal and vertebral body at 8 spinal levels was measured in 20 magnetic resonance imaging studies (MRIs). Survey results were applied to the measurements to assess the dose received at depth. The depth of spinal structures assessed at simulation and by diagnostic imaging was compared. RESULTS: Prescriptions were most commonly to D(max) 3 cm or 5 cm using 60Co-6MV photons delivering 8-30 Gy in 1-10 fractions. Mean depths from MRI were: posterior spinal canal, 5.5 cm; anterior spinal canal, 6.9 cm; and anterior vertebral body, 9.6 cm. Application of the prescription parameters from the survey to these measurements showed a wide range in the dose at depth with variation in technique. Depths measured at simulation correlated well with diagnostic imaging. CONCLUSION: The spinal canal and vertebral body lie >5 cm beneath the skin, and the dose received varies by up to 50% with changes in prescription depth. We suggest a suitable prescription point for vertebral metastases and a method for determining this at simulation.

Adult↗

PubMed2002

Factors influencing risk of acute urinary retention after TRUS-guided permanent prostate seed implantation.

PURPOSE: To look for factors predictive of acute urinary retention (AUR) after permanent seed prostate brachytherapy. METHODS AND MATERIALS: From March 1999 to February 2001, 150 permanent seed prostate implants were performed at Princess Margaret Hospital (Stage T1c, n = 113; T2a, n = 37; mean prostate-specific antigen level 5.9 ng/mL, prescription dose 145 Gy per Task Group No. 43). alpha-Blockers were used routinely after implantation. Dosimetry was based on the 1-month postimplant CT scan. The International Prostate Symptom Score (IPSS) and catheterization were recorded at 1 month and 3 months and then every 3 months. The following variables were examined: age, baseline IPSS, prior androgen ablation, prostate transrectal ultrasound volume, number of seeds, D(90), V(100), V(200), and urethral dose. RESULTS: Twenty patients (13%) experienced AUR. No difference was seen in the mean D(90) (149 Gy vs. 152 Gy, p = 0.6), V(100) (90% vs. 91%, p = 0.6), V(200) (23% vs. 25% p = 0.4), IPSS (6.4 vs. 5.9, p = 0.8), or maximal urethral dose (204 Gy vs. 210 Gy, p = 0.5). The prostate volume was significantly larger in men with AUR (39.8 cm(3) vs. 34.3 cm(3), p = 0.003), and the mean number of seeds was higher (112 vs. 103, p = 0.006). Of the 20 patients experiencing AUR, 11 (55%) had received prior antiandrogen therapy to downsize their prostates vs. 35 (27%) of the 130 who did not have AUR (p = 0.02). Multivariate analysis showed prostate volume and prior hormone use to be independent predictors of AUR. CONCLUSIONS: Implant quality as determined by D(90), V(100), V(200), and urethral dose did not predict AUR. Prostate size was the major determinant of AUR. For any given prostate size, prior androgen ablation increased the risk of AUR. Men with larger prostates should be aware of the increased risk when contemplating brachytherapy.

Aged↗

PubMed2002

Topiramate Overdose: Clinical and Laboratory Features.

Limited data exist on overdose with new antiepileptic drugs. We reviewed the medical records of two patients who took a topiramate overdose as a suicide attempt. We recorded their medical and seizure histories, concomitant antiepileptic medications, neurologic examination, and laboratory findings at the time of presentation following the overdose. We also recorded their progress and the evolution of laboratory abnormalities. Both patients progressed to coma and had generalized convulsive status epilepticus, requiring intubation and treatment with benzodiazepines. Both patients recovered within 2 days but had a non-anion-gap metabolic acidosis that persisted for 5-6 days. Physicians should carefully monitor patients treated with topiramate who develop signs of clinical depression. The non-anion-gap metabolic acidosis observed may be due to inhibition of renal cortical carbonic anhydrase.

Journal Article↗

PubMed2002

Interobserver variation in postimplant computed tomography contouring affects quality assessment of prostate brachytherapy.

PURPOSE: Permanent seed implants are accepted treatment of early stage prostate cancer. Implant quality is assessed by post implant CT-based dosimetry but prostate contours on CT images are obscured by metallic seed artefact and edema. Outcome depends on implant quality, but perceived implant quality depends on accurate prostate contouring. This study documents inter observer variation in prostate contouring on post implant CT scans. METHODS AND MATERIALS: Ten patients had implant dosimetry calculated on 4 copies of the post implant CT scan. Prostate contours from MRI-CT fusion were the gold standard for prostate edge identification. CTs were contoured by an experienced prostate brachytherapist matching CT images to the pre implant TRUS, and by 2 GU radiation oncologists experienced in conformal radiotherapy planning. Dosimetry was compared to that obtained using MRI-CT fusion in terms of D90 and V100. RESULTS: Contours and dosimetry were not reproducible among the 3 observers. The V100's of the experienced brachytherapist differed from that of MRI-CT fusion by a mean of 2.4% compared to 9.1% and 4.4% for observers 1 and 2, and the D90 by a mean of 9.3 Gy compared to 30.3 and 14.4 Gy for observers 1 and 2. CONCLUSIONS: Quality assessment of prostate brachytherapy based on 1 month post implant CT is difficult. This may obscure the dose-response relationship in brachytherapy as well as create problems for quality assurance in multicentre trials evaluating brachytherapy against standard modalities. Whenever possible, MRI-CT fusion should be employed to verify prostate contours post implant.

Brachytherapy↗

PubMed2002

The utility of transition zone index in predicting acute urinary morbidity after 125I prostate brachytherapy.

PURPOSE: Acute urinary morbidity after prostate brachytherapy is common and, although usually self-limited, can be distressing to the patient, especially if acute urinary retention (AUR) develops. We undertook to determine whether prospective measurement of the transition zone index would be predictive of either urinary retention or the severity of urinary symptoms after brachytherapy. METHODS AND MATERIALS: One hundred men undergoing transperineal interstitial permanent prostate brachytherapy (TIPPB) with 125I underwent transrectal ultrasound before the procedure to measure prostate and transition zone (TZ) volumes. TZ index was calculated as TZ volume divided by total prostate volume. TIPPB was performed between July 2000 and January 2002. Patients were observed for 1, 3, or 6 months with an International Prostate Symptom Score (IPSS) at each visit. alpha-Blockers were prescribed prophylactically in all patients. Postimplant dosimetry was performed at 1 month by using CT/MRI fusion for all patients. RESULTS: The mean patient age was 65.1 years (range, 46-77 years). There were 59 T1c tumors and 41 T2a tumors. The Gleason score was 6 in 86% of patients, with 3% being Gleason 4 or 5 and 11% Gleason 7. The mean baseline IPSS was 7.4, with the mean at 1 month being 17.3; at 3 months, 14.4; and at 6 months, 11.3. Baseline IPSS was the only factor predictive of IPSS at 1 and 3 months after TIPPB. Neoadjuvant androgen deprivation was used for 26% of men for 2-6 months to reduce prostate size before the procedure. AUR developed in 17%. In univariate analysis, prior hormone therapy (p = 0.002), duration of hormone therapy (p = 0.005), TZ index (p = 0.014), number of seeds implanted (p = 0.016), T stage (p = 0.035), percentage of the prostate volume receiving at least the full prescribed dose (V100, p = 0.036), percentage of the prostate volume receiving > 200% of the prescribed dose (V200, p = 0.037), and prostate volume (p = 0.038) were all predictive of AUR. When the TZ index was divided into quartiles, the risk of AUR was 4%, 16%, 20%, and 28% (p = 0.032). However, in multivariate analysis, TZ index was no longer predictive of AUR. CONCLUSIONS: Baseline urinary function is the only factor predictive of symptom scores at 1 and 3 months after brachytherapy. TZ index, initial prostate volume, and use of neoadjuvant hormones are interrelated and are all predictive of AUR in univariate analysis, but in multivariate analysis, TZ index is not an independent prognostic factor.

Acute Disease↗

PubMed2002

Clinical and biochemical outcome of conventional dose radiotherapy for localized prostate cancer.

PURPOSE: To retrospectively review the results of conventional dose radical radiotherapy for clinical stage T1 and T2 prostate cancer, and to identify the factors that predict the biochemical relapse-free rate. METHODS: The records were reviewed of 706 hormonally-naïve men with clinical stage T1T2 prostate cancer treated with radical radiotherapy (RT) between 1987-1994 at the Princess Margaret Hospital. The median prostate RT dose was 65 Gy in 35 fraction (range 52 Gy in 20 fractions to 67 Gy in 37 fractions). Pelvic lymph nodes were included in the treatment volume and treated to a median dose of 45 Gy in 25 fractions for 283 cases (40%). The primary end-point was biochemical relapse-free survival from RT using the American Society of Therapeutic Radiology and Oncology (ASTRO) consensus criteria. Favourable, intermediate and unfavourable pre- treatment prognostic groupings were derived from the initial PSA, T-category, and Gleason score using Cox regression analysis. Secondary end-points included survival, metastases-free survival and clinical local control. RESULTS: The overall biochemical relapse-free rate at 2 and 5 years was 63% and 45% respectively. Overall survival at 5 years was 87%, and metastases-free survival was 86%. Local control by DRE was 72% at 5 years. Multivariate analysis of variables associated with time to biochemical failure after RT showed that pre-RT PSA, T-category and Gleason score were significant independent predictors with hazard ratios of 1.33 (P = 0.0001), 1.22 (P = 0.01) and 1.33 (P = 0.029) respectively. PSA nadir was an early indicator of biochemical failure. The biochemical failure rate at 3 years was 20% for a PSA nadir < or = 0.5 ng/ml and 85% for a PSA nadir > or = 2.0 ng/ml (P < 0.0001). CONCLUSION: The results of conventional dose RT were unsatisfactory for all risk categories, and overall, less than half of the treated patients remained in biochemical remission at 5 years. These men require more aggressive therapy, that may include dose escalation with conformal techniques, and neoadjuvant/adjuvant androgen deprivation therapy. These results highlight the need to support new and on-going clinical trials for management of localized disease.

Aged↗

PubMed1998

Progression of prostate cancer despite undetectable serum prostate specific antigen.

The serum prostate specific antigen (PSA), having been a valid marker for prostate cancer in 2 patients at the time of their diagnosis, ultimately became undetectable (<0.1 ng/ml) despite evidence of disease progression. This was documented by isotope bone scans and the results of subsequent CT guided bone biopsies. In both biopsy specimens, immunohistochemical staining for PSA was negative, but positive for prostate acid phosphatase after microwave antigen enhancement. In both cases the serum prostate acid phosphatase (PAP) had remained within normal limits. We would caution that prostate cancer may recur and progress with an undetectable serum PSA after antiandrogen therapy.

Journal Article↗

PubMedDate not supplied

Relationship of the International Prostate Symptom score with urinary flow studies, and catheterization rates following 125I prostate brachytherapy.

PURPOSE: Prostate cancer patients undergoing 125I brachytherapy were reviewed. A relationship between pretreatment risk factors including International Prostate Symptom (IPS) score, urinary flow studies, and posttreatment urinary morbidity was assessed. METHODS AND MATERIALS: Pretreatment IPS scores and urinary flow studies on 207 patients were reviewed. Relationship between scores and acute urinary morbidity was evaluated. RESULTS: Median age, 64 years; median baseline IPS score, 9; median prostate volume, 36 cc. Catheterization was required in 18% of patients. Baseline IPS score and peak flow rate (PFR) varied inversely, demonstrating that PFR for patients requiring a catheter was lower than that for those not requiring catheterization. Univariate regression showed that prostate volume, prior hormone therapy, and PFR were statistically predictive of postimplant urinary retention. For every one-unit increase in PFR, the odds of catheterization decreased by 6%. Multivariate analysis demonstrated that only PFR and prostate volume were predictive of postimplant urinary retention. CONCLUSIONS: Pretreatment IPS questionnaire and urinary flow studies assist in predicting risk of urinary morbidity and retention post-125I brachytherapy for prostate cancer.

Aged↗