Biomedical subjects

Charles Catton

Publications and source records attributed to Charles Catton.

25 records · Page 2Linked to original sources

PubMed2002

Preoperative versus postoperative radiotherapy in soft-tissue sarcoma of the limbs: a randomised trial.

BACKGROUND: External-beam radiotherapy (delivered either preoperatively or postoperatively) is frequently used in local management of sarcomas in the soft tissue of limbs, but the two approaches differ substantially in their potential toxic effects. We aimed to determine whether the timing of external-beam radiotherapy affected the number of wound healing complications in soft-tissue sarcoma in the limbs of adults. METHODS: After stratification by tumour size (< or = 10 cm or >10 cm), we randomly allocated 94 patients to preoperative radiotherapy (50 Gy in 25 fractions) and 96 to postoperative radiotherapy (66 Gy in 33 fractions). The primary endpoint was rate of wound complications within 120 days of surgery. Analyses were per protocol for primary outcomes and by intention to treat for secondary outcomes. FINDINGS: Median follow-up was 3.3 years (range 0.27-5.6). Four patients, all in the preoperative group, did not undergo protocol surgery and were not evaluable for the primary outcome. Of those patients who were eligible and evaluable, wound complications were recorded in 31 (35%) of 88 in the preoperative group and 16 (17%) of 94 in the postoperative group (difference 18% [95% CI 5-30], p=0.01). Tumour size and anatomical site were also significant risk factors in multivariate analysis. Overall survival was slightly better in patients who had preoperative radiotherapy than in those who had postoperative treatment (p=0.0481). INTERPRETATION: Because preoperative radiotherapy is associated with a greater risk of wound complications than postoperative radiotherapy, the choice of regimen for patients with soft-tissue sarcoma should take into account the timing of surgery and radiotherapy, and the size and anatomical site of the tumour.

Aged↗

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

The use of conformal radiotherapy and the selection of radiation dose in T1 or T2 low or intermediate risk prostate cancer - a systematic review.

BACKGROUND AND PURPOSE: The purpose was to develop a systematic review that would address the following questions: (a) when single-modality treatment external-beam radiotherapy is selected as the modality of choice, what is the role of three-dimensional (3D) conformal radiotherapy in treating clinically localized (T1, T2/NO, NX/MO) prostate cancer? The outcomes of interest are biochemical freedom from failure (bNED) rates, clinical recurrence-free survival, disease-specific survival and acute and late toxicity; (b) what is the appropriate dose and fractionation prescription in this clinical setting? MATERIALS AND METHODS: A systematic review of the English published literature was undertaken to provide evidence relevant to the above outcomes. RESULTS: One randomized controlled trial comparing conventional radiotherapy to conformal therapy with dose escalation reported bNED rates. Three additional randomized controlled trials reported acute or chronic late outcome assessments. Additionally, phase II studies of dose escalation in sequential patient cohorts and non-randomized comparative assessments of dose-response and bNED rates in controlled analyses were reviewed. There is convincing evidence from randomized trials that the use of conformal therapy reduces acute and late treatment-related morbidity. There is preliminary evidence suggesting that when external-beam therapy alone is used to treat patients, conformal therapy with dose-escalation is more efficacious than doses of 70Gy. The increased efficacy appears to be predominantly seen in the subset of patients with intermediate-risk disease (PSA 10-20). There is conflicting evidence of the efficacy of dose-escalation in patients with low initial PSA (<10) and in patients with initial PSA greater than 20. Conformal radiotherapy at a dose of 78Gy appears to be relatively safe with no increase in acute or late effects compared with conventional treatment (up to 70Gy) so long as appropriate technological principles are considered. CONCLUSIONS: Patients who have external-beam radiotherapy should be treated using a 3D conformal technique. Patients with intermediate-risk disease (PSA 10-20) who are treated with external-beam radiotherapy alone should be offered doses of 75-78Gy in 180-200cGy fractions.

Disease-Free Survival↗

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

A dose-volume histogram analysis of the seminal vesicles in men treated with conformal radiotherapy to 'prostate alone'.

BACKGROUND AND PURPOSE: There is no consensus on whether the seminal vesicles should be included in the clinical target volume (CTV) for radiotherapy of localized prostate cancer. To inform the debate, we have undertaken a dose-volume histogram (DVH) analysis of the seminal vesicles in patients treated with escalated dose conformal radiation to 'prostate alone'. MATERIAL AND METHODS: Twenty-five consecutive patients receiving conformal radiation to the prostate, to a dose of 75.6 Gy in 42 daily fractions, were studied. The CTV was defined as the prostate only, and the planning target volume (PTV) was defined by a 10 mm margin, except posteriorly where the margin was 7 mm. DVHs were calculated for the entire seminal vesicles, and for 6 mm segments through the seminal vesicles. RESULTS: Incorporating a correction for organ motion, the D90 (minimum dose received by 90% of the volume of interest) for the most inferior 6 mm volume of the seminal vesicles (SV1) ranged from 25 to 70 Gy, and the percentage volume of SV1 receiving 50 Gy ranged from 47-100%. Using a D90 of 50 Gy as a cut-off, eight of the 25 patients had unacceptably low-dose coverage of SV1. CONCLUSIONS: Escalated dose conformal radiation to the 'prostate alone' does not ensure adequate dose coverage of even the most inferior 6 mm of the seminal vesicles. We consider such treatment acceptable in patients at low risk of seminal vesicle involvement (T1/2ab, Gleason < or = 7, PSA < 10 ng/ml). In higher risk patients, if it is deemed necessary to treat the possibility of sub-clinical seminal vesicle involvement, this should be reflected in the definition of the CTV.

Dose-Response Relationship, Radiation↗

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↗

PubMedDate not supplied

Posttreatment complications of early-stage prostate cancer patients: brachytherapy versus three-dimensional conformal radiation therapy.

PURPOSE: The purpose of this study was to compare treatment complications for early-stage prostate cancer managed by either brachytherapy or three-dimensional conformal radiotherapy (3D-CRT). MATERIALS AND METHODS: [corrected] Records were reviewed for 86 men treated with transperineal interstitial permanent prostate brachytherapy and for 76 men treated with dose-escalated (75.6-Gy) six-field 3DCRT between 1998 and 2000. Median ages were 65 and 66 years, respectively; median Gleason scores were 6 and 7; baseline prostate-specific antigen levels were 6.1 and 9.0 ng/mL; and the follow-up period was 42 months. In the urinary domain, patients who underwent brachytherapy recorded an International Prostate Symptom Score prospectively at baseline, as well as 3 months and every 6 months following, whereas patients who underwent 3D-CRT were assigned a Radiation Therapy Oncology Group (RTOG) late toxicity score at similar time intervals. In the bowel domain, RTOG late toxicity score was used for both groups, and physician-dictated notes were used to assess sexual function. All patients who underwent brachytherapy were prescribed tamsulosin (Flomax) to manage urinary symptoms for a minimum of 3 months after treatment. RESULTS: With respect to urinary symptoms, a direct comparison cannot be made between the International Prostate Symptom Score and the RTOG late toxicity score. Nonetheless, it was evident that patients who underwent brachytherapy had more severe urinary sequelae in the months after implantation. Tamsulosin was still being used by 78% of patients at 6 months, decreasing to 55% at 1 year and 27% at 2 years. Intermittent self-catheterization was required at 6 months after treatment by 5% of patients who underwent brachytherapy, and a transurethral resection of the prostate was performed in one of these patients at 12 months. In patients who underwent 3D-CRT, 14% used tamsulosin at some point in the follow-up period and none required catheterization or transurethral resection of the prostate. In the bowel domain, 20% of patients who underwent brachytherapy experienced grade 1 gastrointestinal toxicity, most within the first 12 months of follow-up, compared with 30% grade 1 or 2 gastrointestinal scores in the 3D-CRT group (peaking in the second year after treatment). In the sexual domain, 9% of patients who underwent brachytherapy who were previously potent reported a loss of potency by 18 months, compared with 53% of patients who underwent 3D-CRT. Without the help of sildenafil (Viagra), these figures rose to 24% and 58%. CONCLUSIONS: 3D-CRT is associated with fewer urinary symptoms, whereas brachytherapy has a more favorable toxicity profile for bowel and sexual function. In the absence of a randomized clinical trial, such a comparison can be helpful both in counseling patients as to what to expect from either treatment and in facilitating their treatment decision process.

Aged↗