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Biomedical subjects

R C Leonard

Publications and source records attributed to R C Leonard.

At least 37 records · Page 2Linked to original sources
PubMed1999

Locally advanced breast cancer: the outcome of primary polychemotherapy based on infusional 5 fluorouracil.

Over a 5-year period, 75 patients with locally advanced breast cancer presenting to the Edinburgh Breast Unit were managed with a policy of infusional primary chemotherapy. For 65 patients, the regimens comprised infusional 5 fluorouracil with anthracycline and/or either cyclophosphamide or cisplatinum (AcF, CAF or ECF) whilst 10 older patients had CMF-inf. The overall activity and tolerability for the regimens was good with a 76% objective response rate including 15% clinical complete responses. Surgery was possible in 64% and pathological complete responses confirmed in 7 (9.3%). Median disease free survival (DFS) is 5.23 years. Factors predicting for DFS or Overall Survival (OS) were assessed in this small group and ER positive patients did better than ER negative although there was surprisingly no negative DFS or OS association with inflammatory disease or advancing age. We found a paradoxical interaction with use of post-chemotherapy tamoxifen which was significantly associated with poorer DFS and OS overall and in the ER negative subgroups.

Journal Article↗
PubMed1999

Reducing uncertainty in the derivation and application of health guidance values in public health practice. Dioxin as a case study.

We were requested by the U.S. Environmental Protection Agency (EPA) to clarify the relationships among the minimal risk level (MRL), action level, and environmental media evaluation guide (EMEG) for dioxin established by the Agency for Toxic Substances and Disease Registry (ATSDR). In response we developed a document entitled "Dioxin and Dioxin-Like Compounds in Soil, Part I: ATSDR Interim Policy Guideline"; and a supporting document entitled "Dioxin and Dioxin-Like Compounds in Soil, Part II: Technical Support Document". In these documents, we evaluated the key assumptions underlying the development and use of the ATSDR action level, MRL, and EMEG for dioxin. We described the chronology of events outlining these different health guidance values for dioxin and identified the areas of uncertainty surrounding these values. Four scientific assumptions were found to have had a great impact on this process; these were: (1) the specific uncertainty factors used, (2) the toxicity equivalent (TEQ) approach, (3) the fractional exposure from different pathways, and (4) the use of body burdens in the absence of exposure data. This information was subsequently used to develop a framework for reducing the uncertainties in public health risk assessment associated with exposure to other chemical contaminants in the environment. Within this framework are a number of future directions for reducing uncertainty, including physiologically based pharmacokinetic modeling (PBPK), benchmark dose modeling (BMD), functional toxicology, and the assessment of chemical mixture interactions.

Benchmarking↗
PubMed1999

Validation of Tu's cardiac surgical risk prediction index in a Western Australian population.

Tu's cardiac surgical risk prediction index for a Western Australian population was examined in a prospective observational cohort study. Risk score and outcome data were collected for 367 consecutive patients. Logistic regression analysis for Tu score prediction of hospital mortality and linear regression analysis for prediction of ICU and hospital stays were performed. The Tu index accurately predicted mortality rates (P = 0.002, odds ratio 1.46). The linear regression analyses of Tu score on ICU and hospital stays showed an excellent fit (P = 0.0001). The area under the receiver-operating characteristic curve for prolonged ICU stay was 0.75. The Tu risk index is valid for a Western Australian cardiac surgical population and practice.

Aged↗
PubMed1999

Investigation of endometrial abnormalities in asymptomatic women treated with tamoxifen and an evaluation of the role of endometrial screening.

PURPOSE: Tamoxifen is the most commonly prescribed adjuvant therapy for women with breast cancer. It has agonist activity on the endometrium and is associated with an increased risk of endometrial cancer. The aim of this study was to evaluate whether screening with transvaginal ultrasound (TV USS) with or without hysteroscopy is worthwhile. PATIENTS AND METHODS: A total of 487 women with breast cancer, 357 treated with tamoxifen and 130 controls, were screened with TV USS, and endometrial thickness was measured. Women with thickened endometrium underwent outpatient hysteroscopy. RESULTS: Length of time on tamoxifen ranged from 5 to 191 months (mean, 66 months), and endometrial thickness ranged from 1 to 38 mm (mean, 7.3 mm). Women treated with tamoxifen had significantly thicker endometrium than did controls (P <.0001). There was a statistically significant (P <.0001) positive correlation between length of time on tamoxifen and endometrial thickness. One hundred forty-five women had endometrium greater than 5 mm on USS, and 134 underwent successful outpatient hysteroscopy, 61 of whom had atrophic endometrium, resulting in a 46% false-positive scan rate. The remaining women all had benign features to explain the USS findings. CONCLUSION: TV USS detects a high incidence (41%) of apparent endometrial thickening in women treated with tamoxifen, although 46% had atrophic endometrium on further assessment, and none of the remaining asymptomatic women had significant lesions. Length of time on tamoxifen relates to endometrial thickening as measured by TV USS. TV USS is a poor screening tool because of the high false-positive rate. The low frequency of significant findings suggests that endometrial screening in asymptomatic women is not worthwhile.

Adult↗
PubMed1999

Late outcome from percutaneous tracheostomy using the Portex kit.

OBJECTIVE: To assess late outcome following percutaneous tracheostomy using the Portex kit (Hythe, Kent, UK). DESIGN: Prospective observational cohort study. SETTING: Teaching hospital. PATIENTS: Forty-nine consecutive patients who underwent percutaneous tracheostomy in the ICU using the Portex kit and who survived 6 months after the procedure. INTERVENTIONS: Questionnaires regarding six symptoms were sent to all 49 surviving patients; the 39 respondents were invited to attend for review. Thirteen patients underwent pulmonary function testing, of whom 10 also underwent fiberoptic laryngotracheoscopy under local anesthesia. RESULTS: The most common symptom was a minor change in voice. One patient had required treatment for symptomatic tracheal stenosis by the time of review; one was referred for revision of a tethered scar. Pulmonary function testing was easily performed by all patients and revealed no evidence of upper airway obstruction. Tracheoscopy likewise showed no evidence of tracheal stenosis. CONCLUSIONS: One of 49 patients had developed tracheal stenosis. None of the patients attending for detailed review showed any sign of late complications other than one tethered scar.

APACHE↗
PubMed1999

Lessons from the use of aromatase inhibitors in the neoadjuvant setting.

Postmenopausal patients with oestrogen receptor-positive locally advanced T4b, N0-1, M0 and large operable breast cancers T2>3 cm, T3, T4, N0-1 and M0 have been treated with 2.5 mg letrozole (12 patients), 10 mg letrozole (12 patients), 1 or 10 mg anastrozole (24 patients) and 20 mg tamoxifen (65 patients). There was no apparent difference in response rate between 2.5 and 10 mg letrozole. Only 17 patients with anastrozole have so far completed the 3-month treatment period. Median clinical, mammographic and ultrasound reductions in tumour volumes for patients treated with letrozole were 81% (95% confidence interval (CI) 66-88), 77% (95% CI 64-82) and 81% (95% CI 69-86) respectively and for anastrozole, values were 87% (95% CI 59-97), 73% (95% CI 58-82) and 64% (95% CI 52-76) respectively. This compares with a median reduction in tumour volume for tamoxifen-treated patients as assessed by ultrasound of 48% (95% CI 27-48). There were seven complete clinical responses (CR), sixteen patients who achieved 50% or greater reduction in tumour volume (PR) and one no change (NC) for letrozole and four CRs, twelve PRs and one progressive disease for anastrozole. Best radiological responses were one CR, twenty PRs and three NCs for letrozole and one CR, fifteen PRs and one NC for anastrozole. This study has shown that the new aromatase inhibitors, letrozole and anastrozole, are highly effective agents in the neoadjuvant setting and they should now be compared with tamoxifen as first-line treatment in a randomised study.

Aged↗
PubMed1998

Antitumour activity and schedule dependency of 8-chloroadenosine-3',5'-monophosphate (8-ClcAMP) against human tumour xenografts.

8-Chloroadenosine-3',5'-monophosphate (8-ClcAMP) is a novel antitumour agent currently undergoing phase I clinical trials in several European centres. In this study, its antitumour activity against human tumour xenografts and its dependence on schedule were investigated. When administered by continuous infusion at doses of 100 or 50 mg/kg/day to nude mice bearing human tumour xenografts, 8-ClcAMP inhibited the growth of the HT 29 colorectal, ZR-75-1 breast, HOX 60 and PE04 ovarian and PANC-1 pancreatic carcinoma xenografts. However, these infusion schedules produced hypercalcaemia and severe weight loss. In an attempt to optimise antitumour activity and minimise toxicity, several other schedules were studied. In comparison with continuous administration of 8-ClcAMP at 50 mg/kg/day for 14 days which, although producing complete growth inhibition in the HOX 60 model, was associated with a marked body weight loss, schedules in which the infusion was interrupted (infusion on either days 0-4; 7-11 or days 0-2; 6-8) produced minimal weight loss but also reduced antitumour activity. However, co-administration of salmon calcitonin with continuous infusion of 8-ClcAMP prevented both hypercalcaemia and body weight loss in 3/6 animals while still producing marked inhibition of tumour growth. These data indicate that 8-ClcAMP has broad-spectrum antitumour activity and the major side-effect of hypercalcaemia may at least in part be ameliorated by the use of salmon calcitonin.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1997

CHOP-based chemotherapy is as effective as alternating PEEC/CHOP chemotherapy in a randomised trial in high-grade non-Hodgkin's lymphoma. Scotland and Newcastle Lymphoma Group.

The aim of this study was to test whether survival for patients with high-grade non-Hodgkin's lymphoma (NHL) can be improved with a non-cross-resistant regimen as compared to a CHOP-based regimen. This is a multicentre study comprising 325 adult patients, median age 58 years, with high-grade non-Hodgkin's lymphoma: patients of any age and performance status were eligible provided they were able to receive the drugs in the regimens. Patients were randomised to either B-CHOP-M (bleomycin, cyclophosphamide, doxorubicin, vincristine, prednisolone and methotrexate) or PEEC-M (methylprednisolone, vindesine, etoposide, chlorambucil and methotrexate) alternating with B-CHOP-M. At a median follow-up of 9 years, there was no significant difference in overall survival or disease-free survival between the two arms. Toxicities for the two regimens were equivalent. This study confirms that for relatively unselected patients with high-grade non-Hodgkin's lymphoma, an alternating multidrug regimen does not improve upon the results obtained with B-CHOP-M.

Adult↗
PubMed1997

Primary systemic therapy for operable breast cancer--10-year survival data after chemotherapy and hormone therapy.

Between 1984 and 1990, 94 women presenting to the Edinburgh Breast Unit with operable breast cancer of 4 cm or greater in diameter (T2, T3, N0, N1, M0) were given preoperative systemic therapy. Initially, all women received hormone therapy, with CHOP (cyclophosphamide 1 g m(-2), doxorubicin 50 mg m(-2), vincristine 1.4 mg m(-2) to a maximum of 2 mg and prednisolone 40 mg per day orally for 5 days) chemotherapy being administered to those who failed to respond by 3 months. After April 1987, first-line hormone therapy was only offered to women with oestrogen receptor (ER)-moderate/-rich (> 20 fmol mg(-1) protein) tumours, and CHOP was reserved for those women whose tumours failed to respond to hormone therapy and for those with ER-negative/-poor tumours. Response data have been published previously (Anderson et al, 1991). After a median follow-up of 7.5 years, there is no difference in survival between those women given initial hormone therapy and those given chemotherapy, with neither group having yet reached its median survival. The two key factors that predicted for a poor survival were the number of involved axillary nodes after preoperative systemic therapy (P < 0.00001) and a lack of response to preoperative therapy (P < 0.05). These data suggest that many women with ER-moderate/-rich tumours will have a good prognosis after preoperative hormone therapy alone. However, it is possible to identify, by their post-systemic therapy axillary node status, a group of women who still have an appalling prognosis after preoperative chemotherapy or hormone therapy.

Adult↗
PubMed1997

The advancement of high-dose chemotherapy and dose intensification schedules.

Breast cancer is the most common female cancer--one woman in 12 will have breast cancer at some stage during her life. Early-stage breast cancer is often curable; however, the prognosis is much worse in patients with multiple lymph node involvement or metastatic disease. The overall survival at five years is approximately 60% in women with positive lymph nodes, decreasing to 27%-44% when more than 10 lymph nodes are involved. After metastatic relapse, the mainstay of treatment is palliative. However, recent advances in supportive care have facilitated investigation into the use of dose-intensive chemotherapy regimens. The advancement of high-dose chemotherapy in breast cancer and results from clinical trials in both metastatic disease and the adjuvant setting are reviewed here. The true benefit of high-dose chemotherapy in breast cancer continues to be investigated. It is hoped that the results of worldwide, randomised clinical trials, due within the next three to five years, will provide a clearer indication of the value of high-dose chemotherapy, its costs and the patients whom it will benefit most.

Antineoplastic Agents↗
PubMed1996

Definition and refinement of a region of loss of heterozygosity at 11q23.3-q24.3 in epithelial ovarian cancer associated with poor prognosis.

Previous cytogenetic and loss of heterozygosity (LOH) data suggest that disruption of chromosome 11q23-qter occurs frequently in epithelial ovarian cancer and is associated with an adverse clinicopathological phenotype. Ten polymorphic microsatellite repeat loci were analyzed by PCR from the 11q22-q25 region between D11S35 and D11S968 in 40 ovarian tumors (including 31 epithelial ovarian cancers). Two distinct regions of loss were detected, suggesting possible sites for genes involved in epithelial ovarian neoplasia: a large centromeric region between D11S35 and D11S933 (11q22-q23.3) and a telomeric 8.5-Mb region lying between D11S934 and D11S1320 (11q23.3-24.3) not previously defined. LOH of the latter region but not the former one was significantly associated with poor survival, despite all tumors in this study having LOH somewhere on chromosome 11. This analysis provides a starting point for positional cloning.

Carcinoma↗
PubMed1996

High-dose chemotherapy for breast cancer.

What can we conclude and hope to see in the next few years? Laboratory studies and imperfect retrospective analysis of conventional chemotherapy have created a climate of active interest to experiment with dose-intensive chemotherapy. There seems to be a consensus in favour of combination alkylating agents to maximise anticancer and rescuable antimarrow stem cell effects, whilst producing sublethal second-organ toxicity. PBPC has replaced ABMT as the routine rescue technique, on grounds of cost and recovery time. The mature results of this changed technology for support have yet to be seen in terms of the risks of late, poor engraftment and the potential benefits in terms of acute complications (faster engraftment) and tumour kill (reduced tumour contamination?). Whilst experiments continue to examine the impact of tumour contamination of blood harvests or BM harvests, inadequate attention has been paid in metastatic disease to patient selection. There seems to be a continuing growth of interest in multiple high-dose therapy regimens using stem cells collected earlier in the therapy to rescue sequential myeloablative treatments. This possibility has been realised by the stem cell technology and is being pursued with enthusiasm and with promising early results. Media-driven public interest in this increasingly political disease is pushing us to 'do more'. In future years, our worst nightmares may be realised if this means aping the experience of Halsted's disciples, "don't test, just believe"--the economic and human costs of high-dose treatment cannot justify our avoiding the rigorous examination of controlled trials.

Antineoplastic Agents↗