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Biomedical subjects

A Howell

Publications and source records attributed to A Howell.

At least 73 records · Page 4Linked to original sources
PubMed1997

Serum 1,25-dihydroxyvitamin D may be related inversely to disease activity in breast cancer patients with bone metastases.

1,25-dihydroxyvitamin D (1,25-(OH)2D) stimulates differentiation and controls proliferation in breast cancer cells. The role of endogenous 1,25-(OH)2D and its relation to PTH related protein (PTHrP) during the progression of breast cancer is not known; we therefore investigated these hormones in two studies. In a cross-sectional study of patients with breast cancer at different stages of disease, serum 1,25-(OH)2D levels (mean +/- SE) were highest in early disease (102 +/- 3.7 pmol/L), fell in normocalemic patients with bone metastases (52 +/- 5.3 pmol/L; P < 0.01), and were lowest in hypercalcemic patients (33 +/- 5.6 pmol/L; P < 0.001). PTHrP was detectable in the serum of only one normocalcemic patient with progressive metastases but was present in 11 of the 12 hypercalcemic patients, thus PTHrP did not stimulate 1,25-(OH)2D synthesis. In a 6-month longitudinal study of normocalcemic patients with bone metastases undergoing hormonal therapy, serum 1,25-(OH)2D concentrations fell in patients whose disease progressed (P = 0.0056), but remained constant in those who were stable or responded to treatment. These changes in 1,25-(OH)2D preceded clinical signs of progression and predicted disease response. In the progressive group, five of whom died during the study, 1,25-(OH)2D decreased between the initial and final samples, PTH fell significantly from 24.8 to 13.5 ng/L (P = 0.025), serum calcium rose from 2.27 to 2.39 mmol/L (P = 0.017), and the urinary calcium/creatinine ratio rose from 0.37 to 0.68 (P = 0.046). PTH and 1,25-(OH)2D were significantly correlated in the final samples from this group, Spearman's rank correlation = 0.80, P = 0.022. The results indicate that normocalcemia in these patients is maintained, at the expense of suppressing PTH and 1,25-(OH)2D, in the face of increased calcium released from lytic lesions in bone. Loss of the antiproliferative effects of 1,25-(OH)2D may then permit more rapid secondary growth of the tumor.

Bone Neoplasms↗
PubMed1997

Antiestrogens: future prospects.

Tamoxifen is currently the endocrine therapy of choice for early and advanced breast cancer. Attempts to improve the therapeutic efficacy have included altering the triphenylethylene ring structure of tamoxifen, forming new nonsteroidal ring structures or creating steroidal estradiol analogs with greater antiestrogenic activity. There are now six nonsteroidal compounds either on the market or in clinical development and one steroidal "pure" antiestrogen has entered clinical trials. A number of these agents show improved estrogen-receptor binding affinity, antiestrogenic activity, and/or antitumor activity compared with tamoxifen. Preclinical and clinical data on these compounds are discussed and compared with tamoxifen when possible.

Estrogen Antagonists↗
PubMed1997

ARIMIDEX: a potent and selective aromatase inhibitor for the treatment of advanced breast cancer.

Aromatase inhibitors have been available for a number of years and their ability to reduce circulating estradiol levels has been shown to produce clinical benefit in women with advanced breast cancer. Until recently, the only commercially available aromatase inhibitor was aminoglutethimide. Although aminoglutethimide has been shown to be efficacious in the treatment of advanced breast cancer, it does cause significant toxicity and requires the use of concomitant hydrocortisone therapy. Anastrozole is one of a new class of potent aromatase inhibitors able to suppress estradiol to the limit of detection of sensitive assays without suppressing adrenal steroidal synthesis. Two large clinical trials (n = 764) conducted in the U.S.A. and in Europe evaluated two doses of anastrozole, 1 and 10 mg a day, compared to megesterol acetate, 40 mg four times a day, in postmenopausal women who had progressed while on tamoxifen. Response rates and time to progression with anastrozole were similar to those of megesterol acetate. Objective responses (CR + PR) were 10.3%, 8.9% and 7.9% in the 1 and 10 mg of anastrozole and megesterol acetate treatment groups, respectively. Another 25.2%, 22.6% and 26.1% had stable disease for over 24 weeks on 1, 10 mg anastrozole and megesterol acetate, respectively. Anastrozole and megesterol acetate were well tolerated; however, more patients had significant weight gain on megesterol acetate than with anastrozole treatment. The weight gain seen with megesterol acetate continued to increase over time. Anastrozole has a better therapeutic index (fewer side-effects) and has recently been approved by the FDA and a number of other regulatory agencies around the world for the treatment of advanced breast cancer.

Anastrozole↗
PubMed1996

Tumour angiogenesis as a prognostic marker in infiltrating lobular carcinoma of the breast.

The importance of angiogenesis, assessed by tumour microvessel density, as a marker of survival was examined in 160 patients with infiltrating lobular carcinoma of the breast (ILC). The median follow-up was 5.1 years. Of these patients, 46 were node-negative, 59 were node-positive, and in 55 the pathological lymph node status was not known. Tumour sections were immunohistochemically stained with Factor VIII-related antibody. Microvessels were identified using previously recommended methodology and counted in three separate fields, selected from areas of highest vascularity, at x 200 magnification (field area = 0.785 mm2). Only the highest count was considered in the analysis. No association was found between microvessel density and age, menopausal status, tumour size, histological subtype, peritumoural vessel invasion, and lymph node involvement at presentation. There was no association between microvessel density and overall survival or relapse-free survival. These results suggest that microvessel density assessment, using currently recommended methods, is unlikely to be of prognostic value in ILC.

Adult↗
PubMed1996

Effects of short-term antiestrogen treatment of primary breast cancer on estrogen receptor mRNA and protein expression and on estrogen-regulated genes.

Effects of the pure antiestrogen ICI182780 and tamoxifen on ER-protein, ER-mRNA, and estrogen-regulated mRNA expression were analysed using matched pretreatment core-cut biopsies and post-treatment mastectomy samples from 43 ER positive human breast cancers. Sixteen controls received either no preoperative treatment (n = 9) (7 days) or placebo (n = 7) (median 21 days) prior to primary surgery. Nineteen patients received ICI182780 6 mg/day (n = 10) or 18 mg/day (n = 9) for 7 days. Eight patients were given preoperative tamoxifen (4 x 40 mg-day 1, 20 mg/day thereafter, median 21 days). ER-protein expression was assessed on pre and post treatment samples by immunocytochemistry. ER, pS2, pLIV1, and actin-mRNA expression was determined by northern analysis on post-treatment samples only. ER-mRNA levels were similar to controls following ICI182780 or tamoxifen treatment. However ER-protein levels were significantly suppressed by ICI182780, particularly at the higher dosage (p = 0.0013). Tamoxifen had no significant effect on ER-protein levels. The ER-mRNA and ER-protein contents of control tumors were linearly related (Spearman r = 0.719, p = 0.006). A similar relationship between pretreatment protein and post ICI182780 treatment mRNA levels was observed (r = 0.652, p = 0.005). However, comparison of post ICI182780 treatment protein and mRNA results shows a loss of linearity through a reduction in protein without concurrent loss of mRNA (r = 0.28, p = 0.257). pS2 mRNA hybridization was lower in ICI182780 treated samples than controls (Mann-Whitney p = 0.035) but was unaffected by tamoxifen. pLIV1 mRNA hybridization was uninfluenced by either treatment. Short term exposure of breast tumors to ICI182780 appears to produce a greater inhibition of estrogen-induced transcriptional events than tamoxifen. These effects appear to occur without a concurrent reduction in ER mRNA levels.

Antineoplastic Agents, Hormonal↗
PubMed1996

A randomised trial comparing two doses of the new selective aromatase inhibitor anastrozole (Arimidex) with megestrol acetate in postmenopausal patients with advanced breast cancer.

The aim of this study was to compare the efficacy and tolerability of the new aromatase inhibitor 'ARIMIDEX' (anastrozole) with megestrol acetate in the treatment of advanced breast cancer in postmenopausal women. Anastrozole is a new potent and highly selective non-steroidal aromatase inhibitor. We conducted a prospective randomised trial comparing two doses of anastrozole (1 and 10 mg orally once daily) with megestrol acetate (40 mg orally four times daily) in postmenopausal patients with advanced breast cancer who progressed after prior tamoxifen therapy. All patients were analysed for efficacy as randomised (intention to treat) and for tolerability as per treatment received. Of the 378 patients who entered the study, 135 were randomised to anastrozole 1 mg, 118 to anastrozole 10 mg, and 125 patients to megestrol acetate. After a median follow-up of 192 days, response rate which included complete response, partial response and patients who had disease stabilisation for 6 months or more was 34% for anastrozole 1 mg, 33.9% for anastrozole 10 mg and 32.8% for megestrol acetate. There were no statistically significant differences between either dose of anastrozole and megestrol acetate in terms of objective response rate, time to objective progression of disease or time to treatment failure. The three treatments were generally well tolerated, but more patients on megestrol acetate reported weight gain, oedema and dyspnoea as adverse events while more patients on anastrozole reported gastro-intestinal disorders, usually in the form of mild transient nausea. Patients on anastrozole did not report higher incidences of oestrogen withdrawal symptoms. Anastrozole is an effective and well tolerated treatment for postmenopausal patients with advanced breast cancer. The higher 10 mg dose did not result in additional clinical benefit, but was well tolerated reflecting the good therapeutic margin with anastrozole. Based on this data, anastrozole 1 mg should be the recommended therapeutic dose.

Adult↗
PubMed1996

New endocrine therapies for breast cancer.

How do the new endocrine therapies stand up to the aims of modern endocrine therapy outlined in Table 1? We wish to see increased efficacy, decreased toxicity and improved general health in women taking a new agent. None of the new non-steroidal anti-oestrogens have shown unequivocal evidence of improved efficacy in the clinic to mirror their improved profiles over tamoxifen in preclinical studies. We know that toremifene is equivalent to tamoxifen, but we do not have any phase III data from the other four compounds in development. The specific steroidal antioestrogen, ICI 182,780, looks very promising, but is early in its developmental programme. The new aromatase inhibitors are likely to prove equal to tamoxifen or progestagens, but it is disappointing that improved oestrogen suppression has not led, to date, to improved efficacy. No comment can be made about adjuvant or preventative therapy for any of the new agents, although trials are planned for the new aromatase inhibitors in this clinical situation. Currently, the antiprogestins are disappointing and we will need to wait a considerable time for new agents in preclinical testing to reach the clinic. Many of the new agents are associated with decreased toxicity. It is likely that the NSAEs will be equitoxic with tamoxifen. The steroidal antioestrogen looks particularly non-toxic as do the new aromatase inhibitors, and thus we have an advance in terms of reduced toxicity. The effects of the new agents on the uterus, lipids and bone are in the early stages of testing. Raloxifene, ICI 182,780 and the new aromatase inhibitors are expected to have no proliferative effects on the endometrium, but only the new NSAEs are expected to have beneficial cardiovascular and skeletal effects. If the steroidal anti-oestrogens and new aromatase inhibitors become adjuvant therapies of choice, other agents to prevent osteoporosis and cardiovascular events may also have to be administered.

Animals↗
PubMed1996

Pharmacokinetics, pharmacological and anti-tumour effects of the specific anti-oestrogen ICI 182780 in women with advanced breast cancer.

We have assessed the pharmacokinetics, pharmacological and anti-tumour effects of the specific steroidal anti-oestrogen ICI 182780 in 19 patients with advanced breast cancer resistant to tamoxifen. The agent was administered as a monthly depot intramuscular injection. Peak levels of ICI 182780 occurred a median of 8-9 days after dosing and then declined but were above the projected therapeutic threshold at day 28. Cmax during the first month was 10.5 ng/ml-1 and during the sixth month was 12.6 ng ml-1. The AUCs were 140.5 and 206.8 ng day ml-1 on the first and sixth month of dosing respectively, suggesting some drug accumulation. Luteinising hormone (LH) and follicle-stimulating hormone (FSH) levels rose after withdrawal of tamoxifen and then plateaued, suggesting no effect of ICI 182780 on the pituitary-hypothalamic axis. There were no significant changes in serum levels of prolactin, sex hormone-binding globulin (SHBG) or lipids. Side-effects were infrequent. Hot-flushes and sweats were not induced and there was no apparent effect of treatment upon the endometrium or vagina. Thirteen (69%) patients responded (seven had partial responses and six showed "no change' responses) to ICI 182780, after progression on tamoxifen, for a median duration of 25 months. Thus ICI 182780, given by monthly depot injection, and at the drug levels described, is an active second-line anti-oestrogen without apparent negative effects on the liver, brain or genital tract and warrants further evaluation in patients with advanced breast cancer.

Aged↗
PubMed1996

Indices of differential endometrial: myometrial growth may be used to improve the reliability of detecting endometrial neoplasia in women on tamoxifen.

The aim of this study was to test the hypothesis that the use of indices of differential endometrial: myometrial growth may be a non-invasive method of improving the reliability of detecting endometrial neoplasia in women on tamoxifen. Thirty postmenopausal women were involved in this prospective study. Nineteen had been treated with tamoxifen for 2 years or more, and eleven were age- and ponderal index-matched controls who had never been exposed to tamoxifen and who were non-smokers. Transvaginal ultrasonography and color Doppler imaging were performed, to measure the length, anteroposterior diameter, uterine sagittal area, endometrial thickness and uterine blood flow (using the pulsatility index and the resistance index as measures of uterine blood flow impedance). The anteroposterior diameter: endometrial thickness ratio and product, and the saggital area: endometrial thickness ratio and product were used as indices of differential endometrial: myometrial growth. The predictive values (sensitivity, specificity, positive and negative predictive values) of each index were calculated using established criteria. For the purpose of analysis the women were allocated to three groups: controls (group 1); women on tamoxifen without endometrial neoplasia (group 2) and women on tamoxifen who developed endometrial neoplasia (group 3). The mean age was similar in the three groups as was the duration of tamoxifen treatment in groups 2 and 3. Analysis of the decision matrix based on increased endometrial thickness (> 5 mm) alone revealed good sensitivity (100%) and negative predictive value (100%) but poor specificity (46.15%) and positive predictive value (26.32%). However, when the indices of differential endometrial: myometrial growth were taken into consideration, the sensitivities and negative predictive values were similar but the specificities and positive predictive values were significantly improved, indicating an improvement in the reliability of predicting the development of endometrial neoplasia.

Aged↗
PubMed1996

Mobilisation kinetics of primitive haemopoietic cells following G-CSF with or without chemotherapy for advanced breast cancer.

BACKGROUND: The objective of this study was to determine the optimal conditions for blood progenitor cell harvest for transplantation, with main emphasis on the mobilisation kinetics of primitive, marrow repopulating cells. PATIENTS AND METHODS: Sixteen patients with advanced breast cancer were treated with 4 cycles of dose escalating FAC chemotherapy (5-fluorouracil, adriamycin, cyclophosphamide) each followed by 10 micrograms/kg/d G-CSF for 13 days. We assessed the number of colony-forming cells (CFC), and estimated the long-term culture initiating cells (LTC-IC) and CD34+ cells during the recovery phase of cycle 1 and 4 of chemotherapy, and during additional periods of G-CSF administration either preceding or following the full course of chemotherapy. RESULTS: The highest peak numbers of CFC per ml of blood (median 10489, range 860-39282) were mobilised after the first cycle of chemotherapy. The lowest peak numbers of CFC were obtained during the recovery phase from cycle 4 (median 4739, range 40-26789). In contrast, the numbers of CD34+ cells per ml of blood were significantly higher in cycle 4 (median 650, range 30-2600 x 10(2)) compared to those of cycle 1 (median 240, range 20-770 x 10(2)). The peak numbers of CFC mobilised by G-CSF before commencement and after the cessation of chemotherapy were equivalent, with a median of 5470 (range 1056-25669) and 5948 (range 2710-38975) per ml of blood, respectively. However, while mononuclear cells (MNC) collected at the days of maximal CFC mobilization following G-CSF administration before or after cycle 1 were similar to normal bone marrow MNCs in their ability to generate haemopoiesis when seeded onto performed irradiated stroma, those collected after cycle 4 or during G-CSF administration after the cessation of chemotherapy were markedly compromised in this respect. CONCLUSIONS: Our results indicate that repeated cycles of FAC chemotherapy followed by G-CSF result in a far lower number of LTC-IC than of CFC mobilised into the circulation. Furthermore although the combination of chemotherapy and G-CSF mobilised the highest numbers if CFC, G-CSF alone pre-chemotherapy was more effective at mobilising LTC-IC. These data indicate that neither the numbers of CFC mobilised nor the numbers of CD34+ cells are necessarily a reliable indicator for the putative marrow repopulating capability of the blood cells mobilised with chemotherapy plus G-CSF.

Adult↗
PubMed1996

Carcinomatous meningitis in solid tumours.

Carcinomatous meningitis (CM) is an uncommon but devastating complication of malignancy. The management is controversial and clear recommendations cannot be made because: 1) Most series include patients with CM that has arisen from different primary malignancies which are associated with different median survival intervals. 2) There have been no prospective randomised investigations of treatment modalities in patients with CM from a particular tumour type. 3) The definition of response varies from one report to another so that some response rates refer to cytological changes in the CSF while others take clinical, cytological and biochemical parameters into account. 4) Reports include patients with and without parenchymal metastases and the natural history of carcinomatous meningitis in the two situations may differ. The median survival of solid tumour carcinomatous meningitis (excluding leukaemia and lymphoma) is approximately 2-3 months and patients with breast cancer have the longest survival (median 3 months). Currently patients are treated with radiotherapy to part or all of the neuraxis with either intrathecal or intravenous chemotherapy but the relative contribution of these modalities to survival or quality of life remains unknown. Approximately 50% of patients with carcinomatous meningitis die from other causes, including systemic disease. The two most important endpoints for the patient, neurological improvement and overall survival, are seldom used in isolation in the literature. Many reports have focused on surrogate markers of response, namely biochemical and cytological data points but the correlation between clinical status and these parameters is poor because of differences between lumbar and ventricular CSF and disturbances of CSF flow in CM. The current literature does not provide clear guidelines for the treatment of this condition. Multicentre, prospective, randomised trials should be conducted that address questions of most relevance to the patient, namely neurological status and overall survival.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

Anastrozole, a potent and selective aromatase inhibitor, versus megestrol acetate in postmenopausal women with advanced breast cancer: results of overview analysis of two phase III trials. Arimidex Study Group.

PURPOSE: To compare the efficacy and tolerability of anastrozole (1 and 10 mg once daily), a selective, oral, nonsteroidal aromatase inhibitor, and megestrol acetate (40 mg four times daily), in postmenopausal women who progressed following tamoxifen treatment. PATIENTS AND METHODS: Two randomized, double-blind for anastrozole, open-label for megestrol acetate, parallel-group, multicenter trials were conducted in 764 patients. Because both trials were identical in design, an analysis of the combined results was performed to strengthen interpretation of results from each trial. RESULTS: The median follow-up duration was approximately 6 months. The estimated progression hazards ratios were 0.97 (97.5% confidence interval [CI], 0.75 to 1.24) for anastrozole 1 mg versus megestrol acetate and 0.92 (97.5% CI, 0.71 to 1.19) for anastrozole 10 mg versus megestrol acetate. The overall median time to progression was approximately 21 weeks. Approximately one third of patients in each group benefited from treatment. Twenty-seven patients (10.3%) in the anastrozole 1-mg group, 22 (8.9%) in the anastrozole 10-mg group, and 20 (7.9%) in the megestrol acetate group had a complete or partial response, and 66 (25.1%), 56 (22.6%), and 66 (26.1%) patients, respectively, had stable disease for > or = 24 weeks. For all end points, individual trial results were similar to the results of the combined analysis. Anastrozole and megestrol acetate were well tolerated. Gastrointestinal disturbance was more common among patients in the anastrozole groups than the megestrol acetate group; the difference between the anastrozole 10 mg and megestrol acetate groups was significant (P = .005). Significantly fewer patients in the anastrozole 1-mg (P < .0001) and 10-mg (P < .002) groups had weight gain than in the megestrol acetate group. More than 30% of megestrol acetate-treated patients had weight gain > or = 5%, and 10% of patients had weight gain > or = 10%. Patients who received megestrol acetate continued to gain weight over time. CONCLUSION: Anastrozole, 1 and 10 mg once daily, is well tolerated and as effective as megestrol acetate in the treatment of postmenopausal women with advanced breast cancer who progressed following tamoxifen treatment. Moreover, anastrozole therapy avoids the weight gain associated with megestrol acetate treatment.

Adult↗
PubMed1995

Response to a specific antioestrogen (ICI 182780) in tamoxifen-resistant breast cancer.

We treated 19 patients with advanced breast cancer resistant to tamoxifen with a new specific antioestrogen (ICI 182780) which, in animal studies, has no agonist activity. 13 (69%) patients responded (7 had partial responses and 6 showed no change) to monthly intramuscular injections of ICI 182780 after progression on tamoxifen, for a median duration of 18 months with minimum side effects. Preliminary evidence suggests that the agent is without effects on the liver or the hypothalamic-pituitary axis. ICI 182780 appears to be a promising new agent for treatment of advanced and early breast cancer.

Aged↗