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Biomedical subjects

P Neven

Publications and source records attributed to P Neven.

At least 19 recordsLinked to original sources
PubMed2002

Endometrial disorders in 406 breast cancer patients on tamoxifen: the case for less intensive monitoring.

OBJECTIVES: To describe the endometrial appearance in postmenopausal breast cancer patients on tamoxifen and to assess a routine surveillance scheme for endometrial lesions. STUDY DESIGN: Three hundred and seventeen postmenopausal breast cancer women already on tamoxifen at the start of the study (group I) and 89 breast cancer women assessed before any tamoxifen intake (group II) underwent an initial and then yearly scans with transvaginal ultrasonography, followed by an hysteroscopy and biopsy for women with an endometrium thickened above 8mm. Endometrial thickness was also measured in 823 women with no breast cancer nor tamoxifen intake (group III). RESULTS: Initial mean endometrial thickness was 8.2mm in group I, 4.4mm in group II and 3.4mm in group III (P<0.001). Eighteen percent endometrial lesions were found in group I and 3.3% in group II. We observed a significant association between endometrial pathology and both cumulated dose and total duration. Polyps were the most frequent and first to appear pathology. Five cancers were detected in group I, and all of them had taken tamoxifen for more than 3 years. CONCLUSION: Our surveillance scheme could be lightened; an acceptable screening scheme might include a baseline assessment before the start of tamoxifen and, if normal, yearly screening after 3 years of tamoxifen therapy, yearly surveillance for women with an abnormal baseline assessment and immediate investigation for symptomatic women.

Adenocarcinoma↗
PubMed2001

Raloxifene effect on frequency of surgery for pelvic floor relaxation.

OBJECTIVE: To assess the effects of raloxifene therapy on the frequency of surgery for pelvic floor relaxation in postmenopausal women. METHODS: This analysis used safety data through 3 years of treatment from three double-masked, placebo-controlled, randomized trials of raloxifene, which included 6926 postmenopausal women with uteri at entry. Studies 1 and 2 enrolled 969 nonosteoporotic, postmenopausal women who were assigned to 30, 60, or 150 mg per day raloxifene or placebo. Study 3 enrolled 5957 osteoporotic, postmenopausal women randomized to raloxifene 60 or 120 mg per day or placebo. Indications for any reported pelvic operations were identified, including procedures performed for pelvic organ prolapse or urinary incontinence. RESULTS: A total of 34 (1.51%) women in the placebo group and 35 (0.75%) raloxifene-treated women underwent surgical procedures for pelvic floor relaxation. The odds ratio (and 95% confidence interval) for pelvic floor repair in women assigned to raloxifene was 0.50 (0.31, 0.81). Thus, raloxifene therapy was associated with a significantly reduced risk for pelvic floor surgery (P <.005). CONCLUSION: Raloxifene does not increase pelvic floor relaxation. An apparent protective effect on pelvic floor function warrants further investigation.

Aged↗
PubMed2001

Tamoxifen, screening and new oestrogen receptor modulators.

Tamoxifen is a selective oestrogen receptor modulator (SERM) with anti-oestrogenic properties in the breast and oestrogenic effects in tissues such as bone and the cardiovascular system. It is an excellent breast cancer drug for all stages of the disease. Its SERM profile makes it a valuable alternative to hormone replacement therapy, especially for women at high risk of breast cancer. Tamoxifen, however, increases the incidence of benign and malignant lesions of the uterus. Secondary prevention of these, early detection and treatment, is feasible but not cost-effective in breast cancer patients because potential endometrial risks do not outweigh beneficial effects in the breast. This may be different in healthy women with an as yet unknown benefit on breast cancer mortality. We review the literature on the importance of tamoxifen's endometrial lesions and balance available evidence on whether and how best to screen them. In a subset of tamoxifen users it seems advisable to assess the uterine cavity prior to intake with a yearly endometrial assessment as pointed out, starting 3 years after initiation of treatment. In most cases there is endometrial thickening on ultrasonographic assessment and additional tests such as hydrosonography or hysteroscopy are required to confirm an empty atrophic uterus as remains the case in most asymptomatic women on tamoxifen. Newer compounds, such as raloxifene, have a similar SERM profile to tamoxifen but are neutral on the uterus. This has recently been proven by 3 years of endometrial follow-up data. Longer endometrial safety will hopefully confirm these early findings. Whether other SERMs in development are better, and which of them is better for the breast, is to be demonstrated in ongoing studies.

Antineoplastic Agents, Hormonal↗
PubMed2001

Pharmacology of the thromboxane receptor antagonist and thromboxane synthase inhibitor BM-531.

BM-531 (N-tert-butyl-N'-[(2-cyclohexylamino-5-nitrobenzene)sulfonyl]urea), a torasemide derivative, is a novel noncarboxylic thromboxane receptor antagonist and thromboxane synthase inhibitor. Indeed, its affinity for human washed platelet TXA2 receptors labeled with [3H]SQ-29548 (IC50 = 0.0078 microM) is higher than sulotroban (IC50 = 0.93 microM) and SQ-29548 (IC50 = 0.021 microM). Moreover, BM-531 is characterized by a potent antiaggregatory property. Indeed, on one hand, in human citrated platelet-rich plasma BM-531 prevents platelet aggregation induced by arachidonic acid (600 microM) (ED100 = 0.125 microM), U-46619, a stable TXA2 agonist (1 microM) (ED50 = 0.482 microM) or collagen (1 microgram/mL) (percentage of inhibition: 42.9% at 10 microM) and inhibits the second wave of ADP (2 microM)-induced aggregation. On the other hand, when BM-531 is incubated in whole blood from healthy donors, the closure time measured by the recently developed platelet function analyser (PFA-100) is significantly prolonged. In addition, at the concentrations of 10 and 1 microM, BM-531 totally prevents the production of TXB2 by human platelets activated by arachidonic acid. Finally, at 10 microM, BM-531 significantly prevents rat fundus contractions induced by U-46619 but not by prostacyclin. These results suggest that BM-531, which is devoid of the diuretic property of torasemide, can be regarded as a promising antiplatelet agent.

Animals↗
PubMed2000

The immunocytochemical versus cytosol measurement of the oestrogen receptor in invasive breast cancer tissue.

To compare two methods of measurement of oestrogen receptor (ER)-expression in invasive breast cancer tissue. Sections from 299 breast cancer cases were stained for the ER by immunocytochemical assay (ICA), using mouse monoclonal antibody (MAb) NCL-ER-6SF11, and by the dextran-coated charcoal assay (DCC). Concordant results were observed in 230 of the 299 cases (77%), 69 patients had discordant results (kappa=0.537). We found a moderate concordance between ICA and DCC for ER measurement in breast cancer tissue. If we change the golden standard from DCC to ICA, 23% of patients would receive a different therapeutic approach.

Biomarkers, Tumor↗
PubMed2000

Modulation of endometrial transforming growth factor beta (TGFbeta) by tamoxifen.

Transforming growth factor beta (TGFbeta) immunoreactivity was determined in endometria from non-drug-therapy and tamoxifen-treated patients. Sections were scored for pathology and quantity image analysis performed to determine levels of glandular- or fibrosis-associated TGFbeta1. Tamoxifen-treated patients displayed greater levels of endometrial dysplasia and glandular hyperplasia, in addition to a statistically significant (P<0.0001) elevation in gland-associated TGFbeta1 protein.

Aged↗
PubMed2000

Effects of a novel non-carboxylic thromboxane A2 receptor antagonist (BM-531) derived from torasemide on platelet function.

In this study we examined the thromboxane A(2)(TXA(2)) receptor antagonist property of BM-531 (N-tert -butyl- N'-[(2-cyclohexylamino-5-nitrobenzene)sulfonyl]urea), a torasemide derivative, on platelet function. The drug affinity for human washed platelet TXA(2)receptors labelled with [(3)H]SQ-29,548 has been determined (IC50: 0.0078 microM) and demonstrated to be higher than sulotroban (IC50: 0.93 microM) and SQ-29,548 (IC50: 0.021 microM). The antiaggregatory potency has been confirmed since we demonstrated that BM-531 prevented platelet aggregation in human citrated platelet-rich plasma induced by arachidonic acid (600 microM) (ED100: 0.125 microM), U-46619, a stable TXA(2)agonist (1 microM) (ED50: 0.482 microM) and collagen (1 microg mL(-1)) (% of inhibition: 42.9% at 10 microM) and inhibited the second wave of ADP (2 microM). Moreover, when BM-531 was incubated in whole blood from healthy donors, the closure time measured by the recently developed platelet function analyser (PFA-100(trade mark)) was significantly prolonged. These results suggest that BM-531 can be regarded as a novel non-carboxylic TXA(2)antagonist with a powerful antiplatelet potency.

Adenosine Diphosphate↗
PubMed2000

Guidelines for monitoring patients taking tamoxifen treatment.

Tamoxifen is the most important anti-breast cancer drug in clinical use and has the potential to be used as a chemopreventive breast cancer agent. Using outpatient hysteroscopy and based on 2 case control and 2 cohort follow-up studies in our department, we were able to demonstrate that 50% of women receiving long term tamoxifen experienced some sort of adverse endometrial effects. Although many women retain an atrophic endometrial layer, tamoxifen intake can lead to extensive senile cystic atrophia of the human endometrium, to endometrial hyperplasia and to endometrial polyp formation. Based on a critical review of the literature, we have shown that tamoxifen doubles the risk for developing endometrial cancer in postmenopausal women, although this increased risk may be higher and is duration (i.e. time of use)-dependent. Screening patients with breast cancer for endometrial abnormalities while they are taking tamoxifen is feasible and uterine morbidity related to tamoxifen intake is preventable. Although screening may increase drug compliance it may not be cost-beneficial. However, uterine safety becomes important when only a small benefit of the treatment is to be expected as in the use of tamoxifen in healthy women for breast cancer prevention. The aim of this report is to discuss methods and guidelines for detecting endometrial adverse effects of tamoxifen and to provide the clinician with a current opinion on timing and frequency of screening patients taking tamoxifen for the development of endometrial cancer. In summary, those who advocate screening should start with pretreatment uterine assessment using transvaginal ultrasonography or outpatient hysteroscopy. Symptom-free women with a normal pretreatment uterine cavity can be screened annually with transvaginal sonography from 2 to 3 years after the start of tamoxifen. Hysteroscopy or saline infusion sonography will be required if there is endometrial thickening because the only value of transvaginal ultrasonography is a normal finding being a thin rectilinear endometrium.

Endometrium↗
PubMed1999

Lack of evidence from HPLC 32P-post-labelling for tamoxifen-DNA adducts in the human endometrium.

Tamoxifen is associated with an increased incidence of endometrial cancer in women. It is also a potent carcinogen in rat liver and forms covalent DNA adducts in this tissue. A previous study exploring DNA adducts in human endometria, utilizing thin layer chromatography 32P-postlabelling, found no evidence for adducts in tamoxifen-treated women [Carmichael,P.L., Ugwumadu,A.H.N., Neven,P., Hewer,A.J., Poon,G.K. and Phillips,D.H. (1996) Cancer Res., 56, 1475-1479]. However, subsequent work utilizing HPLC 32P-post-labelling [Hemminki,K., Ranjaniemi,H., Lindahl,B. and Moberger,B. (1996) Cancer Res., 56, 4374-4377] suggested that very low levels could be detected. We have sought to investigate this question further by reproducing the HPLC methodology at two centres, and analysing endometrial DNA from 20 patients treated with 20 mg/day tamoxifen for between 22 and 65 months. Liver DNA isolated from tamoxifen-treated rats was used as a positive control. We found no convincing evidence for tamoxifen-derived DNA adducts in human endometrium. HPLC elution profiles of post-labelled DNA from tamoxifen-treated women were indistinguishable from those obtained with DNA from 14 untreated women and from six women taking toremifene, an analogue of tamoxifen.

Aged↗
PubMed1998

Genomic changes in endometrial polyps associated with tamoxifen show no evidence for its action as an external carcinogen.

Eighty-eight endometrial specimens from 36 postmenopausal breast cancer patients treated with tamoxifen were investigated cytogenetically and molecularly using fluorescence in situ hybridization with appropriate probes for the HMGIC and HMGIY genes. Twenty control specimens, 10 endometrial polyps, and 10 endometrial biopsy specimens were investigated in the same way. Of the 88 specimens, 44 were from endometrial polyps; 3 were from endocervical polyps; 7 were from cystic endometrium; 30 were from normal or atrophic endometrium, normal endocervix, or myometrium; and 4 were from endometrial carcinomas. Chromosome investigation of the endometrial polyps showed the nature of the chromosome changes in tamoxifen-induced polyps to be the same as that in the controls and in sporadic endometrial polyps described in the literature. HMGIC and HMGIY gene rearrangements in both groups were identical as shown by fluorescence in situ hybridization, which also allowed for the detection of seven hidden paracentric inversions involving 12q15, one of which occurred in a cystic endometrium. The carcinomas did not exhibit any of these changes. Because abnormal expression of HMGIC or HMGIY as a consequence of structural chromosome changes in 12q15 or 6p21, respectively, is invariably associated with benign neoplasia, tamoxifen-associated endometrial polyps are unlikely to undergo further malignant transformation, and a mode of action of tamoxifen as an external carcinogen is unlikely.

Antineoplastic Agents, Hormonal↗