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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Anti-estrogens and progestagens are synergistically active in the treatment of hormone dependent tumors. The combined action of both compounds in daily treatment schedules are analyzed in rat uterus and in DMBA- induced rat mammary tumors. Tamoxifen in contrast to estradiol does not significantly affect tissue growth, while PgR induction is considerably stimulated by Tamoxifen. It is suggested that the "estrogenic effects" of Tamoxifen and estradiol are separately modulated. When given in sequential combination with anti-estrogens, the anti-tumor response of progestagens is enhanced. Combinations of hormonal treatment based on careful analysis of the regulation processes at target cell level may greatly improve results of anti-tumor therapy.
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PMID:Independent regulation of growth and steroid receptors in uterus and mammary tumors of rats. 623 Sep 84

Methods and evaluation of the human tumor stem cell assay (HTSCA) are described. Advantages and disadvantages of the test system are elaborated. The in vitro/in vivo correlation in the drug screening of human ovarian carcinomas shows that the prediction of sensitivity to a cytotoxic agent is only possible in 64%. Prediction of drug resistance, however, seems to be possible in 95%. The number of patients that profit from the HTSCA seems to be only less than 10%. Our investigations describe the influence of various hormones and antiestrogens on the colony formation of human ovarian carcinoma cells. Tamoxifen and his major metabolite 4-hydroxy-tamoxifen were the most active agents. Both compounds inhibit the colony survival (70% at pharmacological concentrations) of 60% of the screened ovarian carcinomas. A significant correlation to the quantitative level of estrogen or progesterone receptors could not be proved. Colony formation of ovarian carcinoma cells was compared in the HTSCA as described by Hamburger and Salmon and in a methylcellulose-monolayer system. Our results show that the colony formation corresponds to the results of the original HTSCA: Cloning ovarian carcinoma cells in the methylcellulose-monolayer, however, seems to be technically easier and faster.
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PMID:[Significance of the colony formation test in ovarian carcinoma]. 623 68

After ovariectomy DMBA tumor-bearing SD rats were treated with the estrogen DES, a combination of DES plus mammary tumor-inhibiting antiestrogen (tetramethylHES, 3,3'HES and tamoxifen respectively) or with tetramethylHES alone. Small doses of DES led to a stimulation of tumor growth showing a maximum effect at 1 microgram/kg/day, whereas higher doses inhibited tumor growth. In the combination experiment only tetramethylHES reduced, i.e. antagonized, the DES effect. Tamoxifen and 3,3'HES, however, led to an increase of the tumor growth-stimulating and inhibiting effects of DES. Only the dose of 10 mg/kg/day of tetramethylHES led to a slight stimulation of the tumor growth in ovariectomized DMBA tumor-bearing rats. These results indicate that 3,3'HES and tamoxifen possibly unfold their mammary tumor-inhibiting activity by means of their estrogenic potency, whereas tetramethylHES might act as an antiestrogen, though the latter compound does not lack estrogenic activity completely.
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PMID:Tumor growth-stimulating and inhibiting effects of antiestrogens on the DMBA-induced mammary carcinoma of the ovariectomized, diethylstilbestrol-treated SD rat. A study on the mechanism of action of antiestrogens. 630 29

Clinical results of tamoxifen ('Nolvadex'-ICI) monotherapy in 44 premenopausal women with advanced breast cancer have been reviewed. Objective tumor regression was achieved in 12 (27%) patients and a further 10 (22%) were classified as 'stabilized'. Median duration of response was 12.7 months at the time of analysis. Greatest benefits occurred in soft tissue dominant and receptor-positive tumors, but there was no correlation between tumor response and other clinical manifestations of estrogen deprivation (e.g. menstrual disturbance, hot flushes). The benefits of conventional doses of tamoxifen do not therefore appear to be influenced by menopausal status and compare favorably to achievements reported after surgical oophorectomy.
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PMID:Tamoxifen (Nolvadex) for premenopausal patients with advanced breast cancer. 636 11

The cumulative effects of Lentinan and endocrine therapy on the growth of DMBA (7, 12-dimethyl benzanthracene)-induced mammary tumors of rats were studied. Multiple injection of Lentinan alone resulted in a slight degree of regression of the tumor growth, when administered to rats bearing mammary tumors of about 1 cm in size. Ovariectomy-adrenalectomy, ovariectomy, and adrenalectomy, which are performed as surgical endocrine therapy, resulted in a more marked regression of the tumor than that produced by Lentinan treatment alone. Furthermore, multiple injection of Lentinan performed on these mammary tumor-bearing rats which had received surgical endocrine therapy 2 weeks previously evoked a marked regression of tumor growth. However, no changes in growth curves and survival rates, compared with those of saline controls were observed, indicating that Lentinan might be a useful agent when combined with surgical endocrine therapy. Concurrent injection of Lentinan resulted in a slight augmentation, although the histamine sensitivity of tumor bearing rats which had previously received surgical endocrine therapy elevated greatly, compared with that of controls. By contrast administration of Tamoxifen, which is used for medical endocrine therapy, resulted in a lesser degree of regression than that observed following surgical endocrine therapy, and was also not greatly affected by Lentinan injection.
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PMID:[Cumulative effects of lentinan and endocrine therapy on the growth of DMBA-induced mammary tumor in rats]. 643 Feb 43

Patients with advanced prostatic carcinoma who had received minimal or no prior therapy were treated with tamoxifen citrate in escalating doses from 10 to 50 mg orally twice a day. Twenty-nine courses were evaluated in 17 patients. Entry was limited to patients with measurable sites of disease. There were no objective responses at any dose level in these measurable sites. Acid and alkaline phosphatase were reduced in 0% and 18% of courses, respectively. Serum testosterone increased by an average of 119 ng/ml. Most increases were transient; no tumor flares were observed. Transperineal prostate biopsies in selected patients after completion of treatment showed no evidence of tumor necrosis or alteration in histologic grade of the tumors. Tamoxifen citrate, over the range of doses evaluated, has no activity in metastatic prostatic carcinoma.
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PMID:Tamoxifen in advanced prostatic carcinoma. A dose escalation study. 643 May 41

The efficacy of tamoxifen treatment was studied in 46 postmenopausal patients with localized and disseminated breast cancer. Objective remissions were observed in 47.8, stabilization of tumor process-in 21.7%, mostly in cases of metastasis into the skin, subcutaneous fat, lymph nodes, pleura and bones. Tamoxifen proved sufficiently effective both in primary treatment and as a measure taken when the effect of a specific therapy (radiation, cytostatic or hormonal) was over. Side-effects were slight and were registered in 19.6%.
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PMID:[Use of tamoxifen in patients with disseminated and local breast neoplasms]. 649 91

It is known from previous investigations by other authors that the non-steroidal molecule Tamoxifen competes for estradiol binding sites in target tissues and displays partial agonist-antagonist effects. It is able to bind a cytosol protein distinct from ER which has been detected in target tissues, as well as in fetal target and non-target organs. The present work investigates the antiestrogen binding activity of human breast cancer cell lines and tumor biopsies. It is found that BT-20 and MDA-MB 231 cell lines devoid of ER and PGR contain a cytosol protein component able to bind antiestrogens with a high affinity (= 2 X 10(-9) M). The 3H-labeled complex prepared in hypotonic buffer sediments at 6.25 S in a sucrose gradient. A substantial amount of antiestrogen binding sites is found to be linked to the microsomal cell fraction, in agreement with previous data from other investigators. In experiments using whole cells incubated at 37 C, the complex is depleted from the cytosol compartment. A low amount of radioactivity is extracted from the purified nuclei. In the cytosol of human breast tumor biopsies the presence of antiestrogen binding sites is not exclusively associated with the presence of ER and PGR. The identity of the natural ligand which binds to these sites under physiological conditions merits investigation.
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PMID:High affinity cytosol binding site(s) for antiestrogens in two human breast cancer cell lines and in biopsy specimens devoid of estrogen receptors. 652 39

The effect of tamoxifen on the growth of malignant melanoma was investigated using human cell lines and single-cell suspensions prepared from patients' tumours cultured in soft agar. Tamoxifen stimulated both [3H]-thymidine incorporation and cell numbers in all of the cell lines tested. Cytoplasmic oestrogen receptor (ER) was detected in one of the responding lines and progesterone receptor (PR) in another. Tumour colony formation in soft agar culture was satisfactorily established from tumour cell suspensions from 13 of 21 patients, only one of which had detectable cytoplasmic ER. Greater than 50% reduction in colony formation with 5 X 10(-7) M tamoxifen occurred in two tumours, neither of which contained ER. These results indicate that tamoxifen has the potential to either retard or accelerate the growth of human malignant melanoma.
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PMID:The effect of tamoxifen on the growth of human malignant melanoma in vitro. 654 Jan 81

Human pituitary tumors were studied in vitro using the clonogenic stem cell assay. Mechanical dispersion was used to prepare single cell suspensions for plating. Colony formation occurred in 21 of 24 tumors plated. Bromocriptine (Brc; 10 nM) added to the medium resulted in a significant decrease in the number of colonies formed in 5 of 10 prolactinomas and in 1 tumor secreting both PRL and GH. However, PRL secretion was decreased in 8 of 9 tumors tested. Brc had no effect on either colony formation or hormone secretion in other tumors secreting GH (n = 2), ACTH (n = 2), or FSH (n = 1) or in nonsecreting tumors (n = 4). Tamoxifen (Tam; 10(-7) M) inhibited colony formation in 6 of 10 prolactinomas and in 1 tumor secreting GH and PRL. PRL secretion into the medium correlated with the changes in the number of colonies. Tam was not effective in any other tumor tested. In only 1 instance was there a synergistic action between Brc and Tam on inhibition of colony formation. Brc, but not Tam, caused a significant decrease in the size of the colonies formed from cells of PRL-secreting tumors. The least numbers of colonies per plate were found in 3 prolactinomas from patients treated preoperatively with Brc. We conclude that the soft agar clonogenic assay technique is a feasible method to study human pituitary tumors in vitro. Both Brc and Tam inhibited colony formation in this system in a significant proportion of tumors. The potential antiproliferative action of Tam in vivo needs to be studied in view of these results.
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PMID:Inhibitory action of bromocriptine and tamoxifen on the growth of human pituitary tumors in soft agar. 661 72


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