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Thread: Nolvadex~Tamoxifen Citrate

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    Default Nolvadex~Tamoxifen Citrate



    Nolvadex

    (Tamoxifen Citrate)

    Tamoxifen is an antagonist of the estrogen receptor in breast tissue. It has been the standard endocrine (anti-estrogen) therapy for hormone-positive early breast cancer, although aromatase inhibitors have been proposed for postmenopausal women.
    Some breast cancer cells require estrogen to grow. Estrogen binds to and activates the estrogen receptor in these cells. Tamoxifen is metabolized into compounds that also bind to the estrogen receptor but do not activate it. Furthermore tamoxifen prevents estrogen from binding to its receptor. Hence breast cancer cell growth is blocked.Tamoxifen is a SERM.

    Selective Estrogen Receptor Modulators (SERMs) are a class of compounds that act on the estrogen receptor. A characteristic that distinguishes these substances from pure receptor agonists and antagonists is that their action is different in various tissues, thereby granting the possibility to selectively inhibit or stimulate estrogen-like action in various tissues.

    Nolvadex essentially blocks the action of estrogen in certain tissues like breast tissue. This is advantageous to the male bodybuilder because Tamoxifen is an effective way to prevent gynocomastia. A daily dose of 20mg will typically protect a male from gyno. I always like to keep a bottle of Tamoxifen on hand for emergency gyno treatment as it is one of the fastest ways to mitigate gyno syptoms.

    In addition to blocking the action of estrogen, Tamoxifen also increases testosterone, LH and FSH and estrogen. Estrogen is of course blocked in certain tissues leaving a circulating amount that may be beneficial to lipids. Higher circulating estrogen may produce a puffy or watery look so an aromatase inhibitor would be more suited for controlling estrogen and reducing bloat. Unfortunately there is some evidence that Tamoxifen reduces IGF-1 levels so it may not be the best choice for PCT when used alone. Post cycle is a fragile time so lower IGF-1 levels are not desirable along with the higher circulating estrogen. I personally would use a low dose aromatase inhibitor alongside Tamoxifen if employing it for PCT.

    ~heavyiron~
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    Tamoxifen treatment in oligozoospermia.

    Bartsch G, Scheiber K.

    This study of the effects of long-term tamoxifen administration on semen analysis of oligospermic males confirms the potential therapeutic efficacy in normogonadotrophic oligospermia. 38 out of the 56 patients responded well to long-term treatment with 30 mg tamoxifen daily. According to the nomenclature of Eliasson, 32 patients reached normal sperm density and 16 patients normal sperm motility after tamoxifen treatment. In the group of responders a pregnancy rate of 34% is obtained. As far as the endocrinological parameters are concerned normogonadotrophic patients (responders and non-responders) showed an increase in testosterone, 17beta-estradiol, LH and FSH levels, whereas the levels of prolactin and testosterone/estradiol-binding globulin remained unchanged. No alterations at all were seen with regard to semen volume, during the time of tamoxifen treatment.

    PMID: 7250160 [PubMed - indexed for MEDLINE]
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    Stimulation of calcitonin secretory capacity by increased serum levels of testosterone in men treated with tamoxifen.

    Schopman W, Slager E, Hackeng WH, Mulder H.
    Department of Internal Medicine, Eudokia Hospital, Bergsingel, Rotterdam, The Netherlands.

    Previous studies have suggested that sex steroids, including both oestrogen and testosterone, influence calcitonin secretion. However, a negative effect of gonadotrophins on calcitonin has not been excluded. Twelve men with infertility and low-normal serum levels of testosterone were studied before and during tamoxifen therapy. Increases in the serum levels of LH, FSH, testosterone and calcitonin were observed after treatment. Our findings suggest that testosterone has a direct influence on calcitonin secretion.

    PMID: 3123401 [PubMed - indexed for MEDLINE]
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    Hormonal effects of an antiestrogen, tamoxifen, in normal and oligospermic men.

    Vermeulen A, Comhaire F.

    The administration of tamoxifen, 20 mg/day for 10 days, to normal males produced a moderate increase in luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone, and estradiol levels, comparable to the effect of 150 mg of clomiphene citrate (Clomid). However, whereas Clomid produced a decrease in the LH response to LH-releasing hormone (LHRH), no such effect was seen after the administration of tamoxifen. In fact, prolonged treatment (6 weeks) with tamoxifen significantly increased the LH response to LHRL. Treatment of patients with "idiopathic" oligospermia for 6 to 9 months resulted in a significant increase in gonadotropin, testosterone, and estradiol levels. A significant increase in sperm density was observed only in subjects with oligospermia below 20 X 10(6)/ml and normal basal FSH levels. When basal FSH levels were increased or oligospermia was moderate (greater than 20 X 10(6)/ml); no effect on sperm density was seen. As sperm density increased, FSH levels decreased, suggesting an inhibin effect. Sperm motility was not improved by tamoxifen treatment. In five boys with delayed puberty, tamoxifen treatment appeared to activate the pituitary-gonadal axis and pubertal development.

    PMID: 640052 [PubMed - indexed for MEDLINE]
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    Hormonal changes in tamoxifen treated men with idiopathic oligozoospermia.

    Hampl R, Heresová J, Lachman M, Sulcová J, Stárka L.
    Research Institute of Endocrinology, Prague/Czechoslovakia.

    Three months of tamoxifen treatment of 43 men with idiopathic oligozoospermia, out of which 20 completed the study, resulted in a significant enhancement of sperm motility, but the improvement of sperm parameters was in no relation to the FSH response to short time tamoxifen treatment. There was a significant increase of testosterone, estradiol, LH, FSH, SHBG, 17 alpha-hydroxy-progesterone and also of 11 beta-hydroxyandrostenedione, an androgen of exclusively adrenal origin, during the treatment and (with the exception of the latter), on the first week after discontinuation of the therapy. Significantly elevated testosterone and SHBG concentrations were retained still 9 weeks after finishing of the therapy. The results confirm that tamoxifen treatment provides conditions more favourable for conception and demonstrate that also adrenal steroidogenesis is positively influenced by this antiestrogen.

    PMID: 3243340 [PubMed - indexed for MEDLINE]
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    Effect of tamoxifen on GH and IGF-1 serum level in stage I-II breast cancer patients.

    Mandalà M, Moro C, Ferretti G, Calabro MG, Nolè F, Rocca A, Munzone E, Castro A, Curigliano G.

    Division of Medical Oncology, European Institute of Oncology, Via Ripamonti 435, 20141-Milan, Italy. mario.mandala@ieo.it

    OBJECTIVE: Tamoxifen suppresses insulin-like growth factor-1 (IGF-1) plasma levels in early and advanced breast cancer patients. Relationships between tamoxifen (GH) and IGF-1 are complex and not completely described yet. The present investigation was performed to evaluate the effect of acute and chronic tamoxifen administration on GH response to growth hormone-releasing hormone (GHRH), as well as on IGF-1 serum levels. MATERIALS AND METHODS: Evaluation of GH after administration of GHRH was performed (a) at baseline, (b) 3 hours after 20 mg oral administration of tamoxifen and (c) after 12 weeks of 20 mg a day oral tamoxifen treatment, in fifteen postmenopausal stage I-II breast cancer patients. IGF-I was measured at baseline and after chronic tamoxifen administration. RESULTS: The GH response to GHRH was significantly reduced after 12 weeks of tamoxifen 10 mg administered twice a day orally (mean peak 3.2 +/- 0.2 micrograms/l, mean AUC 261.3 +/- 18.2 micrograms/minute p < 0.01 versus basal AUC). A concomitant significant reduction of IGF-1 was observed after 3 months of tamoxifen treatment. Basal pretreatment levels of 113.2 +/- 15.5 micrograms/l were suppressed to 70 +/- 7.9 micrograms/l (p < 0.01). CONCLUSION: Our study confirm the inhibitory effect of tamoxifen on IGF-I and suggested, as shown in previous in vitro data, that its suppression could be directly related to GH reduction in response to GHRH stimulation
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    Tamoxifen, serum lipoproteins and cardiovascular risk.

    Bruning PF, Bonfrer JM, Hart AA, de Jong-Bakker M, Linders D, van Loon J, Nooyen WJ.
    Department of Clinical Oncology, The Netherlands Cancer Institute, Amsterdam.

    The influence of tamoxifen on plasma lipids and lipoproteins was monitored in 46 postmenopausal and 8 premenopausal women treated for advanced breast cancer up till 6 months. Total cholesterol (total-C) did not significantly change. However, high density lipoprotein cholesterol (HDL-C) and the HDL-C/total-C ratio rose significantly. Low density lipoprotein cholesterol was significantly decreased. Triglycerides and free fatty acids did not change markedly. The concomitant rise of sex hormone binding globulin and thyroxine binding globulin indicates that the increase of HDL-C with prolonged use of tamoxifen is compatible with an intrinsic oestrogenic effect of tamoxifen on the liver. The increased HDL-C/total-C ratio lends no support to the concern that long-term administration of this anti-oestrogenic drug might lead to an increased cardiovascular risk.

    PMID: 3207604 [PubMed - indexed for MEDLINE]
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    Effects of Tamoxifen and Exemestane on Cognitive Functioning of Postmenopausal Patients With Breast Cancer: Results From the Neuropsychological Side Study of the Tamoxifen and Exemestane Adjuvant Multinational Trial

    Christina M. Schilder, Caroline Seynaeve, Louk V. Beex, Willem Boogerd, Sabine C. Linn, Chad M. Gundy, Hilde M. Huizenga, Johan W. Nortier, Cornelis J. van de Velde, Frits S. van Dam, and Sanne B. Schagen*
    From the Departments of Psychosocial Research and Epidemiology, Neuro-oncology, and Medical Oncology, Netherlands Cancer Institute; Department of Neurology, Slotervaart Medical Center; Department of Psychology, University of Amsterdam, Amsterdam; Department of Medical Oncology, Erasmus Medical Center-Daniel den Hoed Cancer Center, Rotterdam; Department of Medical Oncology, Radboud University Medical Center, Nijmegen; and the Departments of Medical Oncology and Surgical Oncology, Leiden University Medical Center, the Netherlands.


    * To whom correspondence should be addressed. E-mail: s.schagen@nki.nl


    Purpose: To evaluate the influence of adjuvant tamoxifen and exemestane on cognitive functioning in postmenopausal patients with breast cancer (BC).

    Patients and Methods: Neuropsychological assessments were performed before the start (T1) and after 1 year of adjuvant endocrine treatment (T2) in Dutch postmenopausal patients with BC, who did not receive chemotherapy. Patients participated in the international Tamoxifen and Exemestane Adjuvant Multinational trial, a prospective randomized study investigating tamoxifen versus exemestane as adjuvant therapy for hormone-sensitive BC.

    Results: Participants included 80 tamoxifen users (mean age, 68.7 years; range 51 to 84), 99 exemestane users (mean age, 68.3 years; range, 50 to 82), and 120 healthy controls (mean age, 66.2 years; range, 49 to 86). At T2, after adjustment for T1 performance, exemestane users did not perform statistically significantly worse than healthy controls on any cognitive domain. In contrast, tamoxifen users performed statistically significantly worse than healthy controls on verbal memory (P < .01; Cohen's d = .43) and executive functioning (P = .01; Cohen's d = .40), and statistically significantly worse than exemestane users on information processing speed (P = .02; Cohen's d = .36). With respect to visual memory, working memory, verbal fluency, reaction speed, and motor speed, no significant differences between the three groups were found.

    Conclusion: After 1 year of adjuvant therapy, tamoxifen use is associated with statistically significant lower functioning in verbal memory and executive functioning, whereas exemestane use is not associated with statistically significant lower cognitive functioning in postmenopausal patients with BC. Our results accentuate the need to include assessments of cognitive effects of adjuvant endocrine treatment in long-term safety studies.
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    J Clin Endocrinol Metab. 2010 Sep 15. [Epub ahead of print]

    Neuroendocrine Regulation of Growth Hormone and Androgen Axes by Selective Estrogen Receptor Modulators in Healthy Men.

    Birzniece V, Sata A, Sutanto S, Ho KK.
    Garvan Institute of Medical Research and Department of Endocrinology (V.B., A.S., S.S., K.K.Y.H.), St. Vincent's Hospital, Sydney, New South Wales 2010, Australia; and The University of New South Wales (V.B., K.K.Y.H.), Sydney, New South Wales 2052, Australia.

    Abstract

    Context: In men, the stimulation of GH and inhibition of LH secretion by testosterone requires aromatization to estradiol. Tamoxifen, a selective estrogen receptor modulator (SERM), possesses central estrogen antagonistic effect but peripheral hepatic agonist effect, lowering IGF-I. Thus, tamoxifen is likely to perturb the neuroendocrine regulation of GH and gonadal axes. Raloxifene, a SERM, is used for therapy of osteoporosis in both sexes. Its neuroendocrine effects in men are poorly understood. Objective: The aim was to compare the impact of raloxifene and tamoxifen on GH-IGF-I and gonadal axes in healthy men. Design: We conducted a randomized, open-label crossover study. Patients and Intervention: Ten healthy men were randomized to 2-wk sequential treatment with tamoxifen (10 and 20 mg/d) and raloxifene (60 and 120 mg/d), with a 2-wk intervening washout period. Main Outcome Measures: We measured the GH response to arginine and circulating levels of IGF-I, LH, FSH, testosterone, and SHBG. Results: Tamoxifen, but not raloxifene, significantly reduced IGF-I levels by 25 ± 6% (P < 0.01) and increased SHBG levels by 20 ± 7% (P < 0.05) at the higher therapeutic dose. There was a nonstatistically significant trend toward a reduction in the GH response to arginine with both SERMs. Both drugs significantly increased LH, FSH, and testosterone concentrations. The mean increase in testosterone (40 vs. 25%; P < 0.05) and LH (70 vs. 30%; P < 0.01) was significantly greater with tamoxifen than with raloxifene treatment. Conclusions: Tamoxifen, but not raloxifene, reduces IGF-I levels. Both SERMs stimulate the gonadal axis, with tamoxifen imparting a greater effect. We conclude that in therapeutic doses, raloxifene perturbs the GH and gonadal axes to a lesser degree than tamoxifen.

    PMID: 20843951 [PubMed - as supplied by publisher]
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    Urol Int. 2009;83(4):446-51. Epub 2009 Dec 8.

    Role of testosterone/estradiol ratio in predicting the efficacy of tamoxifen citrate treatment in idiopathic oligoasthenoteratozoospermic men.

    Cakan M, Aldemir M, Topcuoglu M, Altuğ U.
    Department of 2nd Urology, SB Ankara Dişkapi Training Hospital, Ankara, Turkey. muratcakandr@yahoo.com

    Abstract

    AIM: It was the aim of this study to investigate the effect of a low testosterone/estradiol (T/E2) ratio and the normalization of this ratio by an aromatase inhibitor, anastrozole, on the treatment results of tamoxifen citrate (TAM) in idiopathic oligoasthenoteratozoospermic patients with a normal T/E2 ratio.
    PATIENTS AND METHODS: 127 normogonadotropic men were included in this study. TAM (10 mg twice daily) was applied to 103 of the patients (group 1). The control group consisted of 25 patients who did not receive any treatment (group 2). After 3 months, TAM therapy was continued in 42 of the patients with a normal T/E2 ratio (group 1A). Of the remaining 61 patients with low ratios, 30 continued with TAM (group 1BTAM), while the remaining 31 patients underwent additional anastrozole therapy (1 mg/day) to TAM (group 1BANA).
    RESULTS: In the 3rd month of the study, while the sperm concentration and motility were found significantly improved in group 1 (p < 0.05), they were significantly lower in groups 1BTAM and 1BANA than in group 1A (p < 0.01). In the 6th month of the study, the mean T/E2 ratio was normal in group 1A and group 1BANA, but was lower than normal ranges in group 1BTAM. The sperm concentration and motility significantly increased in groups 1A and 1BANA (p < 0.05).
    CONCLUSIONS: A significant decrease in the T/E2 ratio was seen in the majority of the patients during TAM treatment. Normalization of this ratio by addition of anastrozole to the treatment regimen improved the treatment outcomes. However, a placebo-controlled study is needed to confirm our results.

    PMID: 19996653 [PubMed - indexed for MEDLINE]
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    Andrologia. 1985 Jul-Aug;17(4):369-78.

    Effect of lower versus higher doses of tamoxifen on pituitary-gonadal function and sperm indices in oligozoospermic men.

    Dony JM, Smals AG, Rolland R, Fauser BC, Thomas CM.

    Abstract

    Administration of the antiestrogen tamoxifen for one month to 12 patients with idiopathic oligozoospermia significantly increased the mean basal testosterone (T) level and the responses of luteinizing hormone (LH) and follicle stimulating hormone (FSH) to constant luteinizing hormone releasing hormone (LHRH) infusion but did not significantly influence the mean oestradiol (E2) levels or the E2 over testosterone ratio. Mean sperm concentration and total sperm output increased by about 70% after a mean treatment period of 5.5 +/- 0.4 months. No statistically significant difference was found between the two subgroups of patients treated with either the lower (5 or 10 mg once daily) or higher dose of tamoxifen (10 mg twice daily) with respect to basal or LHRH stimulated gonadotropin and testosterone response or the E2/T ratio and the effect on sperm density and total sperm output. In both subgroups the sperm motility and morphology remained unchanged. In conclusion higher doses of tamoxifen in this study prove not to be superior to lower doses in improving mean sperm density and total sperm output. The relative small percentage of patients achieving normalisation of only these sperm parameters pleads for further search for more effective selection of patients and other more effective treatment modalities in patients with idiopathic oligozoospermia.


    PMID: 3931502 [PubMed - indexed for MEDLINE]
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    Treatment of gynecomastia with tamoxifen: A double-blind crossover study

    Lawrence N. Parker a, b, c, , David R. Gray b, c, a, Michael K. Lai b, c, a and Ellis R. Levin b, c, a

    a Medicine, Service, University of California at Irvine, USA
    b Pharmacy Service, University of California at Irvine, USA
    c Long Beach Medical Program, Veterans Administration Medical Center, Long Beach, Calif., USA

    Abstract

    Benign asymptomatic or painful enlargement of the male breast is a common problem, postulated to be due to an increased estrogen/testosterone ratio or due to increased estrogenic or decreased androgenic stimulation via estrogen or androgen receptor interactions. Treatment at present consists of analgesic medication or surgery. However, treatment directed against the preponderance of estrogenic stimulation would seem to represent a more specific form of therapy. In the present double-blind crossover study, one-month courses of a placebo or the antiestrogen tamoxifen (10 mg given orally bid) were compared in random order. Seven of ten patients experienced a decrease in the size of their gynecomastia due to tamoxifen (P < 0.005). Overall, the decrease for gynecomastia for the whole group was significant (P < 0.01). There was no beneficial effect of placebo (P > 0.1). Additionally, all four patients with painful gynecomastia experienced symptomatic relief. There was no toxicity. The reduction of breast size was partial and may indicate the need for a longer course of therapy. A followup examination was performed in eight out of ten patients nine months to one year after discontinuing placebo and tamoxifen. There were no significant changes from the end of the initial study period except for one tamoxifen responder who developed a recurrence of breast tenderness after six months, and one nonresponder who demonstrated an increase in breast size and a new onset of tenderness after ten months. Therefore, antiestrogenic treatment with tamoxifen may represent a safe and effective mode of treatment for selected cases of cosmetically disturbing or painful gynecomastia.
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    [Influence of size and duration of gynecomastia on its response to treatment with tamoxifen]

    [Article in Spanish]
    Devoto C E, Madariaga A M, Lioi C X, Mardones N.
    Sección Endocrinología, Servicio de Medicina, Hospital Clínico San Borja Arriarán, Santiago, Chile. edevoto@vtr.net

    Abstract

    BACKGROUND: Gynecomastia is treated when it is painful, there are psychosocial repercussions or it does not revert in less than two years. It is treated with the antiestrogenic drug tamoxifen, but there are doubts about its effectiveness in high volume gynecomastias or in those lasting more than two years.

    AIM: To assess the effectiveness and safety of tamoxifen for gynecomastia and the influence of its volume and duration on the response to treatment.

    PATIENTS AND METHODS: Forty three patients with gynecomastia, aged 12 to 62 years, were studied. Twenty seven patients had a pubertal physiological gynecomastia, in eight it was caused by medications, in four it was secondary to hypogonadism, in three it was idiopathic and in one it was due to toxic exposure. Twenty patients had mastodynia and in 33, gynecomastia had a diameter over 4 cm. It lasted less than two years in 30 patients, more than two years in nine and four did not recall its duration. All were treated with tamoxifen 20 mg/day for 6 months. A follow up evaluation was performed at three and six months of treatment.

    RESULTS: Mastodynia disappeared in all patients at three months. At six months gynecomastia disappeared in 26 patients (62%), but relapsed in 27%. All gynecomastias caused by drugs with antiandrogen activity disappeared. Fifty two percent of gynecomastias over 4 cm and 90% of those of less than 4 cm in diameter disappeared (p<0.05). Fifty six percent of gynecomastias lasting more than two years and 70% of those of a shorter duration disappeared (p=NS). Two patients had diarrhea or flushes associated to the therapy.

    CONCLUSIONS: Tamoxifen is safe and effective for the treatment of gynecomastia. Larger lesions have a lower response to treatment.
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    Quote Originally Posted by heavyiron View Post
    Conclusion: After 1 year of adjuvant therapy, tamoxifen use is associated with statistically significant lower functioning in verbal memory and executive functioning[/INDENT]
    Fucking hell.

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    my swelling has gone down a little I am also coming off my cycle I used nolvadex throughout and coming off should the swelling decrease

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    Default Inability To Metabolize Tamoxifen

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    medicalnewstoday.com/articles/254491.php


    Breast cancer patients with a certain genetic liver enzyme alteration do not respond well to the hormone therapy tamoxifen as they have difficulty metabolizing the drug, leading to an increased risk of death and recurrence.


    The finding comes from a study carried out by researchers from the Mayo Clinic Cancer Center and the Austrian Breast and Colorectal Cancer Study Group, and was published in the journal Clinical Cancer Research


    They identified that women with alterations of the liver enzyme CYP2D6 can't metabolize the drug as well as those with normal enzyme activity, which can lead to severe complications.


    Lead author of the study, Matthew Goetz, M.D., said, "Our findings confirm that, in early breast cancer treated with tamoxifen, genetic alterations in CYP2D6 lead to a higher likelihood of recurrence and death."


    The study involved monitoring the recurrence of cancer and death among two groups of women who received different forms of breast cancer treatment. The first group included postmenopausal women with primary estrogen receptor-positive breast cancer who solely received tamoxifen therapy for five years, while the second group of women took tamoxifen for two years and then proceeded to take an aromatase inhibitor (which does not require the CYP2D6 enzyme) called anastrozole for three years.


    They found that women who had significant genetic alterations of CYP2D6 were 2.5 times more likely to develop the cancer again or die compared to women with normal CYP2D6 activity. The recurrence of the cancer and death was 1.7 times greater among women with intermediate levels of the enzyme.


    Surprisingly, the women who had genetic alterations of the enzyme but switched treatment after two years (from tamoxifen to anastrozole) did not have a greater risk of recurrence or death.



    Senior author James Ingle, M.D., of Mayo Clinic, said:


    "Switching from tamoxifen to an aromatase inhibitor may be one reason for the discrepant studies surrounding CYP2D6 and tamoxifen -- as information about whether a patient took an aromatase inhibitor after tamoxifen was not available in most of the prior studies."



    Around 6 percent of women in Europe and the U.S. have a genetic liver enzyme alteration which makes them unable to properly metabolize the drug tamoxifen. Blood tests are able to identify genetic variations of the enzyme CYP2D6 which can help determine what the best form of cancer treatment is.



    Michael Gnant, M.D., professor of surgery at the Medical University of Vienna, said:


    "The results of this successful high-level international research collaboration are an important step forward in our quest to individualize breast cancer treatment and provide tailored care to women with breast cancer."



    Some breast cancer medications only work for certain women and it is vital that doctors assess each woman completely before carrying out treatment. For example, a previous study indicated that women with who had low levels of a protein known as pERK in their cancer-associated fibroblasts do not respond well to tamoxifen either.


    The researchers believe women with decreased metabolism of CYP2D6 should switch from tamoxifen to an aromatase inhibitor after two years, while those who are unable to metabolize the drug should avoid tamoxifen completely.


    For tamoxifen to work it needs to be completely metabolized into it's most active form called endoxifen. Dr. Goetz is currently working with the National Cancer Institute to try and develop a way that endoxifen can be given to women without worrying about how tamoxifen is metabolized. This could potentially eliminate the problem for women with an alteration of CYP2D6.

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    Default CYP2D6 Metabolism

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    clincancerres.aacrjournals.org/content/early/2012/12/04/1078-0432.CCR-12-2153.abstract?sid=1f63d0d8-dcc5-48f6-95ae-2c875a1d4659


    CYP2D6 Metabolism and Patient Outcome in the Austrian Breast and Colorectal Cancer Study Group Trial (ABCSG) 8


    1. * Corresponding Author:
    Matthew P Goetz, Oncology, Mayo Clinic, 200 First St. S.W., Rochester, MN, 55905, United States goetz.matthew@mayo.edu



    Abstract




    Background: Controversy exists regarding CYP2D6 genotype and tamoxifen efficacy. Methods: A matched case-control study was conducted utilizing the Austrian Breast and Colorectal Cancer Study Group Trial 8 that randomized post-menopausal women with estrogen receptor positive breast cancer to tamoxifen for 5 years (Arm A) or tamoxifen for 2 years followed by anastrozole for 3 years (Arm B). Cases had disease recurrence, contralateral breast cancer, second non-breast cancer, or died. For each case, controls were identified from the same treatment arm of similar age, surgery/radiation, and TNM stage. Genotyping was performed for alleles associated with no (PM; *3, *4, *6); reduced (IM; *10, and *41); and extensive (EM: absence of these alleles) CYP2D6 metabolism. Findings: The common CYP2D6 *4 allele was in Hardy Weinberg Equilibrium. In Arm A during the first 5 years of therapy, women with 2 poor alleles (PM/PM: OR=2.45, 95% CI: 1.05-5.73, p=0.04) and women with one poor allele (PM/IM or PM/EM: OR=1.67, 95% CI: 0.95-2.93, p=0.07) had a higher likelihood of an event than women with two extensive alleles (EM/EM). In years 3-5 when patients remained on tamoxifen (Arm A) or switched to anastrozole (Arm B), PM/PM tended towards a higher likelihood of a disease event relative to EM/EM (OR= 2.40, 95% CI: 0.86-6.66, p=0.09) among women on Arm A but not among women on Arm B (OR= 0.28; 95% CI: 0.03-2.30). Conclusion: In ABCSG8, the negative effects of reduced CYP2D6 metabolism were observed only during the period of tamoxifen administration, and not after switching to anastrozole.


    Published OnlineFirst December 4, 2012; doi: 10.1158/1078-0432.CCR-12-2153

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