Behaviour of vaginal epithelial maturation and sex hormone binding globulin in post-menopausal breast cancer patients during the first year of tamoxifen therapy

Analysis of the Ki-67 index in the vaginal epithelium of castrated rats treated with tamoxifen

OBJECTIVES

Vaginal atrophy and breast cancer are common conditions in postmenopausal women and tamoxifen is the standard endocrine treatment for hormone-sensitive tumors. The present study aimed to assess the effect of tamoxifen on Ki-67 protein expression in the vaginal epithelium of castrated rats.

MATERIAL AND METHODS

Forty Wistar-Hannover adult, virgin, castrated rats were randomly divided into two groups, group I (control, n=20) and group II (tamoxifen, n=20), receiving 0.5 ml of propylene glycol and 250 µg of tamoxifen diluted in 0.5 ml of propylene glycol, respectively, daily by gavage for 30 days. On the 31st day, the rats were euthanized and their vaginas were removed and fixed in 10% buffered formalin for the immunohistochemical study of Ki-67 protein expression. Data were analyzed by the Levene and Student's t tests (p<0.05).

RESULTS

The mean index of Ki-67 expression in the rat vagina of groups I and II was 4.04±0.96 and 26.86±2.19, respectively (p<0.001).

CONCLUSIONS

According to the results of the present study, tamoxifen, at the dose and treatment length used, induced a significant increase in the cell proliferation of the vaginal mucosa in castrated rats, as evaluated by Ki-67 protein expression.

[Levonorgestrel-releasing intrauterine device (Mirena) and breast cancer: what do we learn from literature for clinical practice?]

Annual occurrence of breast cancer is constantly increasing in France. In 2000, the number of breast cancer cases for women of 30-49 years was estimated at 9,918, which represents 23.7% of all breast cancer cases diagnosed that year. The levonorgestrel-releasing intrauterine device (IUD LNG) is one of the most frequently used coils in France. Because contraception is an important matter for women whose ovarian function survived cancer treatments, the question of whether to use such device on a woman with breast cancer has become a frequent and controversial gynaecological issue. With the review of available literature as a basis, we have tried to answer the following questions. First, whether the use of IUD LNG increases the risk of breast cancer: there is at the moment no "A" level answer available. According to the only study published, which may be considered "C" level, there is no such increase. Second, whether the use of IUD LNG counterbalances the endometrial effects of Tamoxifene: based on a limited level of evidence via a single randomised controlled trial on a small number of patients for one year only, this device appears to be able to prevent benign endometrial modifications. However, there is no conclusive study regarding its effectiveness on the prevention of endometrium adenocarcinoma caused by Tamoxifene. In addition, there are numerous uncertainties as to whether levonorgestrel presence in the plasma would have a systemic prejudicial impact. Third, whether a woman with a personal antecedent of breast cancer can safely use DIU LNG: it is necessary to remove it promptly upon suspicion or diagnosis, to dissuade its use in case of current cancer, and, in the event of cancer remission for more than 5 years, to generally avoid this contraceptive method except on a case by case basis and with a regular medical follow-up. In the latter situation, the use of IUD LNG can be considered only after a multidisciplinary collective formal decision and after the woman gave her informed consent.

Effects of tamoxifen on vaginal blood flow and epithelial morphology in the rat

Background

Tamoxifen, a selective estrogen receptor modulator with both estrogenic and anti-estrogenic activity, is widely used as adjuvant therapy in breast cancer patients. Treatment with tamoxifen is associated with sexual side effects, such as increased vaginal dryness and pain/discomfort during sexual activity. There have been limited investigations of the effect of tamoxifen on estrogen-dependent peripheral genital arousal responses. The objective of this study was to investigate the effects of tamoxifen on vaginal physiology in the rat.

Methods

Female Sprague-Dawley rats were subjected to sham surgery or bilateral ovariectomy. After 2 weeks, sham-operated rats were implanted with subcutaneous osmotic infusion pumps containing vehicle (control) or tamoxifen (150 μg/day). Ovariectomized rats were similarly infused with vehicle. After an additional 2 weeks, vaginal blood flow responses to pelvic nerve stimulation were measured by laser Doppler flowmetry and vaginal tissue was collected for histological and biochemical assay.

Results

Tamoxifen treatment did not change plasma estradiol concentrations relative to control animals, while ovariectomized rats exhibited a 60% decrease in plasma estradiol. Tamoxifen treatment caused a significant decrease in mean uterine weight, but did not alter mean vaginal weight. Vaginal blood flow was significantly decreased in tamoxifen-infused rats compared to controls. Similar to ovariectomized animals, estrogen receptor binding was increased and arginase enzyme activity was decreased in tamoxifen-infused rats. However, different from control and ovariectomized animals, the vaginal epithelium in tamoxifen-infused rats appeared highly mucified. Periodic acid-Schiff staining confirmed a greater production of carbohydrate-rich compounds (e.g. mucin, glycogen) by the vaginal epithelium of tamoxifen-infused rats.

Conclusion

The observations suggest that tamoxifen exerts both anti-estrogenic and pro-estrogenic effects in the vagina. These physiological alterations may eventually lead to vaginal atrophy and compromise sexual function.

Caution: Vaginal estradiol appears to be contraindicated in postmenopausal women on adjuvant aromatase inhibitors

BACKGROUND

Aromatase inhibitors (AI) are increasingly used in early breast cancer and there is a growing interest in associated long-term side-effects of profound estrogen suppression. Urogenital side-effects due to atrophic vaginitis are often managed with vaginal estrogen preparations. These are generally perceived to result in minimal systemic absorption of estrogen. We followed serum estradiol, follicle stimulating hormone (FSH) and luteinising hormone (LH) levels in seven postmenopausal women using vaginal estrogen preparations whilst on AIs for breast cancer.

PATIENTS AND METHODS

Serum was analysed for estradiol, FSH and LH at baseline then 2, 4, 7-10 and 12 weeks since commencement of vaginal estradiol. Estradiol was measured on an assay specifically developed for measuring low levels in postmenopausal women.

RESULTS

Serum estradiol levels rose from baseline levels < or = 5 pmol/l consistent with AI therapy to a mean 72 pmol/l at 2 weeks. By 4 weeks this had decreased to < 35 pmol/l in the majority (median 16 pmol/l) although significant further rises were seen in two women.

CONCLUSIONS

The vaginal estradiol tablet Vagifem significantly raises systemic estradiol levels, at least in the short term. This reverses the estradiol suppression achieved by aromatase inhibitors in women with breast cancer and is contraindicated.

Receptor Imaging in Oncology by Means of Nuclear Medicine: Current Status

To date, our understanding of the role of receptors and their cognate ligands in cancer is being successfully translated into the design and development of an arsenal of new, less toxic, and more specific anticancer drugs. Because most of these novel drugs are cytostatic, objective response as measured by morphologic imaging modalities (eg, computed tomography or magnetic resonance imaging) cannot be used as a surrogate marker for drug development or for clinical decision making. Positron emission tomography (PET) can be used to image and quantify the in vivo distribution of positron-emitting radioisotopes such as oxygen-15, carbon-11, and fluorine-18 that can be substituted or added into biologically relevant and specific receptor radioligands. Similarly, single-photon emission computed tomography (SPECT) can be used to image and quantify the in vivo distribution of receptor targeting compounds labeled with indium-111, technetium-99m, and iodine-123. By virtue of their whole-body imaging capacity and the absence of errors of sampling and tissue manipulation as well as preparation, both techniques have the potential to address locoregional receptor status noninvasively and repetitively. This article reviews available data on the in vivo evaluation of receptor systems by means of PET or SPECT for identifying and monitoring patients with sufficient receptor overexpression for tailored therapeutic interventions, and also for depicting tumor tissue and determining the currently largely unknown heterogeneity in receptor expression among different tumor lesions within and between patients.

Modest hormonal effects of soy isoflavones in postmenopausal women

Soy isoflavones have been hypothesized to exert hormonal effects in postmenopausal women. To test this hypothesis, we studied the effects of three soy powders containing different levels of isoflavones in 18 postmenopausal women. Isoflavones were consumed relative to bodyweight [control: 0.11 +/- 0.01; low isoflavone (low-iso): 1.00 +/- 0.01; high isoflavone (high-iso): 2.00 +/- 0.02 mg/kg/day] for 93 days each in a randomized crossover design. Blood was collected on day 1 of the study (baseline) and days 36-38, 64-66, and 92-94 of each diet period, for analysis of estrogens, androgens, gonadotropins, sex hormone binding globulin (SHBG), prolactin, insulin, cortisol, and thyroid hormones. Vaginal cytology specimens were obtained at baseline and at the end of each diet period, and endometrial biopsies were performed at baseline and at the end of the high-iso diet period, to provide additional measures of estrogen action. Overall, compared with the control diet, the effects of the low-iso and high-iso diets were modest in degree. The high-iso diet resulted in a small but significant decrease in estrone-sulfate (E1-S), a trend toward lower estradiol (E2) and estrone (E1), and a small but significant increase in SHBG. For the other hormones, the few significant changes noted were also small and probably not of physiological importance. There were no significant effects of the low-iso or high-iso diets on vaginal cytology or endometrial biopsy results. These data suggest that effects of isoflavones on plasma hormones per se are not significant mechanisms by which soy consumption may exert estrogen-like effects in postmenopausal women. These data also show that neither isoflavones nor soy exert clinically important estrogenic effects on vaginal epithelium or endometrium.