Effects of the selective estrogen receptor modulator, raloxifene, on carotid artery pulsatility index in postmenopausal women

OBJECTIVE

Estrogen replacement therapy after menopause reduces the incidence of arterial disease and cerebrovascular events. The reduced incidence also seems to be due to a positive effect of estrogens on brain blood flow as shown by a decrease in the carotid artery pulsatility index. Raloxifene, a second-generation selective estrogen receptor modulator, has aroused considerable interest because of its tissue-specific agonist-antagonist effect on estrogen receptors. However, there have been no studies on the effect of raloxifene on carotid blood flow after menopause.

METHODS

A total of 66 healthy women in postmenopause for more than a year were divided randomly into 2 groups: the first group (n = 33; mean age +/- SD, 53.3 +/- 5.2 years) was treated with raloxifene (one 60-mg capsule per day) for 6 months, and the other group (n = 33; mean age +/- SD, 51.9 +/- 4 years) was untreated. Doppler ultrasonography was used to measure carotid artery pulsatility index (PI) at the beginning of the study and at 2-month intervals.

RESULTS

A reduction in carotid artery PI was observed in all patients receiving raloxifene. No significant changes were observed in the control group. The reduction with respect to baseline values was 6.1%(P <.05) after 2 months, 11.2% (P <.05) after 4 months, and 13.2% (P <.05) after 6 months of therapy. The higher the baseline PI, the greater was its reduction after therapy.

CONCLUSIONS

After 6 months of therapy, raloxifene induced a reduction in PI similar to that reported after estrogen therapy. The present results further our understanding of the mechanisms by which raloxifene might reduce the incidence of cardiovascular disease in postmenopausal women.

Effect of 1 year of discontinuation of raloxifene or estrogen therapy on bone mineral density after 5 years of treatment in healthy postmenopausal women

The beneficial effects of hormone replacement therapy (HRT), selective estrogen receptor modulators (SERMs), or bisphosphonates in the prevention and treatment of osteoporosis in postmenopausal women have been well established. However, little is known about the effects of discontinuation of treatment on bone mineral density. We investigated the effect of 1 year of discontinuation of the SERM raloxifene (Ral; 60 mg and 150 mg), conjugated equine estrogen (CEE; 0.625 mg), and placebo after 5 years of treatment in a double-blind, randomized study. Thirty-eight of 59 healthy and hysterectomized postmenopausal women (mean age 55 years) completed the treatment and 1 year follow-up period. Lumbar spine and femoral neck bone mineral density (BMD) were performed with dual-energy X-ray absorptiometry, before, during, and at the end of treatment, as well as after 1 year of discontinuation of therapy. One year of discontinuation significantly reduced the mean lumbar spine BMD in the raloxifene- and estrogen-treated women (p < 0.05), whereas mean femoral neck BMD was reduced significantly only in women treated with 60 mg Ral (p < 0.05). The mean percentage change (+/-SD) in lumbar spine BMD was: CEE, -6.2% (+/-3.7%); Ral 60 mg, -2.4% (+/-2.4%); Ral 150 mg, -2.6% (+/-3.1%); and placebo, -1.6% (+/-4.3%). Our results show that 5 years of treatment with either Ral or CEE did not protect against bone loss after 1 year of withdrawal of therapy, and that the rate of bone loss was not significantly different from that of placebo-treated women.

Sequence- and time-dependent antagonism between raloxifene and methotrexate in human breast cancer cells

The selective estrogen receptor modulator (SERM) and an agent for the prevention of osteoporosis in postmenopausal women, raloxifene (Ral), decreased high-dose methotrexate (MTX) cytotoxicity in MCF-7 breast cancer cells. When Ral is given at least 24 hours prior to MTX, the resultant interaction is antagonistic. However, when breast cancer cells are exposed to Ral 24 hours after MTX, the interaction between Ral and MTX is not antagonistic. The proliferation of cells exposed to 10 microM Ral and 10 microM MTX alone or in combination with Ral 24 hours prior to MTX was in had the following order: MTX > Ral 24 hours prior to MTX > Ral. MTX administration 24 hours prior to Ral had the following inhibitory effects on the growth of cells: MTX 24 hours prior to Ral > or = MTX > Ral 24 hours prior to MTX > Ral > control (no drug exposure). To determine if the antagonistic interaction between Ral and MTX was a function of sequence and time, cells were exposed to Ral 24 hours and 36 hours prior to MTX exposure. The percentages of control rates were 43.48 +/- 3.90% and 54.43 +/- 2.93%, respectively, from a 24 hours and 36 hours exposure of Ral prior to MTX. The growth rates after 24 h and 36 h exposures to MTX alone were 30.30 +/- 0.61% and 33.11 +/- 2.27% of control rates, respectively. These studies suggest that: (a) the interactions between Ral and MTX are sequence-dependent; (b) Ral antagonizes the effect of MTX when Ral administration precedes MTX; and (c) Ral antagonism to MTX is a function of time.

A 2-year, randomized, comparative, placebo-controlled study on the effects of raloxifene on lipoprotein(a) and homocysteine

OBJECTIVES

Lipoprotein(a) (Lp(a)) and homocysteine (Hcy) are independent cardiovascular risk factors, which have been shown to be lowered by hormone replacement therapy (HRT). In this 2-year study, the long-term effects of raloxifene (Rlx) in two doses, on Lp(a) and Hcy, were studied and compared with the effects of continuously combined hormone replacement therapy (ccHRT).

METHODS

In a prospective, randomized, double-blind, placebo-controlled 2-year study, 95 healthy, non-hysterectomized, early postmenopausal women, received daily either oral Rlx 60 mg (N=24) or 150 mg (N=23), ccHRT (conjugated equine estrogens 0.625 mg plus medroxyprogesterone acetate 2.5 mg; N=24) or placebo (N=24). Fasting serum Lp(a) and plasma Hcy concentrations were measured at baseline and at 6, 12 and 24 months.

RESULTS

The mean individual changes compared to baseline after 24 months were for Lp(a): Rlx 60: - 5%, Rlx 150: -7%, ccHRT: -34%, placebo: +1% and for Hcy: Rlx 60: -3%, Rlx 150: -4%, ccHRT: -4%, placebo: +6%. ANCOVA was significant for Lp(a) under ccHRT versus placebo (P=0.001) and for Lp(a) under ccHRT versus each of the two Rlx groups (P<0.05).

CONCLUSIONS

Long-term treatment with Rlx was not as effective as ccHRT in lowering Lp(a). Although not significant and without an obvious dose-related response, the Hcy values showed the same trend for each treatment arm, which is in line with data reported earlier.

Effects of raloxifene after tamoxifen on breast and endometrial tumor growth in athymic mice

BACKGROUND

In patients with early-stage breast cancer, 5 years of treatment with the selective estrogen receptor modulator (SERM) tamoxifen reduces breast cancer recurrence and mortality, whereas more than 5 years of tamoxifen does not further reduce breast cancer recurrence and doubles the risk of endometrial cancer. We evaluated the effects on tumor growth of raloxifene, another SERM, after tamoxifen treatment in mouse models of breast and endometrial cancers.

METHODS

Athymic, ovariectomized mice were bitransplanted with tumors derived from human breast cancer and endometrial cancer cells that either were tamoxifen-naive or had been exposed to tamoxifen for short (6 months) or long (>5 years) terms. The effects of raloxifene (two dose levels) and tamoxifen on tumor growth in the presence and absence of low-dose estrogen were evaluated. All statistical tests were two-sided.

RESULTS

Raloxifene was less effective than tamoxifen in blocking the stimulatory effects of low-dose estrogen on the growth of tamoxifen-naive breast (P<.001) and endometrial (P =.001) tumors. Raloxifene and tamoxifen had similar inhibitory effects on the growth of short-term tamoxifen-exposed breast tumors. Raloxifene and tamoxifen had similar stimulatory effects on the growth of breast and endometrial tumors that had been exposed to at least 5 years of tamoxifen. However, neither drug blocked the stimulatory effects of estrogen on the growth of these tumors. Raloxifene was less effective than tamoxifen (P<.001) in blocking the stimulatory effects of estrogen on endometrial tumors that had been exposed to tamoxifen in the past.

CONCLUSIONS

Raloxifene and tamoxifen had similar effects on these mouse models of tamoxifen-naive and tamoxifen-resistant breast and endometrial cancer. Treatment with raloxifene following 5 years of adjuvant tamoxifen may not further decrease breast cancer recurrence and may increase endometrial cancer incidence.

Effects of estrogen-progestin and raloxifene therapy on nitric oxide, prostacyclin and endothelin-1 synthesis

This randomized double-blind study was conducted to investigate the effects of 17 beta-estradiol plus norethisterone acetate, and raloxifene, on nitric oxide (NO), prostacyclin (PGI2) and endothelin-1 (ET-1) serum levels in postmenopausal women. Treatment was initiated after a 28-50 day placebo period. Fourteen women were treated daily with 17 beta-estradiol 2 mg plus norethisterone acetate 1 mg (E2 + NETA), and 14 with raloxifene HCl 60 mg for a period of 6 months. Serum NO, PGI2 and ET-1 levels were estimated at baseline, after placebo, and at months 3 and 6. E2 + NETA decreased NO levels significantly, while raloxifene did not cause any appreciable change. Both regimens decreased PGI2 levels and ET-1 levels significantly. Finally, E2 + NETA and raloxifene increased the NO/ET-1 ratio by 61.4% and 81.1%, respectively. In conclusion, both regimens may exert a cardio-protective effect by decreasing ET-1 levels and increasing the NO/ET-1 ratio. In contrast, both regimens had a negative influence on PGI2 levels.

Current status and future innovations of hormonal agents, chemotherapy and investigational agents in endometrial cancer

The median survival of women with advanced or recurrent endometrial cancer is less than one year. Only half the women with early stage endometrial cancer and poor prognostic factors such as high grade or deep myometrial invasion will survive for 5 years. Over the past decade, incredible strides have been taken in evaluating systemic therapy for this disease. However, survival rates remain poor. A literature search was conducted using CANCERLIT, EMBASE, Medline, Investigational Drug database (Current Drug Ltd.) and R&D Focus (IMSworld Publications). The references of the articles were also explored. Search terms included: endometrial cancer, chemotherapy, endocrine/hormonal therapies, molecular biologics, and specific drug names. Progestin therapy offers a 10-20% response rate and survival of less than 1 year. Progestins are most effective in women with well-differentiated tumours and a long disease-free interval. There is no role for adjuvant progestin therapy in early stage disease. Single-agent chemotherapy with the most activity includes ifosfamide, cisplatin/carboplatin, doxorubicin and paclitaxel. Combination chemotherapy provides a response rate of 40-60%; however, median survival is still less than a year. New areas of research include the identification and evaluation of new active endocrine therapies (i.e. LY353381.HCl and letrozole), chemotherapeutics (i.e. herceptin), evaluating chemotherapeutic agents in combination (i.e. paclitaxel, doxorubicin and platinum), in addition to radiation or instead of radiation. New avenues under development involve the specific molecules and pathways responsible for the initiation and growth of endometrial carcinoma, including: tumour suppressor genes, DNA mismatch repair genes, oncogenes, molecules involved in adhesion and invasion and angiogenesis. Further significant advances in radiotherapy, hormonal therapy and chemotherapy are unlikely. Exciting developments in understanding the molecules involved in tumour development and metastasis will allow the development of specific and selective inhibitors.

Differential effects of raloxifene and continuous combined hormone replacement therapy on biochemical markers of cardiovascular risk: results from the Euralox 1 study

OBJECTIVE

To compare the effects of the selective estrogen receptor modulator (SERM) raloxifene (Evista) and a continuous combined hormone replacement therapy (ccHRT) formulation containing estradiol and norethisterone acetate (Kliogest) on lipid and fibrinogen levels of postmenopausal women.

METHODS

Euralox 1 was a prospective, randomized, double-blind trial. After a placebo wash-out, healthy postmenopausal women (n = 1008, average age 56.1 +/- 4.9 years) with a health risk profile that suggested a potential benefit from either treatment were randomly assigned to either 60 mg raloxifene or ccHRT consisting of 2 mg estradiol and 1 mg norethisterone acetate (NETA) per day for 6 months.

MEASUREMENTS

Total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol with its fractions HDL2 and HDL3, the LDL/HDL ratio, triglycerides and fibrinogen were assessed at baseline and after 6 months or on early drop-out.

RESULTS

Baseline values were comparable between the two groups. Blood samples of 841 women (83.4%) were available at baseline and endpoint. Total and LDL cholesterol decreased statistically significantly from baseline to endpoint in both treatment arms (by 7.2% and 3.8% with raloxifene and by 13.0% and 8.9% with ccHRT, respectively). Raloxifene produced a statistically significant increase in HDL cholesterol by 4.2%, while ccHRT induced a decline by 9.5%. Triglycerides were moderately suppressed with raloxifene and ccHRT, by 3.6 and 5.4%, respectively. Fibrinogen fell by 7.0% with raloxifene and rose by 3.6% with ccHRT.

CONCLUSIONS

Continuous combined HRT was associated with decreases in total cholesterol and LDL cholesterol about twice as large as with raloxifene, but also with a decrease in HDL cholesterol. The smaller decreases in total cholesterol and LDL cholesterol associated with raloxifene were accompanied by an increase in HDL cholesterol and a decrease in fibrinogen. In conclusion, raloxifene affects fibrinogen concentrations and the overall cholesterol profile more favorably than ccHRT; these differences may have important implications for the reduction of cardiovascular disease.

Effect of raloxifene on IGF-I and IGFBP-3 in postmenopausal women with breast cancer

The effect on the IGF system of 60 mg and 600 mg daily of raloxifene administered for 2 weeks prior to surgery was investigated in 37 postmenopausal women with breast cancer. Raloxifene significantly decreased insulin-like growth factor (IGF-I) as compared to placebo (P < 0.05) with no dose-response relationship. No significant change was observed in IGFBP-3, while the IGF-I/IGFBP-3 molar ratio was decreased by treatment, with a statistically significant effect only for the higher dose. Given that high plasma levels of IGF-I have been suggested as a risk factor for breast cancer, these findings provide further support for the potential activity of raloxifene in breast cancer prevention.

Evaluation and treatment of postmenopausal osteoporosis

Osteoporosis is a prevalent condition among elderly women and is associated with an increased risk for fractures. With the burgeoning size of the elderly population, a practitioner is likely to face many questions regarding the evaluation and management of postmenopausal osteoporosis. This review discusses and compares available therapies. All women should have adequate calcium and vitamin D intake. Women diagnosed as having osteoporosis should be evaluated for secondary causes of osteoporosis and risk factors for falls. For women with postmenopausal osteoporosis, therapy with hormone replacement, bisphosphonates (alendronate sodium or risedronate sodium), raloxifene hydrochloride, or calcitonin should be considered. The results of ongoing studies will help refine the strategies used for management of postmenopausal osteoporosis.

Effect of raloxifene on breast cancer cell Ki67 and apoptosis: a double-blind, placebo-controlled, randomized clinical trial in postmenopausal patients

PURPOSE

Raloxifene is a selective estrogen receptor (ER) modulator approved for prevention and treatment of postmenopausal osteoporosis. This is an exploratory study of raloxifene in primary breast cancer patients.

EXPERIMENTAL DESIGN

Postmenopausal women (50-80 years of age), with histological or cytological diagnosis of stage I or II primary breast cancer, were randomly assigned to 14 days of placebo, 60 mg/day raloxifene, or 300 mg twice daily (600 mg/day) of raloxifene. A core biopsy of the primary tumor was obtained before therapy, and a representative sample of the excised tumor was obtained from the operative specimen after treatment. Paired baseline and endpoint biopsies from each patient were analyzed for Ki67, apoptosis, and estrogen and progesterone receptors. Treatment group differences in efficacy measurements were primarily evaluated for baseline-to-endpoint change and percentage change using a one-way ANOVA with treatment as the fixed effect.

RESULTS

Of 167 enrolled patients, 143 had evaluable efficacy data. Most breast cancer cases were invasive (98.6%), stage I (76.6%), and ER-positive (83.2%). In patients with ER-positive tumors, Ki67 increased 7% from baseline on placebo and decreased by 21% on 60 mg/day raloxifene (P = 0.015 versus placebo) and by 14% on 600 mg/day raloxifene (P = 0.064 versus placebo). Raloxifene did not affect apoptosis. ER decreased significantly with 60 mg/day or 600 mg/day raloxifene compared with placebo (P < 0.01 for each comparison). Raloxifene had no statistically significant effects on Ki67 among patients with ER-negative tumors. There were no treatment differences in adverse events.

CONCLUSION

In this exploratory trial, 60 mg/day raloxifene showed a significant antiproliferative effect in ER-positive breast cancer, demonstrated by the decrease in Ki67, with no effect in ER-negative cancer. This provides support for raloxifene having a breast cancer preventive effect in postmenopausal women.

Raloxifene reduces impedance to flow within the uterine artery in early postmenopausal women: a 2-year randomized, placebo-controlled, comparative study

OBJECTIVE

We sought to investigate the long-term effect of raloxifene and continuous combined hormone replacement therapy (ccHRT) on impedance to flow within the uterine artery in postmenopausal women.

STUDY DESIGN

A prospective, randomized, double-blind, placebo-controlled 2-year study was performed in 95 postmenopausal women. They received either 60 mg of raloxifene daily (raloxifene 60 group), 150 mg of raloxifene daily (raloxifene 150 group), ccHRT, or placebo. At baseline and thereafter every 6 months, color Doppler ultrasonography was used to measure the pulsatility index (PI) of the uterine artery.

RESULTS

After 24 months of treatment, compared with placebo, significant decreases were found in the PI in the raloxifene 150 group (P = .021) and in the ccHRT group (P = .007). In the raloxifene 150 group compared with the placebo group, after 6 and 24 months, decreases were observed in median PI of -5% and -15%, respectively, and in the ccHRT group decreases of -2% and -19%, respectively, were found.

CONCLUSION

Long-term use of 150 mg of raloxifene daily or ccHRT reduces impedance to flow within the uterine artery. This indicates that high-dose raloxifene may exert cardiovascular protection.

Oestrogenic effects of neonatal administration of raloxifene on hypothalamic-pituitary-gonadal axis in male and female rats

Selective oestrogen receptor modulators constitute a family of drugs that are used increasingly in the management of oestrogen-associated pathology. Raloxifene is a selective oestrogen receptor modulator that is used to treat and prevent osteoporosis in post-menopausal women. The actions of raloxifene on bone, breast, uterus and serum cholesterol concentrations have been widely analysed, but very few studies have investigated the possible actions of this drug on the central nervous system. The central nervous system of the newborn rat is very sensitive to oestrogen action. In this study a series of experiments was conducted to analyse the effects of different doses of raloxifene (50, 100, 250 or 500 microg per rat per day) administered to neonatal rats on days 1-5 of age. Female rats treated with raloxifene showed decreased gonadotrophin secretion, hyperprolactinaemia, advanced vaginal opening, decreased body weight, persistent presence of cornified epithelial cells in vaginal smears, anovulation, inhibition of positive feedback between oestradiol and LH, and infertility. Male rats showed delayed balanopreputial separation, reduced body weight and hyperprolactinaemia. All these changes resemble those obtained after neonatal administration of oestradiol benzoate, thus indicating, for the first time, that raloxifene exerts an oestrogenic action on the hypothalamic-pituitary structures controlling reproductive function in rats.

Effects of raloxifene and hormone replacement therapy on markers of serum atherogenicity in healthy postmenopausal women

OBJECTIVE

To determine the effect of raloxifene (RLX) and hormone replacement therapy (HRT) on non-high density lipoprotein cholesterol (non-HDL-C) levels and the apolipoprotein-B/apolipoprotein-A1 (apo-B/apo-A1) concentration ratio, markers of serum atherogenicity, in postmenopausal women.

METHODS

Three hundred and ninety healthy postmenopausal women aged 45-72 years were enrolled in a double-blind, randomized, placebo-controlled, parallel trial at eight outpatient sites in the United States. Women were randomly assigned to receive continuous combined HRT (0.625 mg/day conjugated equine estrogen and 2.5 mg/day medroxyprogesterone acetate), 60 or 120 mg/day raloxifene, or placebo for 6 months. Serum concentrations of non-HDL cholesterol and the apo-B/apo-A1 concentration ratio were measured in serum samples obtained at baseline and at 6 months of treatment.

RESULTS

At 6 months, non-HDL-C and apo-B/apo-A1 were significantly reduced by 60 mg/day RLX (10 and 11%, respectively), 120 mg/day RLX (9 and 12%, respectively) and HRT (10 and 12%, respectively), compared with placebo. The effect of all treatments to lower non-HDL-C and apo-B/apo-A1 was greatest in women with hypercholesterolemia (total-C>240 mg/dl) at baseline. Among women with undesirable (>160 mg/dl) non-HDL cholesterol at baseline, RLX and HRT lowered the percentage of these women remaining above this threshold after 6 months (placebo, 89%; 60 mg/day RLX, 61%; 120 mg/day RLX, 74%; HRT, 58%). Similar results were observed for women with high (>190 mg/dl) non-HDL cholesterol at baseline.

CONCLUSION

In healthy postmenopausal women, RLX and HRT lower serum non-HDL-C and apo-B/apo-A1, indicators of serum atherogenicity, to a similar extent.

Gonadotropins at menopause: the influence of obesity, insulin resistance, and estrogens

Obese, postmenopausal women have lower FSH levels. To determine whether this is due to higher estrogen exposure, we compared feedback gonadotropin sensitivity and its relation to insulin resistance in four groups of obese and lean, postmenopausal women. Group one was treated with 400 mg troglitazone (TG) daily for two weeks; 150 clomiphene citrate (CC) was added daily for the second week. Group two received 150 mg CC daily for a week. Group three received 1000 mg metformin (MET) daily for two weeks, with 120 mg raloxifene (RAL) added during the second week. Group four received 120 mg RAL for a week. Before and after each period, a serum pool was obtained from samples taken every minute during a 10 ml interval. The women recruited for this study were categorized as obese or lean based on BMI >/= 29 or BMI < 29, respectively. Obese, menopausal women had lower FSH (45.5 IU/l) and LH (16.2 IU/l) values than those of lean (64.1 IU/l and 23.0 IU/l), but the obese menopausal women had higher leptin, DHEAS, glucose, insulin, and HOMA-IR levels. Log [FSH] was associated with BMI (r = -0.53, P < 0.000001) and number of pregnancies (r = -0.37, P = 0.0009). TG treatment did not change HOMA-IR or gonadotropin levels, but DHEAS and androstenedione levels decreased significantly. CC alone or together with TG, diminished FSH (-7.9 and -9.2) and LH (-2.5 and -3.6) concentrations, with a greater reduction in lean women. MET reduced glucose and the HOMA-IR index without affecting gonadotropin or steroid levels.

CONCLUSIONS

obese, menopausal women have lower FSH levels due to greater estrogen exposure, by mechanisms unrelated to insulin resistance.

[Hormone replacement and selective estrogen receptor modulators (SERMS) in the prevention and treatment of postmenopausal osteoporosis]

For many years, hormone replacement therapy (HRT) has been regarded as one of the most reliable means of prophylaxis and treatment for postmenopausal osteoporosis. As HRT ameliorates menopausal symptoms, it is widely prescribed among early postmenopausal women. A variety of different modes of replacement that suit each individual requirement are available in terms of schedule (cyclic or combined application of gestagens) and route of application (oral or transdermal). HRT effectively prevents spinal bone loss and delays bone loss at the hip up to a very old age. With continued use after menopause, HRT might theoretically halve the incidence of vertebral and hip fractures. However, long-term use or use of HRT in old age is rarely practiced, and the actual benefit of a transient use for future fracture prevention remains unclear. Raloxifene is the first member of the novel class of selective estrogen receptor modulators (SERMs) that has been approved for the prophylaxis and treatment of postmenopausal osteoporosis. It combines the positive effects of estrogen on the skeleton with estrogen-antagonistic effects on sex tissues. Thus, raloxifene maintains bone mass and decreases the incidence of vertebral fractures in osteoporotic women, but avoids many of the side effects that are responsible for the poor long-term compliance to HRT such as resumption or continuation of regular menses, breast tenderness, or breast cancer. It even markedly reduces the risk of breast cancer. Both estrogen and raloxifene are characterized by a large number of extraskeletal effects that have to be taken into account when counseling postmenopausal women on the use of these agents for the prevention or treatment of osteoporosis.

Estrogenic and antiestrogenic effects of raloxifene on collagen metabolism in breast cancer MCF-7 cells

We compared the effects of different concentrations of raloxifene (1, 4 and 10 microM) on collagen biosynthesis, gelatinolytic and prolidase activities and matrix metalloproteinase (MMP) expression (MMP-2 and MMP-9) in estradiol-stimulated (2 nM) breast cancer MCF-7 cells. Raloxifene inhibited in a dose-dependent manner the proliferation of MCF-7 cells, independently of the presence or absence of estradiol in the growth medium. Raloxifene at concentrations of 1 microM and 4 microM inhibited collagen biosynthesis by about 10-fold and prolidase activity by about 50%, while at a concentration of 10 microM it inhibited these processes by only about 25%. This phenomenon was accompanied by differences in gelatinolytic activity and MMP (MMP-2 and MMP-9) expression as demonstrated by zymography and Western immunoblot analysis, respectively. In estrogen-stimulated MCF-7 cells, cultured in the presence of 1 microM raloxifene, a dramatic increase in the activity of both collagenases was found. In contrast, addition of raloxifene at a concentration of 10 microM to the medium of the cells resulted in restoration of gelatinolytic activity to that found in control cells. Similarly, but at both doses (1 and 10 microM), raloxifene was able to reduce MMP-2 expression in the cells. However, when used alone (without estradiol) a concentration of 1 microM raloxifene strongly stimulated MMP-2 expression, while at a concentration of 10 microM the effect was not observed. In the case of MMP-9, only trace amounts of this gelatinase were detected, although in contrast to MMP-2, an increase in its expression was noticed at a concentration of 10 microM raloxifene. The data raise the possibility that in estrogen-stimulated MCF-7 cells, raloxifene at low concentrations (1 and 4 microM) evokes antiestrogenic effect on collagen biosynthesis and prolidase activity on the one hand, and an estrogenic effect on gelatinolytic activity on the other, while at higher concentrations (about 10 microM) it evokes an estrogenic effect on collagen biosynthesis and prolidase activity, and an antiestrogenic effect on gelatinolytic activity. Our data suggest that the effects of raloxifene on collagen synthesis, prolidase and metalloproteinase activities in breast cancer may explain its role in the prevention of breast cancer development.

Effects of postmenopausal hormone replacement therapy on lipid, lipoprotein, and apolipoprotein (a) concentrations: analysis of studies published from 1974-2000

OBJECTIVE

To establish reference estimates of the effects of different hormone replacement therapy (HRT) regimens on lipid and lipoprotein levels.

DESIGN

Review and pooled analysis of prospective studies published up until the year 2000.

SETTING

Clinical trials centers, hospitals, menopause clinics.

PATIENT(S)

Healthy postmenopausal women.

INTERVENTION(S)

Estrogen alone, estrogen plus progestogen, tibolone, or raloxifene in the treatment of menopausal symptoms.

MAIN OUTCOME MEASURE(S)

Serum high- and low-density lipoprotein (HDL and LDL) cholesterol, total cholesterol, triglycerides, and lipoprotein (a).

RESULT(S)

Two-hundred forty-eight studies provided information on the effects of 42 different HRT regimens. All estrogen alone regimens raised HDL cholesterol and lowered LDL and total cholesterol. Oral estrogens raised triglycerides. Transdermal estradiol 17-beta lowered triglycerides. Progestogens had little effect on estrogen-induced reductions in LDL and total cholesterol. Estrogen-induced increases in HDL and triglycerides were opposed according to type of progestogen, in the order from least to greatest effect: dydrogesterone and medrogestone, progesterone, cyproterone acetate, medroxyprogesterone acetate, transdermal norethindrone acetate, norgestrel, and oral norethindrone acetate. Tibolone decreased HDL cholesterol and triglyceride levels. Raloxifene reduced LDL cholesterol levels. In 41 studies of 20 different formulations, HRT generally lowered lipoprotein (a).

CONCLUSION(S)

Route of estrogen administration and type of progestogen determined differential effects of HRT on lipid and lipoprotein levels. Future work will focus on the interpretation of the clinical significance of these changes.

Cancer prevention and early detection

Advances in the area of cancer prevention and early detection are being made constantly. Basic epidemiologic research continues to provide insight into the impact of carcinogen exposure and the development of cancer. It is exciting to note that the study of Tamoxifen and Raloxifene chemoprevention trial is successfully recruiting women, including minority women, to participate. This large chemoprevention trial is providing much insight into how to recruit and retain women to take a chemoprevention agent to ultimately prevent the development of cancer. Advances also are being made in the knowledge base of how to best detect cancer in asymptomatic people. The best screening tool recommendation for the early detection of colorectal cancer remains controversial. Screening for colorectal cancer, however, is the only way to ultimately decrease the morbidity and mortality associated with the disease. Oncology nurses need to accurately risk for colorectal cancer and provide patients with the necessary information to make an informed choice about the most appropriate screening for their situation. Oncology nurses need to be familiar with new research and advances in cancer prevention and early detection so they can share information with patients and their families.