ContextTamoxifen is approved for the reduction of breast cancer risk, and raloxifene has demonstrated a reduced risk of breast cancer in trials of older women with osteoporosis.ObjectiveTo compare the relative effects and safety of raloxifene and tamoxifen on the risk of developing invasive breast cancer and other disease outcomes.Design, Setting, and PatientsThe National Surgical Adjuvant Breast and Bowel Project Study of Tamoxifen and Raloxifene trial, a prospective, double-blind, randomized clinical trial conducted beginning July 1, 1999, in nearly 200 clinical centers throughout North America, with final analysis initiated after at least 327 incident invasive breast cancers were diagnosed. Patients were 19 747 postmenopausal women of mean age 58.5 years with increased 5-year breast cancer risk (mean risk, 4.03% [SD, 2.17%]). Data reported are based on a cutoff date of December 31, 2005.InterventionOral tamoxifen (20 mg/d) or raloxifene (60 mg/d) over 5 years.Main Outcome MeasuresIncidence of invasive breast cancer, uterine cancer, noninvasive breast cancer, bone fractures, thromboembolic events.ResultsThere were 163 cases of invasive breast cancer in women assigned to tamoxifen and 168 in those assigned to raloxifene (incidence, 4.30 per 1000 vs 4.41 per 1000; risk ratio [RR], 1.02; 95% confidence interval [CI], 0.82-1.28). There were fewer cases of noninvasive breast cancer in the tamoxifen group (57 cases) than in the raloxifene group (80 cases) (incidence, 1.51 vs 2.11 per 1000; RR, 1.40; 95% CI, 0.98-2.00). There were 36 cases of uterine cancer with tamoxifen and 23 with raloxifene (RR, 0.62; 95% CI, 0.35-1.08). No differences were found for other invasive cancer sites, for ischemic heart disease events, or for stroke. Thromboembolic events occurred less often in the raloxifene group (RR, 0.70; 95% CI, 0.54-0.91). The number of osteoporotic fractures in the groups was similar. There were fewer cataracts (RR, 0.79; 95% CI, 0.68-0.92) and cataract surgeries (RR, 0.82; 95% CI, 0.68-0.99) in the women taking raloxifene. There was no difference in the total number of deaths (101 vs 96 for tamoxifen vs raloxifene) or in causes of death.ConclusionsRaloxifene is as effective as tamoxifen in reducing the risk of invasive breast cancer and has a lower risk of thromboembolic events and cataracts but a nonstatistically significant higher risk of noninvasive breast cancer. The risk of other cancers, fractures, ischemic heart disease, and stroke is similar for both drugs.Trial Registrationclinicaltrials.gov Identifier: NCT00003906Published online June 5, 2006 (doi:10.1001/jama.295.23.joc60074).

https://jamanetwork.com/journals/jama/articlepdf/203040/JOC60074.pdf

Effects of tamoxifen vs raloxifene on the risk of developing invasive breast cancer and other disease outcomes: the NSABP Study of Tamoxifen and Raloxifene (STAR) P-2 trial.

Background: Initial fi ndings from the National Surgical Adjuvant Breast and Bowel Project Breast Cancer Prevention Trial (P-1) demonstrated that tamoxifen reduced the risk of estrogen receptor – positive tumors and osteoporotic fractures in women at increased risk for breast cancer. Side effects of varying clinical signifi cance were observed. The trial was unblinded because of the positive results, and follow-up continued. This report updates our initial fi ndings. Methods: Women (n = 13 388) were randomly assigned to receive placebo or tamoxifen for 5 years. Rates of breast cancer and other events were compared by the use of risk ratios (RRs) and 95% confi dence intervals (CIs). Estimates of the net benefi t from 5 years of tamoxifen therapy were compared by age, race, and categories of predicted breast cancer risk. Statistical tests were two-sided. Results: After 7 years of follow-up, the cumulative rate of invasive breast cancer was reduced from 42.5 per 1000 women in the placebo group to 24.8 per 1000 women in the tamoxifen group (RR = 0.57, 95% CI = 0.46 to 0.70) and the cumulative rate of noninvasive breast cancer was reduced from 15.8 per 1000 women in the placebo group to 10.2 per 1000 women in the tamoxifen group (RR = 0.63, 95% CI = 0.45 to 0.89). These reductions were similar to those seen in the initial report. Tamoxifen led to a 32% reduction in osteoporotic fractures (RR = 0.68, 95% CI = 0.51 to 0.92). Relative risks of stroke, deep-vein thrombosis, and cataracts (which increased with tamoxifen) and of ischemic heart disease and death (which were not changed with tamoxifen) were also similar to those initially reported. Risks of pulmonary embolism were approximately 11% lower than in the original report, and risks of endometrial cancer were about 29% higher, but these differences were not statistically signifi cant. The net benefi t achieved with tamoxifen varied according to age, race, and level of breast cancer risk. Conclusions: Despite the potential bias caused by the unblinding of the P-1 trial, the magnitudes of all benefi cial and undesirable treatment effects of tamoxifen were similar to those initially reported, with notable reductions in breast cancer and increased risks of thromboem bolic events and endometrial cancer. Readily identifi able sub sets of individuals comprising 2.5 million women could derive a net benefi t from the drug. [J Natl Cancer Inst 2005;97:1652 – 62]

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Tamoxifen for the Prevention of Breast Cancer: Current Status of the National Surgical Adjuvant Breast and Bowel Project P-1 Study

Until recently, tamoxifen, a nonsteroidal antiestrogen, was the mainstay of endocrine treatment of breast cancer. However, new aromatase inhibitors that are many times more potent and specific than the first such agent, aminoglutethimide, are changing the management of breast cancer in postmenopausal women. This review discusses the role of aromatase inhibitors such as letrozole, anastrozole, and exemestane in the treatment of breast cancer.

Aromatase Inhibitors in Breast Cancer

The selective estrogen-receptor modulators, or SERMs, chemically diverse nonsteroid compounds, have tertiary structures that permit binding to the estrogen receptor. These compounds have either selective agonist or antagonist effects, depending on the target tissue. This article reviews current information concerning the molecular basis of SERM action and the tissue-selective agonist–antagonist effects of this class of medication. The article also offers a perspective on the therapeutic uses of SERMs and compares the SERMs with estrogen and nonestrogen alternatives.

A Hamed

Papers

First results from the International Breast Cancer Intervention Study (IBIS-I): a randomised prevention trial.