Indicators of lifetime estrogen exposure: effect on breast cancer incidence and interaction with raloxifene therapy in the multiple outcomes of raloxifene evaluation study participants.

PURPOSE: To test the hypothesis that risk factors related to lifetime estrogen exposure predict breast cancer incidence and to test if any subgroups experience enhanced benefit from raloxifene. PATIENTS AND METHODS: Postmenopausal women with osteoporosis (N = 7,705), enrolled onto the Multiple Outcomes of Raloxifene Evaluation (MORE) trial, were randomly assigned to receive placebo, raloxifene 60 mg/d, or raloxifene 120 mg/d for 4 years. Breast cancer risk was analyzed by the following baseline characteristics indicative of estrogen exposure: previous hormone replacement therapy, prevalent vertebral fractures, family history of breast cancer, estradiol level, bone mineral density (BMD), body mass index, and age at menopause. Therapy-by-subgroup interactions were assessed using a logistic regression model. RESULTS: Overall, women with the highest one-third estradiol levels (> or = 12 pmol/L) had a 2.07-fold increased invasive breast cancer risk compared with women with lower levels. Raloxifene significantly reduced breast cancer risk in both the low- and high-estrogen subgroups for all risk factors examined (P <.05 for each comparison). The women with the highest BMD and those with a family history of breast cancer experienced a significantly greater therapy benefit with raloxifene, compared with the two thirds of patients with lower BMD or those without a family history, respectively; the subgroup-by-therapy interactions were significant (P =.005 and P =.015, respectively). CONCLUSION: The MORE trial confirms that increased lifetime estrogen exposure increases breast cancer risk. Raloxifene therapy reduces breast cancer risk in postmenopausal osteoporotic women regardless of lifetime estrogen exposure, but the reduction is greater in those with higher lifetime exposure to estrogen.

Continued breast cancer risk reduction in postmenopausal women treated with raloxifene: 4-year results from the MORE trial. Multiple outcomes of raloxifene evaluation.

Raloxifene, a selective estrogen receptor modulator approved for the prevention and treatment of postmenopausal osteoporosis, has shown a significant reduction in breast cancer incidence after 3 years in this placebo-controlled, randomized clinical trial in postmenopausal women with osteoporosis. This article includes results from an additional annual mammogram at 4 years and represents 3,004 additional patient-years of follow-up in this trial. Breast cancers were ascertained through annual screening mammograms and adjudicated by an independent oncology review board. A total of 7,705 women were enrolled in the 4-year trial; 2,576 received placebo, 2,557 raloxifene 60 mg/day, and 2,572 raloxifene 120 mg/day. Women were a mean of 66.5-years old at trial entry, 19 years postmenopause, and osteoporotic (low bone mineral density and/or prevalent vertebral fractures). As of 1 November 1999, 61 invasive breast cancers had been reported and were confirmed by the adjudication board, resulting in a 72% risk reduction with raloxifene (relative risk (RR) 0.28, 95% confidence interval (CI) 0.17, 0.46). These data indicate that 93 osteoporotic women would need to be treated with raloxifene for 4 years to prevent one case of invasive breast cancer. Raloxifene reduced the risk of estrogen receptor-positive invasive breast cancer by 84% (RR 0.16, 95% CI 0.09, 0.30). Raloxifene was generally safe and well-tolerated, however, thromboembolic disease occurred more frequently with raloxifene compared with placebo (p=0.003). We conclude that raloxifene continues to reduce the risk of breast cancer in women with osteoporosis after 4 years of treatment, through prevention of new cancers or suppression of subclinical tumors, or both. Additional randomized clinical trials continue to evaluate this effect in postmenopausal women with osteoporosis, at risk for cardiovascular disease, and at high risk for breast cancer.

Digitized mammography: a clinical trial of postmenopausal women randomly assigned to receive raloxifene, estrogen, or placebo.

BACKGROUND: High mammographic density is associated with increased breast cancer risk. Previous studies have shown that estrogens increase breast density on mammograms, but the effect on mammographic density of selective estrogen receptor modulators, such as raloxifene, is unknown. We assessed changes in mammographic density among women receiving placebo, raloxifene, or conjugated equine estrogens in an osteoporosis prevention trial. METHODS: In a 5-year multicenter, double-blind, randomized, placebo-controlled osteoporosis prevention trial, healthy postmenopausal women who had undergone hysterectomy less than 15 years before the study and had no history of breast cancer received placebo, raloxifene (at one of two doses), or conjugated estrogens (ERT). Women from English-speaking investigative sites who had baseline and 2-year craniocaudal mammograms with comparable positioning (n = 168) were eligible for this analysis. Changes in mammographic density were determined by digital scanning and computer-assisted segmentation of mammograms and were analyzed with the use of analysis of variance. All statistical tests were two-sided. RESULTS: Among the four treatment groups after 2 years on study, the mean breast density (craniocaudal view) was statistically significantly greater in the ERT group than it was in the other three groups (P<0.01 for all three comparisons). Within treatment groups, the mean breast density from baseline to 2 years decreased statistically significantly in women receiving the placebo or either the higher or lower raloxifene dose (P = 0.003, P = 0.002, and P<0.001, respectively) and showed a nonstatistically significant increase in women receiving ERT. CONCLUSIONS: In an osteoporosis prevention trial, raloxifene did not increase breast density after 2 years of treatment. Raloxifene administration should not interfere with, and could even enhance, mammographic detection of new breast cancers.

Adaptive calibration scheme for quantification of nutrients and byproducts in insect cell bioreactors by near-infrared spectroscopy.

Spectroscopic methods are gaining in popularity in biotechnology because of their ability to deliver rapid, noninvasive measurements of the concentrations of multiple chemical species. Such measurements are particularly necessary for the implementation of control schemes for cell culture bioreactors. One of the major challenges to the development of spectroscopic methods for bioreactor monitoring is the generation of accurate and robust calibration models, particularly because of the inherent variability of biological processes. We have evaluated several methods of building calibration models, including synthetic calibrations and medium spiking methods. The approach that consistently produced reliable models incorporated samples removed from a bioreactor that were subsequently altered so as to increase the sample variation. Several large volume samples were removed from a bioreactor at varying time points and divided into multiple aliquots to which were added random, known amounts of the analytes of interest. Near-infrared spectra of these samples were collected and used to build calibration models. Such models were used to quantify analyte concentrations from independent samples removed from a second bioreactor. Prediction errors for alanine, glucose, glutamine, and leucine were 1.4, 1.0, 1.1, and 0.31 mM, respectively. This adaptive calibration method produces models with less error and less bias than observed with other calibration methods. Somewhat more accurate measurements could be attained with calibrations consisting of a combination of synthetic samples and spiked medium samples, but with an increase in calibration development time.

Increased protein productivity from immobilized recombinant yeast.

The Saccharomyces cerevisiae strain Mc16/p520 has an unstable plasmid, p520, which directs production of a wheat alpha-amylase. The effects of immobilizing this microorganism on the plasmid stability and the specific productivity of the secreted alpha-amylase were investigated. Small gelatin beads were used as the support in both fluidized and packed bed configurations, and the yeast cells were attached by covalent cross-linking with glutaraldehyde. These data were then compared to those for nonimmobilized, suspension cells.Plasmid stability was increased for the immobilized cells during continuous culture at dilution rates both above and below washout. Continuous suspension cultures were not stable and rapidly lost the plasmid. Immobilization caused an increase in specific and volumetric productivity during continuous culture, with a packed bed design resulting in the highest specific productivity.

Flameless atomic absorption (FAA) and gas-liquid chromatographic studies in arsenic bioanalysis.

Procedures for assessment of arsenic in soft tissue by use of flameless atomic absorption (FAA) and gas-liquid chromatography (GLC), have been evolved, with special emphasis on the analytical distinction among inorganic, monomethyl-, and dimethylarsenic in several oxidation states. The chemical bases for such speciation reside in several properties of the arsenicals under consideration: (1) pentavalent inorganic arsenic, methylarsonic, and cacodylic acid are not extracted from tissue matter made strongly acid with hydrochloric acid, while the corresponding trivalent forms (as halides) are extracted; (2) chloroform extracts of samples treated under reducing conditions (HCl-KI) retain organoarsenicals when these extracts are re-extracted with water, but do not when aqueous solutions of oxidants are employed; (3) reduced cacodylate (dimethylarsinous acid) is not detected in the graphite furnace of an FAA unit under conditions selected, while cacodylate can be so detected. For GLC studies, monomethyl- and dimethylarsenic are simultaneously measured as the diethyldithiocarbamate complexes with an instrument equipped for electron-capture detection and containing a glass column packed with silanized 5% OV-17 on Anakrom A.S.