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Optimal care for breast cancer patients undergoing aromatase inhibitor (AI) treatment is ensured when estradiol (E2) levels are adequately suppressed. To assess treatment efficacy accurately, it is important to measure the serum E2 levels using a well validated assay method with high sensitivity and specificity. This translates into the urgent need to evaluate various E2 immunoassay kits, which are frequently used in hospital settings to measure E2 serum levels in patients undergoing AI treatment, so clinicians obtain accurate and reliable measurements allowing appropriate clinical decision making. Our objective was to evaluate the performance of different commercially available and commonly used E2 immunoassay kits regarding measurement of E2 levels in the serum of postmenopausal breast cancer patients treated with AIs, in comparison to a highly accurate and reliable mass spectrometry assay. Clinical and demographic data were obtained from 77 postmenopausal breast cancer patients who were treated with an AI. Serum E2 levels were measured by 6 immunoassay methods and by liquid chromatography-tandem mass spectrometry (LC-MS/MS), which served as the standard for comparison. Analysis of E2 by LC-MS/MS showed that 70% of the samples had levels that were <5 pg/ml. Three of the assays carried out with commercial E2 immunoassay kits had poor sensitivities and were not able to detect E2 levels <10 or <20 pg/ml. Although two of the E2 assays using commercial kits demonstrated a better sensitivity (5 pg/ml), the measured E2 values were substantially higher than those obtained by LC-MS/MS. The assay with the sixth commercial E2 kit grossly underestimated the true E2 values. E2 assays carried out with commercial E2 immunoassay kits lack the accuracy to measure the very low serum E2 levels found in patients being treated with AIs. Serum samples from such patients should be sent to laboratories that use a mass spectrometry assay.

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BACKGROUND: Finasteride, an inhibitor of 5α-reductase (type II), lowers intraprostatic dihydrotestosterone (DHT), which is reflected in serum as reduced 5α-androstane-3α,17ß-diol glucuronide (3α-dG). It also modestly increases serum testosterone (T), estrone (E(1)), and estradiol (E(2)). In this altered hormonal milieu, it is unknown whether serum concentrations of these hormones are associated with prostate cancer risk. METHODS: In this nested case-control study of men in the finasteride arm of the Prostate Cancer Prevention Trial, sex steroid hormones and sex hormone binding globulin were measured at baseline and approximately 3-year posttreatment in 553 prostate cancer cases and 694 controls. RESULTS: Median posttreatment changes in concentrations of 3α-dG, T, E(1), and E(2) were -73.8%, +10.1%, +11.2%, and +7.5% (all P < 0.001), respectively. Neither the pre- nor posttreatment concentrations of 3α-dG, nor its change, were associated with risk. Pretreatment, high concentrations of E(1) and low concentrations of T were associated with increased cancer risk [OR; 95% confidence interval (CI) quartile 4 vs. 1: 1.38 (0.99-1.93) P(trend) = 0.03; 0.64 (0.43-0.93) P(trend) = 0.07, respectively]. Posttreatment, high concentrations of both E(1) and E(2) were associated with increased cancer risk [OR; 95% CI quartile 4 vs. 1: 1.54 (1.09-2.17) P(trend) = 0.03; 1.49 (1.07-2.07) P(trend) = 0.02, respectively]. CONCLUSIONS: Among finasteride-treated men, concentrations of 3α-dG were not associated with total or Gleason grades 2 to 6, 7 to 10, or 8 to 10 cancer. High serum estrogens may increase cancer risk when intraprostatic DHT is pharmacologically lowered. IMPACT: Low posttreatment serum estrogens may identify men more likely to benefit from use of finasteride to prevent prostate cancer.

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Oocyte donors have high serum estradiol (E2) levels similar to the serum levels seen in the first trimester of pregnancy. We report in this article our studies comparing cell proliferation, Ki67 (MIB1), and estrogen and progesterone receptor levels (ERα, PRA, and PRB) in the breast terminal duct lobular units of oocyte donors, women in early pregnancy, and in normally cycling women. Breast tissue and blood samples were obtained from 10 oocyte donors, and 30 pregnant women at 5-18 weeks of gestation. Breast tissue samples were also obtained from 26 normally cycling women. In the oocyte donors: peak E2 (mean ~15,300 pmol/l) was reached on the day before oocyte (and tissue) donation; peak progesterone (P4; mean 36.3 nmol/l) was reached on the day of donation; Ki67 was positively associated with level of E2, and the mean Ki67 was 7.0% significantly greater than the mean 1.8% of cycling women. In the pregnant women: mean E2 rose from ~2,000 pmol/l at 5 weeks of gestation to ~27,000 pmol/l at 18 weeks; mean P4 did not change from ~40 nmol/l until around gestational week 11 when it increased to ~80 nmol/l; mean Ki67 was 15.4% and did not vary with gestational age or E2. Oocyte donors have greatly increased levels of E2 and of breast-cell proliferation, both comparable in the majority of donors to the levels seen in the first trimester of pregnancy. Whether their short durations of greatly increased E2 levels are associated with any long-term beneficial effects on the breast, as occurring in rodent models, is not known.

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IGF-1 levels increased, and IGF-2 and IGFBP-3 levels remained unchanged, in postmenopausal women following oophorectomy. The increase in IGF-1 likely results from decreased ovarian steroidogenic precursors resulting from removal of the hormonally active ovary. This finding raises concerns, given the association between increased IGF-1 and elevated colon cancer risk, and adds to the literature suggesting a potential benefit from ovarian preservation.

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