Trial reportBreast cancer research and treatment2023
Effects of letrozole on serum estradiol and estrone in postmenopausal breast cancer patients and tolerability of treatment: a prospective trial using a highly sensitive LC-MS/MS (liquid chromatography-tandem mass spectrometry) method for estrogen measurement.
Trial report in Breast cancer research and treatment, 2023. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 7 papers, 1 of them a synthesis that pooled it.
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
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Who cites it
7 citing papers in PubMed, 1 synthesis or guideline pooled it, 3 citations in OpenAlex.
- Measuring serum oestrogen levels in breast cancer survivors using vaginal oestrogens: a systematic review.Breast cancer research and treatment · 2024Pooled it
- Menopause following cancer treatment-induced menopause: unique considerations and current recommendations.Reproduction & fertility · 2026Review
- Oncofertility in the Age of HER2 Blockade, Immunotherapy, PARP inhibitors, CDK4/6 inhibitors and Endocrine Treatment: Unanswered Questions in Breast Cancer.Current treatment options in oncology · 2026Review
- Sexual health among patients with breast cancer undergoing endocrine therapy: an integrative review.Supportive care in cancer : official journal of the Multinational Association of Supportive Care in Cancer · 2026Review
- Pharmacokinetic analysis of 25 mg estradiol subcutaneous bioabsorbable implant in postmenopausal women (CLARA STUDY).Menopause (New York, N.Y.) · 2026Article
- Effects of vaginal estrogen on serum estradiol during aromatase inhibitor therapy in breast cancer patients with vulvovaginal atrophy: a prospective trial.Breast cancer research and treatment · 2025Article
- Electroacupuncture Versus Auricular Acupressure Versus WaitliSt Control for Endocrine Therapy-Related Joint Pain in Patients With Breast Cancer (EASE): Study Protocol for a Pragmatic Multicenter Randomised Controlled Trial.Integrative cancer therapiesArticle
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
8 authors at 2 institutions in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
purposeTo analyze serum estradiol (E2) and estrone (E1) during letrozole treatment and their association to Quality of Life (QoL) and side-effects.
methodsPostmenopausal breast cancer patients starting adjuvant letrozole were eligible. Serum samples were taken at baseline, three, and 12 months. E2 and FSH were measured with routine chemiluminescent immunoassays. E2 and E1 were analyzed after trial completion with a highly sensitive liquid chromatography-tandem mass spectrometry method (LC-MS/MS) with lower limits of quantification (LLOQ) of 5 pmol/L. QoL was measured at baseline and at 12 months with the EORTC QLQ-C30 and QLQ-BR23 and the Women's Health questionnaires, and menopause-related symptoms with the modified Kupperman Index.
resultsOf 100 screened patients 90 completed the trial. Baseline mean LC-MS/MS E2 and E1 were 12 pmol/L (range < 5-57) and 66 pmol/L (< 5-226), respectively. E2 levels measured by immunoassay and LC-MS/MS showed no correlation. E2 and E1 were completely suppressed by letrozole except for one occasion (E1 11 pmol/L at 3 months). Pain, side effects of systemic therapy, vasomotor symptoms, joint and muscle aches, and vaginal dryness increased during letrozole treatment. A high baseline E2 was significantly associated with increased aching joints and muscles, but not with the other side effects.
conclusionsLetrozole supresses E2 and E1 completely below the LLOQ of the LC-MS/MS in postmenopausal women. High pre-treatment E2 levels were associated with more joint and muscle pain during letrozole. Automated immunoassays are unsuitable for E2 monitoring during letrozole therapy due to poor sensitivity.
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