An observational study in Hormone Receptor-Positive Breast Cancer, sponsored by D'Or Institute for Research and Education. Not yet recruiting. Open to female participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-09-22.
Sponsored by D'Or Institute for Research and Education · Observational
his prospective observational study will evaluate whether body mass index (BMI) is associated with serum estradiol levels in premenopausal women with hormone receptor-positive breast cancer. Participants will already be receiving standard adjuvant treatment with an aromatase inhibitor and pharmacologic ovarian suppression as part of their routine clinical care. The study will not assign or modify cancer treatment.
Approximately 172 participants will be enrolled at multiple study sites in Brazil. They will be classified into two main groups: normal BMI and overweight or obesity. Clinical information, medication use, physical activity, weight, height, and serum estradiol levels will be recorded. Estradiol will be measured using an ultrasensitive laboratory method, with the main assessment occurring after approximately three months of treatment.
The primary objective is to compare the proportion of participants with serum estradiol levels above 2.72 pg/mL between the two BMI groups. The study will also examine the relationship between BMI and absolute estradiol levels and explore whether clinical characteristics, previous chemotherapy, physical activity, or use of glucagon-like peptide-1 receptor agonists are associated with inadequate estrogen suppression.
This is a multicenter, prospective, observational cohort study designed to evaluate the association between body mass index (BMI) and serum estradiol levels in premenopausal women with hormone receptor-positive invasive breast cancer receiving adjuvant endocrine therapy with an aromatase inhibitor combined with pharmacologic ovarian suppression using a gonadotropin-releasing hormone analog.
All endocrine treatments will be prescribed as part of routine clinical care. Participation in the study will not determine the selection, dose, schedule, continuation, or modification of anticancer treatment. No experimental intervention, treatment allocation, or randomization is planned.
Approximately 172 participants will be enrolled. For the primary analysis, participants will be classified according to World Health Organization BMI categories and grouped as having normal BMI or overweight/obesity. At enrollment, demographic, anthropometric, clinical, and oncologic information will be collected, including tumor characteristics, previous cancer treatment, type and timing of aromatase inhibitor and ovarian suppression therapy, concomitant medications, physical activity, and use of glucagon-like peptide-1 receptor agonists.
Weight and height will be measured to calculate BMI. Serum estradiol will be assessed using an ultrasensitive laboratory method. A baseline estradiol measurement may be obtained when applicable, depending on the timing of enrollment. The main estradiol assessment will be performed after approximately three months of combined aromatase inhibitor therapy and pharmacologic ovarian suppression, within a protocol-defined visit window of plus or minus 14 days. If a result suggests inadequate estrogen suppression, an additional measurement may be requested within 14 days using a different laboratory method, according to institutional practice and local availability.
The primary outcome is the proportion of participants with inadequate estrogen suppression, defined as a serum estradiol concentration greater than 2.72 pg/mL after approximately three months of treatment. This proportion will be compared between participants with normal BMI and those with overweight/obesity.
Secondary and exploratory analyses will evaluate absolute estradiol concentrations across BMI categories, the correlation between BMI and serum estradiol, a potential BMI cutoff associated with inadequate estrogen suppression, and clinical characteristics associated with inadequate suppression. Exploratory subgroup analyses will consider previous chemotherapy, physical activity, and use of glucagon-like peptide-1 receptor agonists.
The primary comparison will use a chi-square test or Fisher's exact test, as appropriate. Binary logistic regression will assess the association between BMI and inadequate estrogen suppression, with BMI evaluated as both a categorical and continuous variable and adjustment for clinically relevant potential confounders. Continuous outcomes will be analyzed using parametric or nonparametric methods according to their distributions. The relationship between BMI and estradiol concentration will also be assessed using Spearman correlation, and receiver operating characteristic curve analysis will be used to explore a potential BMI cutoff associated with inadequate estrogen suppression.
3,599 studies on the registry are indexed under Overweight; 852 are open to participants now.
This study's planned enrollment of 172 is above the median of 154 across 424 observational studies indexed under Overweight.
Browse Overweight studies →D'Or Institute for Research and Education is the lead sponsor of 42 studies on the registry; 13 are open to participants now.
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Premenopausal adult women with histologically confirmed hormone receptor-positive invasive breast cancer receiving adjuvant endocrine therapy with an aromatase inhibitor combined with pharmacologic ovarian suppression using a gonadotropin-releasing hormone analog. Potential participants will be identified during routine outpatient visits at participating oncology centers in Brazil. Participants will be classified according to World Health Organization body mass index categories and analyzed in two groups: normal body mass index and overweight or obesity.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Female sex. Age 18 years or older. confirmed hormone receptor-positive invasive breast cancer, defined as estrogen receptor-positive and/or progesterone receptor-positive disease, regardless of human epidermal growth factor receptor 2 status.
Premenopausal status at the initiation of ovarian suppression, as determined by menstrual history and/or laboratory criteria according to medical assessment.
Indication for treatment with an aromatase inhibitor (anastrozole, letrozole, or exemestane) combined with pharmacologic ovarian suppression using a gonadotropin-releasing hormone analog.
Continuous use of an aromatase inhibitor and a gonadotropin-releasing hormone analog for at least 3 months before the primary study assessment.
Documented at enrollment. Ability to understand the study information and provide written .
Exclusion Criteria:
status at the initiation of endocrine therapy. Known endocrine disorders that may interfere with the production or metabolism of sex .
Concomitant use of medications known to interfere with estradiol metabolism or measurement, including systemic corticosteroids at supraphysiologic doses.
disease at enrollment. Technical or logistical inability to undergo serum estradiol measurement using an ultrasensitive laboratory method.
Concurrent participation in another clinical study that may interfere with the hormonal outcomes evaluated in this study.
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).
Your pathology report is the document that shows this.
Neoadjuvant treatment is given before the main treatment (usually surgery), often to shrink a tumour. Adjuvant treatment is given after it, to lower the chance of the cancer coming back.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
Histologically or cytologically confirmed
The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).
Your pathology report is the document that shows this.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Adjuvant and neoadjuvant
Neoadjuvant treatment is given before the main treatment (usually surgery), often to shrink a tumour. Adjuvant treatment is given after it, to lower the chance of the cancer coming back.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Postmenopausal
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Metastases
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Premenopausal participants with hormone receptor-positive breast cancer receiving an aromatase inhibitor and pharmacologic ovarian suppression who have a body mass index within the normal range according to World Health Organization criteria.
Premenopausal participants with hormone receptor-positive breast cancer receiving an aromatase inhibitor and pharmacologic ovarian suppression who are classified as having overweight or obesity according to World Health Organization body mass index criteria.
Percentage of Participants With Inadequate Estrogen Suppression
Percentage of participants with a serum estradiol concentration greater than 2.72 pg/mL after approximately 3 months of treatment with an aromatase inhibitor and pharmacologic ovarian suppression. Serum estradiol will be measured using an ultrasensitive laboratory method. The percentage will be calculated as the number of participants with estradiol greater than 2.72 pg/mL divided by the number of evaluable participants in each body mass index group, multiplied by 100. Results will be compared between participants with normal body mass index and those with overweight or obesity.
Time frame: At 3 months of treatment (visit window: ±14 days)
Serum Estradiol Concentration by Body Mass Index Category
Serum estradiol concentration, measured in pg/mL using an ultrasensitive laboratory method, will be summarized and compared across body mass index categories.
Time frame: At 3 months of treatment (visit window: ±14 days)
Correlation Between Body Mass Index and Serum Estradiol Concentration
The relationship between body mass index, measured in kg/m², and serum estradiol concentration, measured in pg/mL, will be assessed using Spearman's correlation coefficient. The coefficient ranges from -1 to 1, with higher positive values indicating a stronger positive association.
Time frame: At 3 months of treatment (visit window: ±14 days)
Body Mass Index Cutoff Associated With Inadequate Estrogen Suppression
A potential body mass index cutoff, measured in kg/m², associated with serum estradiol greater than 2.72 pg/mL will be explored using receiver operating characteristic curve analysis. The analysis will include estimation of the area under the curve, sensitivity, and specificity of the identified cutoff.
Time frame: At 3 months of treatment (visit window: ±14 days)
Association Between Clinical Characteristics and Inadequate Estrogen Suppression
Associations between prespecified clinical characteristics and inadequate estrogen suppression, defined as serum estradiol greater than 2.72 pg/mL, will be evaluated using binary logistic regression. Results will be reported as odds ratios with 95% confidence intervals. Evaluated characteristics may include body mass index, age, previous chemotherapy, endocrine treatment characteristics, concomitant medications, and other clinically relevant potential confounders collected according to the protocol.
Time frame: At 3 months of treatment (visit window: ±14 days)
Serum Estradiol Outcomes in Prespecified Clinical Subgroups
Serum estradiol concentration and the percentage of participants with estradiol greater than 2.72 pg/mL will be explored in subgroups defined by previous chemotherapy, physical activity, and use of glucagon-like peptide-1 receptor agonists. These analyses are exploratory.
Time frame: At 3 months of treatment (visit window: ±14 days)
No study locations are listed for this record.
Plan to share: No — Individual participant data will not be made publicly available under the current protocol because the informed consent and data governance procedures do not provide for external sharing of individual-level clinical and laboratory data. Study findings will be disseminated in aggregate form to protect participant privacy and confidentiality and to comply with applicable ethical requirements and Brazilian data protection legislation.
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D'Or Institute for Research and Education