Effect of a Brassicaceae-Enriched Diet on Menopausal Symptoms in Women With Breast Cancer Receiving Antiestrogen Therapy

Breast cancer treatment in women of childbearing age may require antiestrogen therapy, which can result in iatrogenic menopause. Vasomotor symptoms, particularly hot flashes and night sweats, are among the most common symptoms of this condition and may substantially affect patients' quality of life. The sudden reduction in estrogen levels may also be associated with increased cardiovascular risk and alterations in bone formation and resorption, potentially contributing to osteopenia and osteoporosis.

Nutritional interventions are of particular interest in breast cancer survivors. Vegetables belonging to the Brassicaceae family are rich in micronutrients, vitamins, fiber, folates, glucosinolates, and other bioactive compounds. Glucosinolates are converted into isothiocyanates through the action of myrosinase or the intestinal microbiota. Isothiocyanates have been shown to release hydrogen sulfide (H2S) in the presence of organic thiols, suggesting that some of the potential beneficial effects associated with glucosinolate-rich vegetables may involve the H2S pathway.

Brassicaceae vegetables also contain compounds, including thiocyanates and goitrin, that may potentially affect thyroid function. However, available preclinical and clinical evidence indicates that the amounts generally consumed as part of the diet are not expected to reach levels associated with clinically relevant thyroid toxicity. Thyroid-related conditions are therefore considered in the eligibility criteria of the study.

The BRASSICA study is a randomized, controlled, parallel-group nutritional intervention study designed to evaluate the effect of increasing the dietary intake of Brassicaceae vegetables on menopausal symptoms in women with histologically confirmed hormone-sensitive breast cancer receiving adjuvant antiestrogen therapy. Participants are randomized in a 1:1 ratio, with stratification according to age, to either a nutritional intervention group or a control group. Randomization is performed by the oncologist.

The primary objective is to evaluate whether the inclusion of at least five servings per week of vegetables belonging to the Brassicaceae family can improve vasomotor menopausal symptoms, particularly hot flashes, compared with a control group receiving no specific dietary advice regarding Brassicaceae intake. Secondary objectives include the evaluation of other menopausal symptoms and cardiovascular and osteopenic risk factors.

Participants assigned to the intervention group receive nutritional advice to include at least five servings per week of Brassicaceae vegetables in their usual diet. Examples include cabbage, Brussels sprouts, broccoli, mustard, radishes, daikon, horseradish, and watercress. One serving corresponds to approximately 200 grams of vegetables. Participants are free to choose the type of Brassicaceae vegetable and when to consume it. This intervention does not consist of a prescribed diet but rather specific dietary advice aimed at increasing Brassicaceae consumption. Participants assigned to the control group undergo a standard nutritional assessment without receiving specific advice to increase Brassicaceae intake.

Eligible participants are women aged 18 to 60 years with histologically confirmed hormone-sensitive breast cancer who have been receiving adjuvant antiestrogen therapy, including tamoxifen, an LH-RH analogue, or an aromatase inhibitor, for at least 6 months before enrollment. Participants must be willing to continue hormone therapy for the duration of the study and must have spontaneous or induced amenorrhea. Participants are required to have at least six hot flashes per day or a score of at least 15 on the Greene Climacteric Scale (GCS) during the week before enrollment and a performance status of 1 or lower.

Major exclusion criteria include severe and pharmacologically uncontrolled depression, osteoporosis, hypercholesterolemia and/or hypertension; allergy or intolerance to Brassicaceae vegetables for participants assigned to the nutritional intervention; thyroid disorders; use of serotonin reuptake inhibitors, serotonin and norepinephrine reuptake inhibitors or anticonvulsants used for the management of vasomotor symptoms; and ongoing chemotherapy or radiotherapy. Withdrawal of informed consent is a criterion for discontinuation from the study.

At baseline, participants undergo clinical, nutritional, and laboratory assessments. Menopausal symptoms and quality of life are evaluated using questionnaires based on validated instruments, including the Menopause-Specific Quality of Life Questionnaire (MenQol) and the Greene Climacteric Scale (GCS).

During the first 6 months, assessments are performed at baseline and at 3 and 6 months in both study groups. Routine assessments include markers related to osteopenia/osteoporosis, such as alkaline phosphatase; cardiovascular risk parameters, including the total cholesterol/HDL ratio and blood pressure; inflammatory and endothelial dysfunction markers; and anthropometric parameters, including body weight, body mass index (BMI), and waist circumference.

Additional blood aliquots are collected during routine blood sampling at baseline and at 3 and 6 months. These samples are used for non-routine analyses including interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-alpha), and markers related to the H2S pathway, including the expression of cystathionine gamma-lyase (CSE) and cystathionine beta-synthase (CBS), plasma H2S levels, and protein sulfhydration, including sulfohemoglobin. Results of these non-routine analyses are not communicated to participants.

The primary endpoint is the change in vasomotor symptoms, specifically hot flashes and night sweats, assessed at baseline and at 3 and 6 months and compared between the intervention and control groups. Secondary endpoints include changes in somatic, psychological, and sexual menopausal symptoms, as well as markers of osteopenia/osteoporosis, cardiovascular risk, blood pressure, inflammatory markers, and endothelial dysfunction markers.

Following completion of the 6-month clinical and nutritional assessment period, participants enter a long-term follow-up phase with telephone assessments at 9, 12, and 18 months. During these telephone interviews, participants are asked about adherence to the nutritional advice received during the study and the long-term continuation of Brassicaceae consumption. General health and menopausal symptoms are also assessed, with particular attention to the persistence, recurrence, or resolution of vasomotor symptoms and their relationship with the participant's decision to continue following the nutritional advice.

Thus, the follow-up period for each participant lasts 18 months from the baseline assessment. The first 6 months include clinical, nutritional, and laboratory evaluations, whereas the 9-, 12-, and 18-month assessments consist of telephone interviews. After completion of the first 6 months, participants continue to be followed according to routine clinical practice. The overall duration of the study is estimated to be 4 years.

Biological samples are identified by a study-specific code and transferred from Oncology to the Pharmacology Laboratory of the Department of Pharmacy, University of Pisa. Samples are stored under the responsibility of the laboratory for the duration of the study. Study data are also managed using participant identification codes to protect participants' identity.

The planned sample size is 80 participants. The statistical calculation estimates that 34 participants per group are required for the primary endpoint, assuming an alpha error of 1% and 90% statistical power. Allowing for an estimated 10% dropout rate, the total planned enrollment is 80 participants.

Statistical analyses include two-tailed Student's t-tests for paired data and two-tailed Student's t-tests for independent samples.

The study is conducted in accordance with ethical principles and Good Clinical Practice. Written informed consent is obtained before participation. The study is sponsored by Azienda Ospedaliero-Universitaria Pisana (AOUP) and is conducted in collaboration with the Department of Pharmacy of the University of Pisa. Non-routine laboratory analyses are funded by the Department of Pharmacy, and no additional costs are expected for AOUP.