Endocrine therapy is the mainstay of adjuvant therapy in premenopausal women with hormone receptive-positive (HR+) breast cancer as it has been demonstrated that it reduces long-term recurrences and increases survivial. However, this therapy, which suppresses estrogen production and estrogen-induced effects, is associated with the development of joint pain which can significantly reduce quality of life and lead to treatment discontinuation.

The main question the study aims o answer is:

Can balneotherapy (BT) alleviate muscle-skeletal pain (primary objective) derived from endocrine therapy and improve quality of life (secondary objective) in young women with HR+ breast cancer?

PATIENTS AND METHODS

Inclusion Criteria:

• Premenopausal women diagnosed with early-stage hormonal receptor (HR+) breast cancer (stages I-III) undergoing ovarian suppression and aromatase inhibitor therapy (i.e., endocrine therapy) for at least three months.
• Reported musculoskeletal pain (VAS score ≥2) associated with the initiation of the endocrine therapy.

Exclusion Criteria:

• Chronic musculo-skeletal conditions predating the initiation of endocrine therapy.
• Anxiety-depression syndrome predating the initiation of endocrine therapy that is pharmacologically treated.
• Fear of water
• Fecal and urinary incontinence
• Severe venous insufficiency
• Epilepsy
• Physical disabilities that may hinder the performance of BT/aquatic exercises

Participants will be recruited in Hospital del Mar's Oncology department and in the hospital's Mineral Metabolism Clinic (Internal Medicine Department).

In addition, Caldes de Montbui's City Council will also advertise the project for patient recruitment on its public website.

Patient selection and recruitment will be performed by the study's investigators at the Hospital del Mar Research Institute.

STUDY DESIGN Prospective randomized controlled study.

STUDY FLOW Eligible particpants will undergo an initial visit (baseline) in which clinical data will be reviewed and registered. Forty-eight participants will be randomly assigned to the BT group and 48 to the control group through a lottery method. At this time point, participants will be asked to answer/complete the following scales/questionnaires: visual analog scale for pain (VAS), the SF-36 quality of life test, the Hospital Anxiety and Depression Scale (HADS), and the Pittsburgh Sleep Quality Index (PSQI). These tools measure pain severity (primary objective), quality of life, levels of anxiety and depression, and sleep quality, respectively. All results will be recorded in an anonymized database managed by the Hospital del Mar Research Institute.

Treatment Program: Participants allocated to BT group will undergo 12 sessions over four weeks (3 weekly sessions) involving thermal water exercises at 32°C (10 min inhalation, 10 min warm-up, 20 min specific exercises, 10 min relaxation), thermal showers (7 min jet or circular showers), and 30 minutes rest. Participants in the control group will be asked to not initiate new physical therapies and to continue with their usual care.

At the end of the BT program (or 4 weeks after baseline for the participants allocated to the control group), participants will be asked to answer/complete the same questionnaires/scales they did at baseline (second timepoint).

All participants will be asked to answer again the same questionnaries 6 months after BT completion or 7 months after baseline in the case of the participants of the control group (third timepoint).

Study outcomes will be obtained by calculating the differences in scores for the study variables (VAS (primary objective), SF-36, PSQI, and HADS (secondary objectives) between the end of BT and baseline, and the third timepoint vs baseline. Outcome analysis will be conducted by a qualified professional who is blinded to the two groups (BT group and control group).

In addition, the following data will be collected at baseline for each patient and included in the database for the study: age (years), Body Mass Index (BMI) (kg/m2), current medications, and time since the initiation of adjuvant endocrine therapy (months).

These data will be used as study variables and for adjustment in the multivariable analysis. The database and analyses will be managed by the principal investigator.

Data will be analyzed using descriptive statistics for qualitative variables and parametric or non-parametric tests for continuous variables. Changes in pain, quality of life, and emotional scores will be evaluated using linear models, with adjustments for confounders. Statistical significance will be set at α = 0.05.

Adverse events will be registered throughout the duration of the study. If participants allocated to the BT group report significant adverse effects directly associated with BT, they will discontinue the therapy.

Inclusion Criteria:

Premenopausal women diagnosed with early-stage hormonal receptor (HR+) breast cancer (stages I-III) undergoing ovarian suppression and aromatase inhibitor therapy (i.e., endocrine therapy) for at least three months.

- Reported musculoskeletal pain (VAS score ≥2) associated with the initiation of the endocrine therapy.

Exclusion Criteria

• Chronic musculoskeletal conditions predating the initiation of endocrine therapy and/or unrelated to effects derived from the endocrine therapy (i.e. fibromyalgia)
• Anxiety-depression syndrome predating the initiation of endocrine therapy that is treated with drugs.
• Fear of water
• Fecal and/or urinary incontinence
• Severe venous insufficiency
• Epilepsy and physical disabilities that may hinder the performance of Balneotherapy (BT)/aquatic exercises.

This study is focused on endogen estrogenic suppression in premenopausal women so biological women are the only eligible candidates for this study.