5-strain Probiotic Formulation in HR-positive Breast Cancer Receiving Aromatase Inhibitor to Prevent Bone Loss

This study is testing whether taking a 5-strain probiotic supplement can help prevent bone loss in women with hormone receptor-positive breast cancer who are starting aromatase inhibitor therapy. Aromatase inhibitors lower estrogen levels, which can weaken bones over time. The study explores whether improving gut bacteria can protect bone density during this treatment. **You may be eligible if...** - You are a woman 18 or older - You have been diagnosed with hormone receptor-positive breast cancer, stage 0–3, confirmed by biopsy - You are about to start taking an aromatase inhibitor (letrozole, anastrozole, or exemestane), with or without ovarian function suppression - Your blood counts and kidney function meet the required levels **You may NOT be eligible if...** - You have already started aromatase inhibitor therapy - You have already lost significant bone density (osteoporosis with a T-score below a certain threshold) - You are taking bone-strengthening medications (bisphosphonates or denosumab) - You have immune conditions or recent serious infections that make probiotics unsafe - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.