Gut Microbiome, Adverse Effects, and Markers Through MEtabolic Reprogramming

This study examines how gut bacteria (the microbiome) change during breast cancer chemotherapy and whether these changes are linked to side effects, metabolism, and treatment response. Participants will provide stool samples and follow dietary guidance during treatment. **You may be eligible if...** - You have confirmed Stage I–III invasive breast cancer - You are scheduled to receive standard neoadjuvant or adjuvant chemotherapy (ddAC or TC regimen) - You have a BMI of at least 19.5 - You are willing to modify your diet and provide 3 stool samples during the study **You may NOT be eligible if...** - You have diabetes - You have a history of an eating disorder - You have serious uncontrolled conditions (e.g., kidney failure, liver cirrhosis) - You are pregnant or nursing - You take certain medications that require food (listed in the study) Talk to your doctor to see if this trial is right for you.