The goal of this observational study is to examine how frequently changes in taste occur in people with early-stage breast cancer who receive chemotherapy. It will also look at how these taste changes affect nutrition and quality of life. The main questions this study aims to answer are:

• How many participants develop changes in taste during chemotherapy?
• How do these changes affect eating habits, nutrition, and daily life?

Participants are women with non-metastatic breast cancer who are receiving chemotherapy before or after surgery.

Researchers will use standardized taste tests to measure how well participants can perceive different flavors. These tests are designed to provide accurate and reproducible results.

Participants will:

• Take part in taste tests during their chemotherapy treatment
• Have their nutritional status evaluated
• Answer questions about their quality of life

Dysgeusia, defined as an altered perception of taste, is a frequent but understudied adverse effect of several chemotherapy regimens used for the treatment of breast cancer. Taste alterations may arise from direct cytotoxic effects on taste receptor cells, changes in saliva composition, mucosal inflammation, altered signal transduction, or central nervous system effects. These disturbances can lead to reduced food enjoyment, alterations in dietary patterns, and potential deterioration of nutritional and functional status.

Although dysgeusia is commonly reported in clinical practice, estimates of its prevalence vary widely due to heterogeneous methodologies and the predominant reliance on self-reported symptoms rather than standardized sensory testing. Studies that objectively quantify changes in taste recognition thresholds during chemotherapy are limited, and little is known about specific aspects such as umami perception or chemesthetic sensitivity. Furthermore, factors that may predispose individual patients to developing dysgeusia-such as baseline taster status, nutritional condition, or specific treatment characteristics-remain poorly characterized.

This observational pilot study was designed to provide objective, reproducible data on taste function in patients with non-metastatic breast cancer receiving standard neoadjuvant or adjuvant chemotherapy. A combination of validated sensory tools, including taste strips and chemesthetic tests, is used to measure changes in taste perception over the course of treatment. Standardized methods were selected to ensure high sensitivity and repeatability and to allow quantitative comparison across different time points.

The study also integrates nutritional assessment and quality-of-life evaluation to explore the broader clinical implications of dysgeusia. Particular attention is given to potential associations between objective taste alterations, patient-reported symptoms, and parameters such as nutritional status, dietary intake, and functional well-being. Given the scarcity of comprehensive, methodologically rigorous studies in this area, the data generated may help clarify the clinical burden of dysgeusia and inform strategies to mitigate its impact on patients undergoing chemotherapy for breast cancer.

Inclusion Criteria:

• Age ≥ 18 years
• Diagnosis of non-metastatic breast cancer
• Indication for neoadjuvant or adjuvant chemotherapy as part of standard clinical practice
• Chemotherapy-naïve patients (no chemotherapy received in the previous 12 months)
• Signed written informed consent

Exclusion Criteria:

• Terminal or metastatic disease
• Pre-existing taste or smell disorders (e.g., anosmia, dysgeusia, neurological syndromes, etc.)
• Known allergies to any substances used in taste and chemesthetic function tests (e.g., quinine dihydrochloride, monosodium L-glutamate, capsaicin, etc.)
• Receiving neoadjuvant or adjuvant chemotherapy within research protocols
• Lack of signed written informed consent

This group includes male and female participants diagnosed with non-metastatic breast cancer who are receiving neoadjuvant or adjuvant chemotherapy according to standard clinical practice. Participants are treated at the Oncology Unit of Michele and Pietro Ferrero Hospital in Verduno. Eligible participants are those for whom chemotherapy is indicated as part of their routine care, and who are willing and able to complete sensory tests, nutritional assessments, and quality of life questionnaires during the study period.