Objectives: Identify the main changes in the health-related quality of life (HRQoL) of women diagnosed with breast cancer (BC) undergoing chemotherapy.

Methods: Prospective cohort study that included 33 women diagnosed with clinical stages I–III BC and who underwent adjuvant chemotherapy. HRQoL was assessed using the EORTC QLQ-C30 and EORTC QLQ-BR23 instruments 1 week before the start of chemotherapy and during the third month of chemotherapy.

Results: There was a decline in the HRQoL scores of patients during treatment. Therefore, chemotherapy alters the patient’s perceptions of their HRQoL since there is a decrease in global health status/quality of life (QoL) and functional scales such as physical functioning, role functioning, emotional functioning, social functioning, body image, sexual function and sexual enjoyment. We also observed an increase in side effects related to the systemic therapy, fatigue, nausea and vomiting, insomnia, appetite loss and diarrhoea, despite a decrease in breast symptoms and arm symptoms.

Conclusions: HRQoL was negatively affected during chemotherapy. Even though HRQoL assessment is a useful method for optimising patients’ care, its implementation into clinical practice remains a challenge. Since side effects are very often underestimated, we consider that the evaluation of HRQoL parameters should be done for BC patients treated with chemotherapy.