This prospective observational study aims to investigate the relationship between sarcopenia and the development of paclitaxel-induced peripheral neuropathy in patients with early-stage breast cancer. The study was conducted between November 1, 2024, and May 6, 2025, across three oncology centers in Turkey. Skeletal muscle index (SMI) was calculated using pre-treatment computed tomography (CT) scans at the third lumbar vertebra (L3) level. Neuropathy assessment was performed using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire - Chemotherapy-Induced Peripheral Neuropathy 20-item scale (EORTC QLQ-CIPN20) before and after paclitaxel treatment. Patients reporting neuropathy symptoms were referred for electromyography (EMG) to confirm diagnosis, and neuropathy was graded according to the Common Terminology Criteria for Adverse Events version 4.0 (CTCAE v4.0). The association between baseline sarcopenia and both the incidence and severity of neuropathy was analyzed. The findings may help identify patients at higher risk of neurotoxicity from paclitaxel-based chemotherapy.

This multicenter prospective observational study was designed to evaluate whether baseline sarcopenia is associated with the development and severity of peripheral neuropathy in patients receiving paclitaxel as part of neoadjuvant or adjuvant chemotherapy for early-stage breast cancer.

Patients aged 18 years or older with histologically confirmed early-stage breast cancer who received paclitaxel-based treatment (including combinations with carboplatin, trastuzumab, or pertuzumab) were included. Skeletal muscle index (SMI) was calculated from computed tomography (CT) scans at the third lumbar vertebra (L3) level, taken prior to paclitaxel initiation.

Neuropathy was assessed at baseline and after the final paclitaxel cycle using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire - Chemotherapy-Induced Peripheral Neuropathy 20-item scale (EORTC QLQ-CIPN20). Patients with symptoms suggestive of neuropathy were referred for electromyography (EMG) confirmation, and neuropathy severity was classified according to the Common Terminology Criteria for Adverse Events version 4.0 (CTCAE v4.0).

The primary aim was to evaluate the association between sarcopenia and the occurrence of chemotherapy-induced peripheral neuropathy (CIPN). Secondary outcomes included the relationship between sarcopenia and the severity grade of neuropathy.

This study seeks to provide insights into risk stratification for CIPN and guide supportive care strategies in early-stage breast cancer patients undergoing taxane-based chemotherapy.

Inclusion Criteria:

• Age ≥ 18 years
• Histologically confirmed early-stage breast cancer
• Planned to receive neoadjuvant or adjuvant paclitaxel-based chemotherapy
• Patients receiving paclitaxel-carboplatin or paclitaxel-trastuzumab-pertuzumab regimens are also eligible
• Provided written informed consent

Exclusion Criteria:

• Age < 18 years
• No pathological diagnosis of breast cancer
• Refusal to participate in the study
• Male patients

Only individuals who self-identify as women and have a biologically female sex assigned at birth are eligible to participate in this study due to the focus on early-stage breast cancer.

The study population consisted of adult female patients diagnosed with early-stage breast cancer and treated with neoadjuvant or adjuvant paclitaxel-based chemotherapy regimens at three oncology centers in Turkey. Patients were enrolled consecutively if they met the inclusion criteria and provided informed consent. Data were collected prospectively, including pre-treatment CT scans for muscle mass analysis and neuropathy assessments.

Individual participant data (IPD) will not be shared due to institutional policies and the absence of a data sharing infrastructure. The study involves sensitive clinical information, and no formal mechanism for anonymized data sharing is currently in place.