Impact of Neoadjuvant Chemotherapy Administration Time of Day on Pathological Response in Patients with Early Triple-Negative Breast Cancer.

May 4, 2026Cancers

Time of Day for Pre-Surgery Chemotherapy and Tumor Response in Early Triple-Negative Breast Cancer

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Abstract

The pathological complete response (pCR) rate in patients with triple-negative breast cancer treated with neoadjuvant chemotherapy was 48.9%.

The study involved 94 patients with a median age of 51 years who received chemotherapy in a day hospital setting.
Chemotherapy infusion times were recorded, with treatments administered between 9:00 and 17:40.
No significant differences were found in clinical outcomes between patients receiving early versus late infusions.
The analysis included various time of day cut-offs but did not show an association with histological response or event-free survival.
Findings indicate that further investigation into chronotherapy for breast cancer may be warranted despite the study's limitations.

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Triple-negative breast cancer (TNBC) is associated with poor prognosis, highlighting the need for innovative therapeutic strategies. Chronomodulated chemotherapy yielded improved efficacy and tolerability in several malignancies; however, evidence in breast cancer remains limited. This study investigated the association between the time of day of administration (ToDA) of neoadjuvant chemotherapy (NAC) and clinical outcomes in patients with TNBC treated in a day hospital setting.This retrospective cohort included patients treated at Saint-Louis Hospital with neoadjuvant dose-dense, dose-intense cyclophosphamide-epirubicin followed by weekly paclitaxel. Infusion start times of each chemotherapy agent were systematically recorded. The primary endpoint was pathological complete response (pCR; Residual Cancer Burden [RCB] = 0). Secondary endpoints included RCB classes, early metabolic response, treatment tolerance, and 36-month event-free survival (EFS). Patients were classified into early or late infusion groups using multiple ToDA cut-offs, and cosine-based analyses were performed.Ninety-four patients (median age 51 years) received NAC between 9:00 and 17:40 which aligns with the day hospital unit's opening hours. With a median follow-up of 39.9 months, the pCR rate was 48.9%. No significant differences were observed between early and late infusion groups for any endpoint, regardless of ToDA cut-off or analytical approach.This first chronotherapeutic study in patients with early TNBC showed no association between ToDA of NAC administered between 9:00 and 17:40 and histological response or EFS. Although limited by sample size and the restricted infusion time window, our study provides novel data and methodological insights supporting further investigation of chronotherapy in patients with breast cancer. Background: Methods: Results: Conclusions:

Impact of Neoadjuvant Chemotherapy Administration Time of Day on Pathological Response in Patients with Early Triple-Negative Breast Cancer.

Abstract

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