The following article features coverage from the NCCN 2022 Annual Conference. Click here to read more of Cancer Therapy Advisor’s conference coverage.

The timing of neoadjuvant chemotherapy administration in breast cancer may impact recurrence rates as well as treatment tolerability, according to research presented at the NCCN 2022 Annual Conference.

The study showed that patients who received most treatments after noon required fewer dose reductions and were less likely to stop treatment.

In addition, recurrence rates were highest among patients who received at least 70% of treatments before noon.

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“Early-stage breast cancer constitutes a potentially curable disease. The potential for curability, however, is compromised by dose reductions and discontinuations prompted by poor tolerance,” said Kristen Kelley, MD, of the Huntsman Cancer Institute in Salt Lake City, when presenting the study at the meeting. 

The study included 153 adults with stage I (16.34%), II (66.01%), or III (15.03%) breast cancer. Patients had hormone-receptor (HR)-positive/HER2-negative disease (32.03%), HR+/HER2+ disease (37.25%), or triple-negative disease (29.41%). Information on stage and receptor status was missing for some patients.

Patients received neoadjuvant chemotherapy at a single center between 2014 and 2020. Most received chemotherapy containing an anthracycline (68.63%).  

Patients were divided into 4 categories according to the timing of chemotherapy administration:

  • AM — Receiving at least 70% of treatments before noon (n=11)
  • PM — Receiving at least 70% of treatments after noon (n=81)
  • Mixed AM — Receiving 50% to 70% of treatments before noon (n=24)
  • Mixed PM — Receiving 50% to 70% of treatments after noon (n=37).

In a multivariate analysis, mixed AM patients had significantly more dose reductions than PM patients (odds ratio [OR], 4.47; 95% CI 1.60-12.48, P =.004).

Similarly, mixed AM patients had more early terminations of treatment than PM patients (OR, 3.23; 95% CI 0.96-10.82, P =.057).

Recurrence rates were highest in the AM chemotherapy group (27.2%), followed by the PM group (18.5%), the mixed PM group (8.1%), and the mixed AM group (0%; P =.043).

No significant differences were found between the 4 groups in terms of hospitalizations, treatment delays, and weight loss.

Because of the small number of patients in the AM group, the researchers conducted an additional analysis with 2 groups — AM and PM. In the AM group, at least 50% of treatments were given before noon. In the PM group, at least 50% of treatments were given after noon.

In this analysis, dose reductions were more common in the AM group than in the PM group in a multivariate analysis (OR, 2.29; 95% CI 1.02-5.17, P =.045).

However, there were no significant differences in early termination and recurrence rates between these 2 groups.

Based on these results, Dr Kelley and colleagues concluded that the time of day for chemotherapy administration may be “an important variable in breast cancer treatment.” Therefore, the correlation between chemotherapy timing and outcomes should be studied in a larger prospective cohort.

Read more of Cancer Therapy Advisor’s coverage of NCCN 2022 by visiting the conference page.


Kelley K, York A, Haaland B, et al. Chemotherapy timing and outcomes in early breast cancer. Presented at NCCN 2022 Annual Conference; March 31 – April 2, 2022. Abstract CLO22-059.