Differences in severity of chemotherapy-induced nausea and vomiting between neoadjuvant and adjuvant chemotherapy in patients with breast cancer: analysis of data from two prospective observational studies

Purpose: We assessed the differences in chemotherapy-induced nausea and vomiting (CINV) severity in patients with breast cancer, receiving neoadjuvant chemotherapy (NAC) and adjuvant chemotherapy (AC). Methods: CINV severity in patients on anthracycline-based NAC (n = 203) and AC (n = 79) was assessed at baseline (C0) and after the first and fourth chemotherapy using a 10-point Likert scale. Group-by-time interaction term was used to evaluate the effect of the group on changes in CIN (cCIN) and CIV (cCIV) from C0 to the follow-up periods (C1, C4). If insignificant, group effects were analyzed without the interaction term. Subgroup analysis was performed based on age 50. In statistical analyses, sociodemographic and clinical variables that differed between groups were adjusted for. Results: The effect of group by follow-up period was not significant in cCIN and cCIV. The AC group showed a significantly higher change in the severity of cCIN compared to the NAC group (estimated mean = 1.133, 95% CI = 0.104–2.161, p = 0.031), but there was no difference in cCIV. In those ≤ 50 years, significant differences in cCIN severity (estimated mean = 1.294, 95% CI = 0.103–2.484, p = 0.033) were observed, but not in cCIV. In those > 50 years, neither cCIN nor cCIV differed significantly between groups. Conclusions: NAC in breast cancer patients showed less severe CIN than adjuvant chemotherapy AC, but not in those over 50. Clinicians should recognize that the severity of CIN may vary across different chemotherapy settings and adjust their management accordingly. Trial registration: The clinical trial registration (www.ClinicalTrials.gov) numbers were NCT 01887925 (the registration date is from June 20, 2013, to November 27, 2015) and NCT02011815 (the registration date is from December 10, 2013, to September 22, 2019).