Distinguishing hemoglobin nadir from clinically significant anemia events during curative treatment for early breast cancer: Mapping hemoglobin trajectories.

Abstract

e23389 Background: Anemia is a frequent complication during treatment for early breast cancer (EBC), yet the temporal relationship between hemoglobin (Hb) decline, Hb nadir & clinically significant anemia events (CSAE) remain poorly defined. Characterization of anemia trajectories & event timing may inform risk stratification & supportive care planning. Methods: We conducted a retrospective cohort study of consecutive patients with EBC undergoing curative surgery between Jan'24 to Aug'25 at a tertiary cancer center. Hb values were captured at baseline, at surgery & at nadir. The primary endpoint was time to CSAE, defined as any of the following: Hb < 8.5 g/dL, ≥2 g/dL decline from baseline, or red blood cell transfusion. Time to CSAE was analyzed independently of time to Hb nadir & both were calculated for those receiving neoadjuvant (NACT) or adjuvant (ACT) chemotherapy. Those without CSAE were censored at the end of predefined risk period. Prespecified covariates evaluated for time-to-event associations included age, menopausal status, baseline anemia status, tumor grade, nodal status, tumor-subtype, therapy setting (NACT or ACT) & chemotherapy intensity (dose-dense and/or platinum-based). Results: Among 1,228 patients (median age 53 yrs; SD 11.2), 71.1% were postmenopausal. Baseline anemia was present in 45.8% (mild 23.5%, moderate 20.0%, severe 2.3%). Mean baseline Hb was 11.91 g/dL (SD 1.62), declining to 10.75 g/dL (SD 1.32) at surgery among NACT recipients, with a nadir of 9.73 g/dL (SD 1.49) during perioperative therapy. CSAE occurred in 67.4%, with a median time to event of 21 wks (95% CI 19.5–22.4), occurring independently of Hb nadir timing (median 17 wks). On univariate analysis, absence of baseline anemia, age > 50 yrs, postmenopausal status, & receipt of NACT were each associated with earlier CSAE. On multivariable cox analysis, receipt of NACT (HR 1.93, 95% CI 1.31–2.83; p = 0.001), absence of baseline anemia (HR 1.52, 95% CI 1.23–1.85; p < 0.001), & postmenopausal status (HR 1.41, 95% CI 1.06–1.87; p = 0.018) remained independently associated with higher CSAE risk. Conclusions: In this real-world EBC cohort, CSAE were common & independent of Hb nadir timing. Notably, patients without baseline anemia experienced earlier CSAE. Postmenopausal status & receiving NACT further increased CSAE risk. These findings support proactive anemia risk assessment across all patients, including those with normal baseline Hb, to inform anticipatory supportive care strategies. Univariate estimates and multivariable predictors of clinically significant anemia events. Variable Category Time to CSAE (wk) 95% CI Multivariable HR (95% CI) NACT Yes 20.0 18.6–21.3 1.93 (1.31–2.83) No 26.0 21.6–30.3 Baseline anemia Absent 19.0 17.3–20.6 1.52 (1.23–1.85) Present 26.0 20.7–31.2 Menopause Post 20.0 18.4–21.5 1.41 (1.06–1.87) Pre 30.0 18.4–41.6