Impact of diabetes and glycemic control on pathologic complete response after neoadjuvant chemotherapy in breast cancer in an Afro-Caribbean population: A retrospective cohort study.

e12625 Background: Diabetes mellitus and hyperglycemia may adversely affect cancer outcomes and response to systemic therapy in breast cancer (Peairs et al., 2010; Srokowski et al., 2009). Pathologic complete response (pCR) after neoadjuvant chemotherapy (NACT) is a validated surrogate marker of improved long-term outcomes (Spring et al., 2020; van Mackelenbergh et al., 2023). This study evaluated whether diabetes and baseline HbA1c are associated with pCR in breast cancer patients receiving NACT. Methods: We conducted a retrospective cohort study of breast cancer patients treated with NACT at a single institution. Included patients had a documented neoadjuvant chemotherapy regimen, known pCR status, and known diabetes status, defined as HbA1c ≥ 6.5. The primary outcome was pCR (yes/no). The main exposures were diabetes (yes/no) and HbA1c at diagnosis. Categorical variables were compared using Fisher’s exact test, and continuous variables using Welch’s t-test; multivariable logistic regression was used to estimate adjusted odds ratios (ORs) for pCR, including diabetes, age, BMI, and HbA1c. Results: Of 153 patients who received NACT, 52 had complete data for diabetes and pCR and were included in the primary analysis. Among these, 40 (76.9%) had diabetes and 12 (23.1%) did not have diabetes; 30 (57.7%) achieved pCR. pCR occurred in 75.0% of patients without diabetes versus 52.5% of patients with diabetes (Fisher’s exact OR = 0.37; p = .20). Baseline HbA1c was higher in patients without pCR than in those with pCR (mean 8.05% vs. 7.19%; p = .22). In multivariable logistic regression, diabetes was not an independent predictor of pCR (adjusted OR = 0.33; 95% CI [0.03, 4.31]). Age, BMI, and HbA1c were also not significantly associated with pCR. Conclusions: In this cohort, diabetes status and baseline HbA1c were not significantly associated with pCR after NACT, although both diabetes and higher HbA1c showed non-significant trends toward lower pCR rates. Larger, adequately powered studies are needed to clarify the impact of diabetes and glycemic control on neoadjuvant treatment response in breast cancer.