Racial differences in acute toxicities of neoadjuvant or adjuvant chemotherapy in patients with early-stage breast cancer

Abstract 

Background

Racial disparities in breast cancer outcomes are attributed to differences in baseline tumour characteristics and biology, stage, age, ethnic background and socioeconomic factors. However, little is known about racial differences in treatment-related toxicities. We hypothesised that racial/ethnic differences result in differential tolerance to chemotherapy potentially, leading to compromised dose intensity/density of chemotherapy in patients with early-stage breast cancer.

Methods

Data were collected from patients treated at five international centers for early breast cancer with the same adjuvant/neoadjuvant chemotherapy (FEC 100: fluorouracil 500mg/m², epirubicin 100mg/m², and cyclophosphamide 500mg/m²,every 21d for 3–6 cycles). Toxicities were assessed by first episode of ⩾grade 2 toxicity.

Results

Toxicities were compared according to four race/ethnicity groups (103 Caucasian, 30 African American, 164 Asian, and 34 Hispanic patients). Tumour characteristics across four race/ethnicity groups were similar. Asians had a significantly higher rate of grade 3 haematologic toxicity than Caucasians, African Americans or Hispanic women (32%, 16%, 10%, and 15%, respectively; p<0.05). In multivariate analysis, only lower BMI was associated with a higher incidence of ⩾grade 3 toxicities. However, no significant differences in chemotherapy dose intensity/density were shown across the four race/ethnicity groups.

Conclusion

Racial differences in acute toxicity were noted in women with breast cancer who were treated with FEC 100 chemotherapy, suggesting that extrapolating toxicities from chemotherapy across ethnicities is not possible and emphasising the need to validate safety of chemotherapeutic regimens in patients of different ethnicities by enhancing the participation of minorities in clinical trials.

Keywords: Breast cancer, Racial/ethnic difference, Toxicity, Chemotherapy