265P - Association of clinical benefit of adjuvant capecitabine and RCB class in triple negative breast cancer (TNBC) patients with residual disease following neoadjuvant chemotherapy

Background

In early stage triple negative breast cancer (TNBC), surgery following neoadjuvant chemotherapy is standard of treatment. Adjuvant capecitabine showed improved survival in patients with residual disease. However, the data on clinical benefits of adjuvant capecitabine according to residual cancer burden (RCB) are insufficient.

Methods

Among patients with early TNBC who received neoadjuvant chemotherapy followed by surgery at Asan Medical Center in Seoul, Republic of Korea, between February 2008 and December 2021, those with residual tumors were included. Recurrence-free survival (RFS) as per STEEP version 2.0 was compared according to adjuvant capecitabine and RCB class.

Results

The study included 922 patients, with a median age of 47 years (range: 24–78). Of these, 230 (24.9%) received adjuvant capecitabine (capecitabine group) while 692 (75.0%) did not receive any adjuvant chemotherapy (observation group). Most patients (87.8%) received anthracycline and cyclophosphamide, with or without taxane, as part of their neoadjuvant chemotherapy regimen. RCB class well discriminated patients into prognostic groups with 2-year RFS of 69%, 58%, and 31% for patients with RCB class 1 (n=126), 2 (n=577), and 3 (n=219), respectively. No significant differences in clinical characteristics, including RCB class, were observed between the two groups (p=0.23). RFS analysis showed a trend toward improved outcomes in the capecitabine group (log-rank p=0.06). Specifically, no significant differences were found in RFS between the groups for RCB class 1 (p > 0.99) and 2 (p=0.43). However, in RCB class 3 patients, capecitabine group showed significantly better RFS compared to the observation group (log-rank p=0.02) and this was consistent in the multivariable analysis, showing a hazard ratio of 0.45 (95% CI: 0.25–0.81, p=0.007), indicating a statistically significant benefit of adjuvant capecitabine in this subgroup.

Conclusions

Adjuvant capecitabine showed clinical benefit in patients with TNBC who had residual tumor after neoadjuvant chemotherapy, and the benefit was more significant in patients with higher tumor burden with RCB class 3.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.