Would you consider adjuvant capecitabine for a patient with triple-negative metaplastic carcinoma who has microinvasive residual disease (ypT1miN0) following neoadjuvant therapy?

For a patient with triple-negative metaplastic breast cancer and microinvasive residual disease (ypT1miN0)following neoadjuvant therapy, the decision to use adjuvant capecitabine is nuanced and not definitively addressed in current guidelines or trials.

1. General TNBC with Residual Disease:
   • Multiple studies, including real-world data from MD Anderson, Dana-Farber, and OSU, show that adjuvant capecitabine improves recurrence-free survival (RFS), distant RFS, and overall survival (OS) in patients with residual disease after neoadjuvant chemotherapy.
   • The CREATE-X trial (not specific to metaplastic histology) demonstrated benefit in TNBC patients with residual invasive disease, but excluded patients with ypT1mi.
2. Microinvasive Disease (ypT1mi...

Short answer: yes. Although we have data from CREATE-X, data from GEICAM were negative. Data from FinXX and SYSUCC001, however, were positive. TNBC still carries a high risk of recurrence even with small-volume residual disease. Retrospective and prospective data suggest that chemotherapy is particularly important in the metaplastic subtype, and as it prognosticates poor outcome, it likely means higher absolute benefit.