Adjuvant chemotherapy for small, lymph node-negative, triple-negative breast cancer: A single-center study and a meta-analysis of the published literature.

Background Current guidelines recommend adjuvant chemotherapy for patients with small, lymph node-negative, triple-negative breast cancer (TNBC) measuring >5 mm (T1b disease), but clinical evidence to support this recommendation is lacking. Thus, the current study aimed to evaluate the survival benefit of adjuvant chemotherapy in patients with T1N0M0 (measuring <= 2 cm) TNBC with different tumor sizes. Methods The authors retrospectively evaluated consecutive patients with pT1N0M0 TNBC who were diagnosed between 2000 and 2016 at Sun Yat-Sen University Cancer Center. For the meta-analysis, electronic medical databases were searched for all relevant studies regarding the effect of adjuvant chemotherapy on the target population. Results Of the 351 enrolled patients, 309 (88%) received adjuvant chemotherapy and 42 patients (12%) did not. The distribution by T classification was T1a in 19 patients (5.4%), T1b in 67 patients (19.1%), and T1c in 265 patients (75.5%). Adjuvant chemotherapy significantly improved recurrence-free survival (RFS) in the patients with T1c disease, but not those with T1b and T1a disease. Meanwhile, there was no difference in RFS noted according to the chemotherapy regimen among patients with T1c disease. Seven eligible studies comprising 1525 patients with T1N0M0 (941 with T1a/bN0M0) were included in the meta-analysis. The meta-analysis demonstrated that adjuvant chemotherapy significantly reduced the rate of disease recurrence for patients with T1a/b disease as a group, but the population driving that was only patients with T1b disease, not those with T1a disease. Conclusions Although the retrospective analysis demonstrated a survival benefit of adjuvant chemotherapy only for patients with T1cN0 TNBC, the meta-analysis showed it also is beneficial for individuals with T1bN0 TNBC. For patients with T1cN0M0 TNBC, less intensive chemotherapy regimens achieve an excellent survival outcome similar to that of intensive anthracycline and taxane combination chemotherapy.