title: Is adjuvant chemotherapy necessary for patients with microinvasive breast cancer after surgery?
abstract: OBJECTIVE
  Survival and treatment of patients with microinvasive breast cancer (MIBC) remain controversial. In this paper, we evaluated whether adjuvant chemotherapy is necessary for patients with MIBC to identify risk factors influencing its prognosis and decide the indication for adjuvant chemotherapy.
  
  
  METHODS
  In this retrospective study, 108 patients with MIBC were recruited according to seventh edition of the staging manual of the American Joint Committee on Cancer (AJCC). The subjects were divided into chemotherapy and non-chemotherapy groups. We compared the 5-year disease-free survival (DFS) and overall survival (OS) rates between groups. Furthermore, we analyzed the factors related to prognosis for patients with MIBC using univariate and multivariate analyses. We also evaluated the impact of adjuvant chemotherapy on the prognostic factors by subgroup analysis after median follow-up time of 33 months (13-104 months).
  
  
  RESULTS
  The 5-year DFS and OS rates for the chemotherapy group were 93.7% and 97.5%, whereas those for the non-chemotherapy group were 89.7% and 100%. RESULTS indicate that 5-year DFS was superior, but OS was inferior, in the former group compared with the latter group. However, no statistical significance was observed in the 5-year DFS (P=0.223) or OS (P=0.530) rate of the two groups. Most relevant poor-prognostic factors were Ki-67 overexpression and negative hormonal receptors. Cumulative survival was 98.2% vs. 86.5% between low Ki-67 (≤20%) and high Ki-67 (>20%). The hazard ratio of patients with high Ki-67 was 16.585 [95% confidence interval (CI), 1.969-139.724; P=0.010]. Meanwhile, ER(-)/PR(-) patients with MIBC had cumulative survival of 79.3% compared with 97.5% for ER(+) or PR(+) patients with MIBC. The hazard ratio for ER(-)/PR(-) patients with MIBC was 19.149 (95% CI, 3.702-99.057; P<0.001). Subgroup analysis showed that chemotherapy could improve the outcomes of ER(-)/PR(-) patients (P=0.014), but not those who overexpress Ki-67 (P=0.105).
  
  
  CONCLUSIONS
  Patients with MIBC who overexpress Ki-67 and with negative hormonal receptors have relatively substantial risk of relapse within the first five years after surgery. However, adjuvant chemotherapy can only improve the outcomes of ER(-)/PR(-) patients, but not those who overexpress Ki-67. Further studies with prolonged follow-up of large cohorts are recommended to assess the prognostic significance and treatment of this lesion.
authors.affiliation: The Second of Department of Breast Oncology.
authors.forename: Hai-Fei
authors.initials: HF
authors.lastname: Niu
authors.affiliation: The Second of Department of Breast Oncology.
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Wei
authors.affiliation: Department of Immunology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer.
authors.forename: Jin-Pu
authors.initials: JP
authors.lastname: Yu
authors.affiliation: The Second of Department of Breast Oncology.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Lian
authors.affiliation: The Second of Department of Breast Oncology.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhao
authors.affiliation: The Second of Department of Breast Oncology.
authors.forename: Zi-Zheng
authors.initials: ZZ
authors.lastname: Wu
authors.affiliation: The Second of Department of Breast Oncology.
authors.forename: Jun-Tian
authors.initials: JT
authors.lastname: Liu
keywords: Microinvasive breast cancer; adjuvant chemotherapy; survival