Is adjuvant chemotherapy necessary for patients with microinvasive breast cancer after surgery?

Hai-Fei Niu, Li-Juan Wei, Jin-Pu Yu, Zhen Lian, Jing Zhao, Zi-Zheng Wu, Jun-Tian Liu


Objective: Survival and treatment of patients with microinvasive breast cancer (MIBC) remain controversial. In this paper, weevaluated whether adjuvant chemotherapy is necessary for patients with MIBC to identify risk factors influencing its prognosis anddecide the indication for adjuvant chemotherapy.

Methods: In this retrospective study, 108 patients with MIBC were recruited according to seventh edition of the staging manual ofthe 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 thefactors related to prognosis for patients with MIBC using univariate and multivariate analyses. We also evaluated the impact ofadjuvant chemotherapy on the prognostic factors by subgroup analysis after median follow-up time of 33 months (13-104months).

Results: The 5-year DFS and OS rates for the chemotherapy group were 93.7% and 97.5%, whereas those for the nonchemotherapygroup were 89.7% and 100%. Results indicate that 5-year DFS was superior, but OS was inferior, in the formergroup 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 hormonalreceptors. Cumulative survival was 98.2% vs. 86.5% between low Ki-67 (≤20%) and high Ki-67 (>20%). The hazard ratio ofpatients with high Ki-67 was 16.585 [95% confidence interval (CI), 1.969-139.724; P=0.010]. Meanwhile, ER(-)/PR(-) patientswith MIBC had cumulative survival of 79.3% compared with 97.5% for ER(+) or PR(+) patients with MIBC. The hazard ratio forER(-)/PR(-) patients with MIBC was 19.149 (95% CI, 3.702-99.057; P<0.001). Subgroup analysis showed that chemotherapy couldimprove 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 ofrelapse 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 toassess the prognostic significance and treatment of this lesion.


Microinvasive breast cancer; adjuvant chemotherapy; survival

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