[The comparison of characters between invasive micropapillary carcinoma and invasive ductal carcinoma not otherwise specified of the breast].

Objective: To analyze the differences of clinicopathological characters and prognostic factors between invasive micropapillary carcinoma of the breast (IMPC) and invasive ductal carcinoma (IDC) not otherwise specified of the breast.
Methods: Patients who were treated from June 2008 to April 2016 in Breast Center of Beijing Hospital were retrospectively analyzed to evaluate the differences between IMPC (n=59) and IDC (n=1 080). Follow-up was done every 3 to 6 months postoperatively with a deadline of July 31, 2016. The curves of disease free survival (DFS) and overall survival (OS) were drawn by Kaplan-Meier method, and survival rates were compared by means of the Log-rank test. Potential prognostic variables which were identified on univariate analysis were analyzed with Cox's proportional hazards regression model for multivariate analysis.
Results: More lymph nodes were involved in IMPC group (χ(2)=12.168, P=0.007) which led to more later stage in this group (χ(2)=8.950, P=0.011). IMPC group displayed a significantly increased rate of lymphovascular invasion (LVI) compared to IDC group (χ(2)=13.511, P = 0.001). The expression rate of estrogen receptor (ER) and progesterone receptor (PR) was higher in IMPC group than that in IDC group (89.8% vs. 76.3% and 88.1% vs. 70.7%, respectively, χ(2)=5.786, 8.332, all P<0.05). In multivariate analysis performed with the variables found significant in univariate analysis, the only variable found significantly affecting DFS of IMPC group was the T stage (T1-2 and T3-4, OR=5.217, 95%CI: 1.401 to 19.430, P=0.014), while in IDC group, pathological stage (stage Ⅰ to Ⅱ and stage Ⅲ to Ⅳ, OR=1.870, 95% CI: 1.262 to 2.771, P=0.002), lymph node positive ratio (LNR) (OR=2.222, 95%CI: 1.561 to 3.162, P=0.000), PR (OR=1.856, 95%CI: 1.118 to 3.082, P=0.017), and age (<50 years old and ≥50 years old, OR=0.695, 95%CI: 0.488 to 0.989, P=0.043) were prognostic factors. There were two variables found significantly affecting OS of IMPC group, which were T stage (OR=3.713, 95%CI: 1.539 to 8.959, P=0.004) and LNR (OR=2.850, 95%CI: 1.033 to 7.862, P=0.043). While in IDC group, LNR was the only variable found significantly affecting OS (OR=2.129, 95%CI: 1.324 to 3.425, P=0.002). Compared with IDC, the patients with IMPC were more likely to have local or regional recurrence (P=0.006). Although the median DFS interval was longer in IDC group (χ(2)=9.739, P=0.002), the median OS interval was comparable between the two groups (χ(2)=0.787, P=0.375).
Conclusion: Although IMPC has lymphotropic feature, tendency of LVI and local or regional recurrence, it has an OS which is comparable with IDC.