The impact of molecular status on survival outcomes for invasive micropapillary carcinoma of the breast

Abstract

Invasive micropapillary carcinoma (IMPC) is an uncommon variant of breast cancer. Previous studies demonstrated this subtype is often hormone receptor (HR)‐positive, resulting in survival outcomes similar to invasive ductal carcinoma. However, many of these studies were conducted prior to HER2 testing availability. We aim to determine the impact of molecular marker status (including HER2 status) on IMPC survival outcomes. The National Cancer Data Base (NCDB) was used to retrieve patients with biopsy‐proven IMPC from 2007 to 2012. Only patients with known HR and HER2 status were included. Cox multivariate regression was used to determine prognostic factors. In total, 865 patients were included; median follow‐up was 2.5 years. Overall, 651 patients (75.3%) had HR + HER2− disease, 128 (14.8%) had HR + HER2+ disease, 41 (4.7%) had HR‐HER2 + disease, and 45 (5.2%) had triple negative disease. Patients with triple negative disease were more likely to have poorly differentiated histology (66.7%), lymphovascular invasion (73.3%), stage 3 disease (37.8%), undergone mastectomy (68.9%), and positive surgical margins (15.6%). On Cox multivariate regression, those with triple negative disease had worse overall survival (hazard ratio [HR] 7.28, P < 0.001). Other adverse prognostic factors included African‐American descent (HR 2.24, P = 0.018), comorbidity score of 1 (HR 2.50, P = 0.011), comorbidity score ≥2 (HR 3.27, P = 0.06), and ≥3 positive lymph nodes (HR 3.23, P = 0.007). Similar to invasive ductal carcinoma, triple negative disease in IMPC results in worse survival outcomes. This is the largest and first study to characterize molecular status (including HER2 status) in patients with IMPC and its impact on survival outcomes.

Invasive Micropapillary Carcinoma: A Rare Case of Male Breast Cancer

“…The patient's immunohistochemical studies showed hormone positive and HER2/Neu negative cancer, indicating that it is a well differentiated cancer with good prognostic values. Like other types of breast cancer, triple negative (ER-, PR-, HER2/Neu-) disease is associated with higher grade, further advanced stage, and an increased propensity for lymphovascular invasion [9]. According to Gokce et al, hormone receptor negativity is hypothesized to exhibit more aggressive behavior in pure IMPC versus mixed cases, potentially accounting for our patient's lack of significant metastasis compared to that expected from the literature [10].…”

Prognosis of invasive micropapillary carcinoma compared with invasive ductal carcinoma in breast: A meta-analysis of PSM studies

“…(3A) summarized RFS using a fixed-effect model, (3B) summarized RFS using a random-effect model. as matching variables, since it has been reported that IMPC had a higher HR positive rate [31]. Therefore, in the present metaanalysis, the two groups (IMPC and IDC) are well balanced and comparable in node status and molecular subtypes, thus decreasing the selection bias to a minimum.…”

“…Therefore, it is reasonable that all the PSM studies employed node status as a matching variable to balance the two groups. Besides age and node status, half of eligible studies (4/8) including 79.2% IMPC patients (1665 of the total 2102) also employed HR status and HER-2 status as matching variables, since it has been reported that IMPC had a higher HR positive rate [ 31 ]. Therefore, in the present meta-analysis, the two groups (IMPC and IDC) are well balanced and comparable in node status and molecular subtypes, thus decreasing the selection bias to a minimum.…”

Long-term Survival Outcomes of Invasive Micropapillary Carcinoma of the Breast: A Population-based Study

“…We found that BCSS and OS were different between the IMPC and IDC group only in Luminal A subgroup, but not in Luminal B, triplenegative, and HER2-enriched subgroups. Lewis et al also concluded that the prognosis of Triple-negative IMPC is as poor as that of IDC [22] .…”