Similar prognoses for invasive micropapillary breast carcinoma and pure invasive ductal carcinoma: a retrospectively matched cohort study in China

An overview of invasive micropapillary carcinoma of the breast: past, present, and future

Invasive micropapillary carcinoma of the breast (IMPC) exhibits a unique micropapillary structure and "inside-out" growth pattern. Despite its extremely low incidence, IMPC has attracted considerable attention owing to its poor prognosis. Since Siriaunkgul and Tavassoli first proposed the term IMPC in 1993 to describe its morphological characteristics, with tumor cell clusters arranged in a pseudopapillary structure within the glandular cavity, its diagnostic rate has substantially increased. Based on the in-depth study of IMPC, a more comprehensive understanding of its epidemiology, clinicopathological features, and diagnostic criteria has been achieved in recent years. The pathogenesis and specific therapeutic targets of IMPC remain unclear. However, numerous studies have delved into its high-risk biological behavior. This review discusses the opportunities and challenges associated with IMPC.

Long-term outcome of invasive pure micropapillary breast cancer compared with invasive mixed micropapillary and invasive ductal breast cancer: a matched retrospective study

PURPOSE

Data on the prognostic impact of the micropapillary component in breast cancer are limited. The purpose of this study was to investigate the clinicopathological characteristics and long-term outcomes of pure and mixed invasive micropapillary breast cancer (IMPC) patients compared to invasive ductal cancer (IDC) patients.

METHODS

This retrospective study analysed all IMPC and IDC patients treated at the European Institute of Oncology (IEO) between 1997 and 2019. The overall cohort of IMPC patients was divided in two groups, pure and mixed IMPC. Each patient with mixed or pure IMPC was matched with one patient with IDC, based on year of surgery, age, pT, pN, and molecular subtype.

RESULTS

A total of 30,115 IDC, 120 pure IMPC and 150 mixed IMPC patients were considered eligible. Compared to IDC, pure and mixed IMPC patients presented a higher rate of locally advanced disease (pT2-T3, pN2-N3), vascular invasion, and Luminal B subtype. After matching, pure and mixed IMPC showed a significant higher rate of vascular invasion compared to IDC patients (p < 0.001). Invasive disease-free survival was better in IDC compared to pure IMPC patients (p = 0.11). Long-term overall survival was significantly worse in pure IMPC group compared to IDC group (p = 0.004), being instead similar between mixed IMPC vs matched IDC (p = 0.07).

CONCLUSION

These real-world data reported the worse prognosis of pure IMPC compared to IDC, highlighting the peculiar prognostic value of the micropapillary subtype itself in the decision-making process of IMPC management. An accurate pre-surgical diagnostic evaluation and a multidisciplinary approach are pivotal to best personalize its treatment.

Correlation Analysis of Digital Mammography, Ultrasonography, and Pathologic Features in Pure Invasive Micropapillary Carcinoma of the Breast (PIMPC)

Purpose

This study determined the digital mammography and ultrasonography imaging features of pure invasive micropapillary carcinoma of the breast (PIMPC) and the correlation with pathologic features.

Patients Methods

Nineteen patients diagnosed with PIMPC at Yantaishan Hospital from October 2015 to February 2022 were included in the study group. Forty patients with breast masses diagnosed as nonspecific invasive ductal carcinoma of the breast (NIDC) from July to December 2021 were included in the control group. Digital mammography and ultrasonography features were compared between the two groups.

Results

Patients with PIMPC had a younger age profile compared to patients with NIDC (P=0.017). Moreover, PIMPC masses were smaller than NIDC masses (P=0.040). Imaging features analysis revealed significant differences in age groups (<45 years: χ²=5.971, P=0.044) and the presence of spiculations or the crab claw sign (χ²=8.583, P=0.004) between patients with PIMPC and NIDC. However, there were no statistically significant differences in the presence of calcifications, blood flow grading, pathologic molecular subtypes between the study and control groups. The Ki-67 proliferative index (χ²=1.052, P=0.389), vascular invasion (χ²=2.263, P=0.197), and lymph node metastasis (χ²=1.968, P=0.386) showed no significant differences between PIMPC and NIDC patients.

Conclusion

PIMPC imaging features show specificity, such as tiny breast masses, spiculated edges, or crab claw-like patterns, and malignant signs appeared when the lesion was <2 cm in diameter. PIMPC mainly occurs in middle-aged women 45-59 y of age. Patients with PIMPC and NIDC of the breast are frequently associated with lymph node metastases and greater than one-half of the cases (74%) were shown to have a Ki-67 index >30%, suggesting a significant risk of recurrence and metastasis. Early therapeutic care for these patients is crucial. These results warrant further validation with additional samples from several centers due to the limited single-center sample size in the current study.

Increased Expression of LEF1 and β-Catenin in Invasive Micropapillary Carcinoma of the Breast is Associated With Lymphovascular Invasion and Lymph Node Metastasis

Invasive micropapillary breast carcinoma (IMPC) is a rare breast cancer subtype characterized by small tumor cell clusters with loss of stromal attachment, an inside-out growth appearance, and lymphotropism. IMPC is associated with high incidence of lymphovascular invasion (LVI) and lymph node metastasis. Activated Wnt signaling has been implicated in the metastasis of other aggressive breast tumors, including triple-negative and basal-like carcinomas. In this study, we tested whether activated Wnt signaling could be detected in IMPC. Upon ligand binding, the central mediator of the Wnt pathway, β-catenin, accumulates in the cytosol and translocates to the nucleus where it forms a complex with lymphoid enhancer-binding factor 1 (LEF1) to regulate transcription. We performed immunostaining for β-catenin and LEF1 on a well-annotated cohort of 40 breast tumors and nodal metastases displaying micropapillary histopathology. Strong nuclear accumulation of β-catenin was not observed, however a dim cytosolic and/or nuclear accumulation of β-catenin was sometimes seen in IMPC and this expression pattern was significantly associated with nodal metastasis. β-catenin expression correlated with the upregulation of LEF1 in IMPC. LEF1 expression was detected in 26 of 40 (65%) cases and was specifically enriched at the invasive front of the tumor and in tumor clusters undergoing LVI. Detection of LEF1 expression in the primary tumor was associated with an increased rate of LVI, lymph node metastasis, and disease relapse. LEF1 and β-catenin expression levels were significantly higher in metastases compared with primary tumors. In summary, this study demonstrates an association between the upregulation of β-catenin/LEF1 and the metastasis of IMPC.

Micropapillary Breast Carcinoma: From Molecular Pathogenesis to Prognosis

Invasive micropapillary carcinoma (IMPC) of the breast is an infrequent type of breast cancer often discussed for its potency for lymphovascular invasion and difficulty in accurate imaging estimation. Micropapillary carcinomas are noted to be present as larger tumors, of higher histological grade and a notably higher percentage of disease-positive lymph nodes. Hormonal and HER-2 positivity in IMPC is also commoner when compared to other NST carcinomas. IMPC occurs either as a pure form or more often as a component of mixed Non-Specific Type (NST) carcinoma. The latest data suggest that despite having comparable survival rates to other histological subtypes of breast carcinoma, effective surgical treatment often requires extended surgical margins and vigilant preoperative axillary staging due to an increased incidence of lymph node invasion, and locoregional recurrence. Moreover, the presence of micropapillary in situ components within tumors also seems to alter tumor aggression and influence the nodal disease stage. In this review, we present an overview of the current literature of micropapillary carcinoma of the breast from biology to prognosis, focusing on biological differences and treatment.

Rare Breast Cancer Subtypes

PURPOSE OF REVIEW

Breast cancer is a collection of diseases including the more common invasive ductal and lobular carcinomas and rarer subtypes of breast cancer. This review summarizes the features of rare breast cancers.

RECENT FINDINGS

Each of the rare tumors has defined pathological and clinical features that impact treatment recommendations. In this review, we summarize these for each rare type of breast cancer and where available we include molecular features of each tumor. Rare subtypes of breast cancer each have unique features. In many cases, data is limited for the optimal treatment approaches.

Comparison of clinicopathological characteristics and prognosis among patients with pure invasive ductal carcinoma, invasive ductal carcinoma coexisted with invasive micropapillary carcinoma, and invasive ductal carcinoma coexisted with ductal carcinoma in situ: A retrospective cohort study

This paper aimed to analyze the clinicopathological characteristics of invasive ductal carcinoma with an invasive micropapillary carcinoma component (IDC + IMPC), invasive ductal carcinoma with a ductal carcinoma in situ component (IDC + DCIS), and compare the clinicopathological characteristics and prognosis to those of IDC.A total of 1713 patients (130 IDC + IMPC cases, 352 IDC + DCIS cases, and 1231 pure IDC cases) who underwent appropriate surgery from June 2011 to September 2017 were retrospectively selected.Compared to the pure IDC and IDC + DCIS patients, the IDC + IMPC patients presented with more aggressive characteristics, such as a higher proportion of vascular invasion (P < .001), fewer progesterone receptor (PR)-positive patients (P < .001), a lower proportion of cases in American Joint Committee on Cancer stage I (P < .001), a higher recurrence risk (P < .001), more deaths (P < .001), and more metastatic cases (P < .001). Compared to the pure IDC and IDC + IMPC patients, the IDC+DCIS patients presented with less aggressive characteristics, such as a higher proportion of estrogen receptor-positive patients (P < .001) and PR-positive patients (P < .001), a lower proportion of cases with nerve invasion (P < .001) and vascular invasion (P < .001), a higher proportion of cases in American Joint Committee on Cancer stage I (P < .001), fewer deaths (P < .001), and fewer metastatic cases (P < .001). The patients with IDC + DCIS had significantly better disease-free survival (DFS) and overall survival (OS) compared to those with pure IDC and IDC + IMPC (P < .001). The patients with IDC + IMPC had significantly worse DFS and OS compared to those with pure IDC and IDC + DCIS (P < .001). In univariate analysis, the presence of an IMPC component in IDC (P = .007), estrogen receptor status (P = .05), and PR status (P = .003) were factors associated with OS. In multivariate analysis, coexisting IMPC (P = .04) was the only independent prognostic factor associated with OS.Compared to IDC and IDC + DCIS, IDC + IMPC had more aggressive characteristics and significantly worse DFS and OS. Compared to IDC and IDC + IMPC, IDC + DCIS had less aggressive characteristics and significantly better DFS and OS.

Assessment of stromal tumor infiltrating lymphocytes and immunohistochemical features in invasive micropapillary breast carcinoma with long-term outcomes

PURPOSE

We studied the long-term outcomes of invasive micropapillary carcinoma (IMPCs) of the breast in relation to stromal tumor infiltrating lymphocytes (sTILs), prognostic biomarkers and clinicopathological features.

METHODS

Stage I-III IMPCs treated with upfront surgery at our institution (January 2000 and December 2016) were included. Central pathology review was performed and sTILs (including zonal distribution and hot spot analysis) and tumor-associated plasma cells (TAPC) were evaluated. Expression of P53, BCL2, FOXP3, and WT1, which are variably linked to breast cancer prognosis, was measured by immunohistochemistry using tissue microarrays. Time-to-event endpoints were distant recurrence free interval (DRFI) and breast cancer-specific survival (BCSS).

RESULTS

We included 111 patients of whom 59% were pure IMPCs. Standard clinicopathological features were comparable between pure and non-pure IMPCs. Overall, the mean sTILs level was 20% with higher proportion of sTILs present at the invasive front. There were no significant differences between pure- and non-pure IMPCs in sTILs levels, nor in the spatial distribution of the hot spot regions or in the distribution of TAPC. Higher sTILs correlated with worse DRFI (HR = 1.55; p = 0.0172) and BCSS (HR = 2.10; p < 0.001).

CONCLUSIONS

Clinicopathological features, geographical distribution of sTILs and TAPC are similar between pure and non-pure IMPCs. Despite a high proportion of grade 3 tumors and lymph node involvement, we observed a low rate of distant recurrences and breast cancer-related death in this cohort of stage I-III IMPCs treated with primary surgery. Caution in interpretation of the observed prognostic correlations is required given the very low number of events, warranting validation in other cohorts.

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

BACKGROUND

Invasive micropapillary carcinoma (IMPC) is a rare histological subtype of breast cancer. The outcome of IMPC remains controversial; we conducted a meta-analysis of propensity score matching (PSM) studies to evaluate the prognostic difference between IMPC and invasive ductal carcinoma (IDC).

METHODS

We searched PubMed, EMBASE and the Cochrane library for PSM studies comparing survival data between IMPC and IDC. The summarized odds ratios (ORs) and 95% confidence interval (95% CI) are calculated by STATA software utilizing fixed-effect or random-effect models, depending on the heterogeneity of the eligible studies.

RESULTS

Eight PSM studies including 2102 IMPC patients are included in the meta-analysis. Compared with IDC, IMPC has a similar overall survival (OS) (estimated OR = 0.87, 95% CI: 0.61-1.25), but a shorter relapse free survival (RFS) (estimated OR = 1.31, 95% CI: 1.06-1.61); the shorter RFS might owe to the significantly higher loco-regional recurrence rate of IMPC (estimated OR = 3.60, 95% CI: 1.99-6.52). Funnel plots and Egger's tests are used to evaluate publication bias and the p value for OS and RFS are 0.036 and 0.564 respectively.

CONCLUSIONS

Our results demonstrate that compared with IDC, IMPC exhibits a similar, even favorite OS, but a shorter RFS; and the shorter RFS might owe to the significantly higher loco-regional recurrence rate of IMPC. These results could contribute to the individualized therapy and follow-up strategies for IMPC patients.

A Competing Nomogram to Predict Survival Outcomes in Invasive Micropapillary Breast Cancer

Background: Although it is widely accepted that invasive micropapillary carcinoma (IMPC) presents more aggressive behavior and has a higher aggressive behavior, the prognosis of IMPC compared with invasive ductal carcinoma (IDC) remains controversial. We conducted this study to explore gene expression profiles of IMPC and establish a competing nomogram that predicts the survival outcomes across these two groups of patients. Methods: Data from the Surveillance, Epidemiology, and End Results (SEER) database were reviewed. Propensity score matching (PSM) was used to adjust for potential baseline confounding between IMPC and IDC group. The Kaplan-Meier method was used to calculate the occurrence of overall mortality. The Gray method was used to estimate the rate of breast cancer specific death (BCSD). A competing regression model was used to evaluate factors associated with BCSD. A nomogram based on the competing risk regression model was established to predict individual outcomes. IMPC-specific gene expression profiles were explored using microarrays data from the Gene Expression Omnibus (GEO) database. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) enrichment analyses were performed. Results: In this study, 330786 (99.62%) patients with IDC 1247 (0.38%) patients with IMPC were included. Patients with IMPC had more lymph node involvement and a larger tumor size compared with those with IDC. After PSM, many distributional differences were eliminated, showing that the IMPC and IDC group were more similar. Patients with IMPC had a favorable prognosis with statistical significance compared with patients with IDC (overall mortality HR = 0.68; 95%CI, 0.53-0.86; P = 0.002). Based on Gray method, patients with IMPC had a favorable prognosis with significant statistical significance compared with patients with IDC (BCSD SHR = 0.64; 95%CI, 0.47-0.88; P = 0.006). Multivariate analysis based on competing risk model demonstrated that IMPC was a favorable independent factor for BCSD. The nomogram could accurately predict BCSD with a high internal and external validated C-index (0.835, 0.818 respectively). A total of 53 upregulated differentially expressed genes (DEGs) and 40 downregulated DEGs of IMPC was identified. The GO analysis results showed that downregulated DEGs were significantly enriched in extracellular structure organization, extracellular matrix, cell-substrate adhesion junction. KEGG analysis of selective gene sets shows that downregulated DEGs significantly enriched for processes related to carbon metabolism, Rap1 signaling pathway. Conclusion: In the current study, IMPC accounted for 0.38% of the entire cohort. IMPC was found to be a favorable independent prognostic factor. The present study identified gene expression profiles and signal pathways of IMPC. The developed nomogram can help the oncologists to predict individual outcomes more accurately.

High Expression of Plakoglobin Promotes Metastasis in Invasive Micropapillary Carcinoma of the Breast via Tumor Cluster Formation

Invasive micropapillary carcinoma of the breast (IMPC) is a rare subtype of breast cancer that has a high frequency of lymph node (LN) involvement and metastasis to distant organs. IMPC is characterized by distinct histomorphology and unfavorable prognosis when compared with invasive ductal carcinoma no special type (IDC-NST). However, the underlying molecular mechanisms remain unclear. We reported here that plakoglobin, as a key component in cell adhesion, can promote collective metastasis through facilitating IMPC clusters formation. In comparing the clinicopathological features of 451 IMPC patients and 282 IDC-NST patients, our results showed that tumor emboli were significantly higher in IMPC patients and were associated with a high frequency of metastasis. Both in vitro and in vivo data showed overexpression of plakoglobin in both the cell membrane and the cytoplasm of IMPC clusters. When plakoglobin was knocked down in IMPC cell models, the tumor cell clusters were depolymerized. Using mouse models, we validated the metastatic potential of tumor clusters was higher than single cells in vivo. Further analysis showed that higher expression of plakoglobin was able to promote activation of the PI3K/Akt/Bcl-2 pathway, which might protect the clusters from anoikis. Our data indicate that plakoglobin promotes tumor cluster formation in IMPC and downregulates apoptosis in the cell clusters through activation of PI3K/Akt/Bcl-2 signaling. These results provide a convincing rationale for the high metastatic propensity seen in IMPC.

Invasive micropapillary carcinoma of the breast had no difference in prognosis compared with invasive ductal carcinoma: a propensity-matched analysis

Invasive micropapillary carcinoma (IMPC) is a rare histopathological variant of breast carcinoma that is usually associated with poor clinical characteristics. Whether IMPC has worse prognosis than invasive ductal carcinoma (IDC) is controversial. This retrospective study examined the prognostic difference between IMPC and IDC. We analysed 327 cases of IMPC patients and 4979 IDC cases who underwent primary resection in our institution between 2008 and 2012. Using propensity score matching, the two groups were matched at 1:1 by age, tumour size, nodal status, hormone status, and HER2 status. Differences in prognosis were assessed by Kaplan-Meier estimates and Cox regression analysis. We established the IMPC group and identified 324 IDC patients by propensity score matching. The survival analysis indicated that IMPC patients had no significant reduced overall survival (p = 0.752) or disease-free survival (p = 0.578) compared with IDC patients. Multivariate Cox regression analysis revealed that IMPC was not an independent prognostic factor for disease-free survival (hazard ratio [HR] = 0.944; 95% confidential interval [CI], 0.601–1.481) or overall survival (HR = 0.727; 95% CI, 0.358–1.478). Survival analysis demonstrated no statistically significant difference between IMPC and IDC, indicating that proactive or radical clinical therapy is unnecessary.

Nomogram for predicting preoperative lymph node involvement in patients with invasive micropapillary carcinoma of breast: a SEER population-based study

BACKGROUND

Invasive micropapillary carcinoma (IMPC) is an unusual and distinct subtype of invasive breast tumor with high propensity for regional lymph node metastases. This study was to identify risk factors accounting for IMPC of the breast and to develop a nomogram to preoperatively predict the probability of lymph node involvement.

METHODS

A retrospective review of the clinical and pathology records was performed in patients diagnosed with IMPC between 2003 and 2014 from Surveillance, Epidemiology, and End Results (SEER) database. The cohort was divided into training and validation sets. Training set comprised patients diagnosed between 2003 and 2009, while validation set included patients diagnosed thereafter. A logistic regression model was used to construct the nomogram in the training set and then varified in the validation set. Nomogram performance was quantified with respect to discrimination and calibration using R 3.4.1 software.

RESULTS

Overall, 1407 patients diagnosed with IMPC were enrolled, of which 527 in training set and 880 in validation set. Logistic regression analysis indicated larger lesions, younger age at diagnosis, black ethnic and lack of hormone receptor expression were significantly related to regional nodes involvement. The AUC of the nomogram was 0.735 (95% confidential interval (CI) 0.692 to 0.777), demonstrating a good prediction performance. Calibration curve for the nomogram was plotted and the slope was close to 1, which demonstrated excellent calibration of the nomogram. The performance of the nomogram was further validated in the validation set, with AUC of 0.748 (95% CI 0.701 to 0.767).

CONCLUSIONS

The striking difference between IMPC and IDC remains the increased lymph node involvement in IMPC and therefore merits aggressive treatment. The nomogram based on the clinicalpathologic parameters was established, which could accurately preoperatively predict regional lymph node status. This nomogram would facilitate evaluating lymph node state preoperatively and thus treatment decision-making of individual patients.

Diffusion-weighted MR imaging of locally advanced breast carcinoma: the optimal time window of predicting the early response to neoadjuvant chemotherapy

Background

It is very difficult to predict the early response to NAC only on the basis of change in tumor size. ADC value derived from DWI promises to be a valuable parameter for evaluating the early response to treatment. This study aims to establish the optimal time window of predicting the early response to neoadjuvant chemotherapy (NAC) for different subtypes of locally advanced breast carcinoma using diffusion-weighted imaging (DWI).

Methods

We conducted an institutional review board-approved prospective clinical study of 142 patients with locally advanced breast carcinoma. All patients underwent conventional MR and DW examinations prior to treatment and after first, second, third, fourth, sixth and eighth cycle of NAC. The response to NAC was classified into a pathologic complete response (pCR) and a non-pCR group. DWI parameters were compared between two groups, and the optimal time window for predicting tumor response was established for each chemotherapy regimen.

Results

For all the genomic subtypes, there were significant differences in baseline ADC value between pCR and non-pCR group (p < 0.05). The time point prior to treatment could be considered as the ideal time point regardless of genomic subtype. In the group that started with taxanes or anthracyclines, for Luminal A or Luminal B subtype, postT1 could be used as the ideal time point during chemotherapy; for Basal-like or HER2-enriched subtype, postT2 as the ideal time point during chemotherapy. In the group that started with taxanes and anthracyclines, for HER2-enriched, Luminal B or Basal-like subtype, postT1 could be used as the ideal time point during chemotherapy; for Luminal A subtype, postT2 as the ideal time point during chemotherapy.

Conclusions

The time point prior to treatment can be considered as the optimal time point regardless of genomic subtype. For each chemotherapy regimen, the optimal time point during chemotherapy varies across different genomic subtypes.

Decreased background parenchymal enhancement of the contralateral breast after two cycles of neoadjuvant chemotherapy is associated with tumor response in HER2-positive breast cancer

Background Several recent studies have focused on the association between background parenchymal enhancement (BPE) and tumor response to neoadjuvant chemotherapy (NAC), but early prediction of tumor response based on BPE has yet not been investigated. Purpose To retrospectively investigate whether changes in the BPE of the contralateral breast following NAC could help predict tumor response in early stage HER2-positive breast cancer. Material and Methods Data from 71 patients who were diagnosed with unilateral HER2 positive breast cancer and then underwent NAC with trastuzumab before surgery were analyzed retrospectively. Two experienced radiologists independently categorized the patients' levels of BPE of the contralateral breast into four categories (1 = minimal, 2 = mild, 3 = moderate, 4 = marked) at baseline and after the second cycle of NAC. After undergoing surgery, 34 patients achieved pathologic complete response (pCR) and 37 patients had residual disease (non-pCR). The association between BPE and histopathologic tumor response was analyzed. Result The level of BPE was higher in premenopausal than post-menopausal women both at baseline and after the second cycle of NAC ( P < 0.005). A significant reduction in BPE ( P < 0.001) was observed after the second NAC cycle; however, a more obvious decrease in BPE was identified in premenopausal relative to post-menopausal women ( P = 0.041). No significant association was identified between pCR and baseline BPE ( P = 0.287). However, after the second NAC cycle, decreased BPE was significantly associated with pCR ( P = 0.003). Conclusion For HER2-positive patients, changes in BPE may serve as an additional imaging biomarker of treatment response at an early stage.

Precise pathologic diagnosis and individualized treatment improve the outcomes of invasive micropapillary carcinoma of the breast: a 12-year prospective clinical study

Invasive micropapillary carcinoma of the breast is a histologic subtype of breast cancer and associated with high incidence of lymphovascular invasion, lymph node metastasis and poor prognosis. The aim of this prospective study was to investigate the impact of precise pathologic diagnosis and individualized treatment on the outcomes of invasive micropapillary carcinoma of the breast. The study group included 2299 women with invasive micropapillary carcinoma diagnosed at Tianjin Medical University Cancer Institute and Hospital between January 2004 and December 2015. In the study group, specimens were examined with the method of whole-specimen orientation and serial sectioning, and patients received precise pathological diagnosis and individualized treatment. The control group of invasive micropapillary carcinoma consisted of 163 cases, identified through a retrospectively review of 9056 invasive carcinomas diagnosed at our institution between January 1989 and December 2003 using the standard pathology-evaluation method (i.e., not using the whole-specimen orientation and serial-sectioning method). The clinicopathological features, treatments and outcomes were compared between the two groups. The incidence of invasive micropapillary carcinoma in the study group was 6% (2299/39,714 cases), significantly higher than that of the control group (2%; 163/9056 cases). The 5-year disease-free survival in the study group was significantly higher than that in the control group (83.8 vs.45.4%; p < 0.05). The 5-year overall survival was significantly increased from 57.4% in the control group to 90.9% in the study group (p < 0.05). In the multivariate analysis, lymphovascular invasion, estrogen receptor status and lymph node metastasis were independent prognostic factors. Although invasive micropapillary carcinoma of the breast is associated with poor prognosis, precise pathologic diagnosis and individualized treatment improved the disease-free survival and overall survival of invasive micropapillary carcinoma patients. Precise pathological diagnosis is the premises for individualized treatments and for improving the outcomes of patients with invasive micropapillary carcinoma of the breast.

Clinicopathologic study of invasive micropapillary carcinoma of the breast

Invasive micropapillary carcinoma (IMPC) is a rare subtype of breast carcinoma. It is presumed to be more aggressive than invasive ductal carcinoma (IDC), though it is uncertain whether the prognoses of IMPC and IDC differ. In this retrospective study, we compared the clinicopathologic characteristics and survival between 170 female patients with IMPC (pure or mixed with IDC) and 728 with pure IDC. The IMPC patients had higher clinical stages and histologic grades, higher incidences of lymphovascular invasion and axillary lymph node extracapsular extension, and a higher degree of lymph node involvement than IDC patients. Moreover, IMPC was associated with increases in estrogen receptor (ER) and progesterone receptor (PR) positivity and HER-2 overexpression. Although locoregional recurrence-free survival (LRRFS) and recurrence-free survival (RFS) were poorer in IMPC patients than IDC patients, overall survival and distant metastasis survival did not differ between the two groups. Multivariate analysis revealed that IMPC was an independent prognostic factor for LRRFS in breast cancer, and IMPC patients had poorer clinicopathologic characteristics and poorer RFS and LRRFS than IDC patients. We therefore suggest that to improve treatment decisions, patients with breast carcinoma be tested for the presence of this specific subtype.

The prognosis of invasive micropapillary carcinoma compared with invasive ductal carcinoma in the breast: a meta-analysis

Background

Invasive micropapillary carcinoma (IMPC) of the breast is a rare variant of invasive ductal carcinoma (IDC). The prognosis of IMPC compared with that of IDC remains controversial; we conducted a meta-analysis to evaluate the prognostic difference between IMPC and IDC.

Methods

We searched the PubMed, Cochrane Library, and EMBASE databases for relevant studies comparing overall survival (OS), disease-specific survival (DSS), relapse-free survival (RFS), local-regional recurrence-free survival (LRRFS) or distant metastasis-free survival (DMFS) rates between IMPC and IDC. Fixed-effect and random-effect models were utilized based on the heterogeneity of the eligible studies. Heterogeneity was further evaluated by subgroup and sensitivity analyses.

Results

Fourteen studies with 1888 IMPC patients were included in the meta-analysis. The summarized odds ratio (OR) and 95% confidence interval (95% CI) was calculated to estimate the prognostic difference between IMPC and IDC. IMPC patients showed an unfavorable prognosis for RFS (OR; 2.04; 95% CI: 1.63–2.55) and LRRFS (OR: 2.82; 95% CI: 1.90–4.17) compared with IDC. However, no significant difference was observed in OS (OR: 0.93; 95% CI: 0.78–1.10), DSS (OR: 1.16; 95% CI: 0.95–1.40) and DMFS (OR: 0.95; 95% CI: 0.67–1.35) between IMPC and IDC. No obvious statistical heterogeneity was detected, except for DSS. Funnel plots and Egger’s tests did not reveal publication bias, except for RFS.

Conclusions

This analysis showed that IMPC patients have a higher rate of loco-regional recurrence than IDC patients. However, OS, DSS and DMFS were not significantly different between IMPC and IDC. These results could help clinicians select therapeutic and follow-up strategies for IMPC patients.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3855-7) contains supplementary material, which is available to authorized users.

Postoperative radiotherapy for invasive micropapillary carcinoma of the breast: an analysis of Surveillance, Epidemiology, and End Results database

Introduction

Invasive micropapillary carcinoma (IMPC) of the breast poses a high risk of locoregional recurrence, and postoperative radiotherapy (PORT) may be beneficial in IMPC. Hence, we determined the clinical value of PORT in IMPC patients.

Patients and methods

We assessed clinicopathological factors extracted from the Surveillance, Epidemiology, and End Results database (2004–2013). Univariate and multivariate Cox proportional hazards regressions were performed to assess the independent prognostic factors on breast cancer-specific survival (BCSS) and overall survival (OS).

Results

Of the 881 study patients, 444 (50.4%) and 437 (49.6%) underwent breast-conserving surgery (BCS) and mastectomy (MAST), respectively, of whom 357 (80.4%) and 153 (35.0%) underwent PORT, respectively. Patients with young age, large tumor size, or advanced nodal stage were more likely to undergo MAST and PORT compared with MAST alone. Patients with progesterone receptor-positive disease were more likely to receive BCS and PORT compared with BCS alone. The 5-year BCSS and OS were 95.7% and 90.9%, respectively. On multivariate analyses, tumor size, histological grade, and estrogen receptor status were independent predictors of BCSS and OS. The types of surgical procedures (MAST vs. BCS) were not an independent predictor of survival outcomes. Patients who underwent MAST with or without PORT had similar BCSS and OS in the multivariate analyses. Those who underwent BCS plus PORT did not have better BCSS and OS than those who underwent BCS alone. In the low-, intermediate-, and high-risk groups, PORT was not associated with better BCSS and OS than non-PORT groups in patients who received BCS or MAST.

Conclusion

IMPC has favorable BCSS and OS. Regardless of the types of surgical procedures (MAST or BCS), PORT groups were not inferior to non-PORT groups on BCSS and OS.

Invasive Micropapillary Carcinoma of the Breast: An Update

CONTEXT

-Invasive micropapillary carcinoma (IMPC) is a distinct variant of mammary carcinoma in which tumor cells are arranged in morulelike clusters devoid of fibrovascular cores and situated within empty stromal spaces. Identification of IMPC can be achieved by the assessment of morphologic features in conjunction with the characteristic "inside-out" staining pattern of epithelial membrane antigen and sialyl Lewis X highlighted by immunohistochemical analysis. Although recognizing micropapillary architecture is often not challenging, the criteria for distinguishing between mixed and pure IMPC remain imprecise. Some mucin-producing carcinomas can also have micropapillary histology, but there is no consensus on whether these tumors are variants of IMPC or mucinous carcinomas. The molecular genetic studies demonstrate that IMPCs have distinct molecular genetic profiles, supporting the theory that they constitute distinct pathologic entities. However, genomic analyses have not identified any specific genomic aberration that may explain the distinctive morphology and clinical behavior of IMPC.

OBJECTIVE

-To provide an overview on the current concepts in the diagnosis and pathogenesis of IMPC of the breast, incorporating recent molecular genetic advances and prognosis-based reclassification.

DATA SOURCES

-PubMed search and the cited references were reviewed.

CONCLUSIONS

-The recent evolution of prognosis-based reclassification and molecular genetic advances has enhanced our knowledge of the pathogenesis of IMPC of the breast. Additional studies might reveal consistent molecular alterations that underlie the formation of the inside-out growth pattern, and they might elucidate the molecular mechanisms responsible for the unfavorable clinical behavior of IMPC.

18F-fluorodeoxyglucose (FDG) PET/CT after two cycles of neoadjuvant therapy may predict response in HER2-negative, but not in HER2-positive breast cancer

The aim of this prospective study was to assess the ability of 18F-fluorodeoxyglucose (¹⁸FDG) positron emission tomography/computed tomography (PET/CT) scanning to predict pathological complete response (pCR) in breast cancer, and to investigate whether timing of the scan and trastuzumab treatment influence the accuracy of pCR prediction in human epidermal growth factor receptor 2 (HER2) positive breast cancer patients. We treated 81 locally advanced breast cancer patients with four cycles of neoadjuvant chemotherapy (NAC). HER2-negative breast cancer patients received NAC alone, while HER2-positive breast cancer patients received NAC plus trastuzumab. ¹⁸FDG PET/CT scans were scheduled at baseline and after the second cycle of NAC. Axillary lymph node (ALN) dissection was performed after the last cycle of neoadjuvant therapy. Relative changes in standardized uptake values (SUV) between the two PET/CT scans (ΔSUV) in primary tumors and ALN metastases were calculated. There were 75 patients with 150 PET/CT scans in the final analysis, including 41 HER2-negative and 34 HER2-positive cases. In the HER2-negative group, the ΔSUV predicted overall and ALN pCR; the receiver operating characteristics-areas under curve (ROC-AUC) were 0.87 and 0.80 (P = 0.0014 and 0.031, respectively) and the negative predictive values were 94% and 89% respectively. However, in the HER2-positive group, ΔSUV could predict neither overall nor ALN pCR; the ROC-AUCs were only 0.56 and 0.53, with P = 0.53 and 0.84, respectively. Hence, the ΔSUV after two cycles of neoadjuvant therapy could predict pCR in HER2-negative patients treated with NAC alone, but not in HER2-positive patients treated with NAC plus trastuzumab.

Invasive micropapillary carcinoma of the breast had poor clinical characteristics but showed no difference in prognosis compared with invasive ductal carcinoma

Background

It is controversial for prognosis of invasive micropapillary carcinoma (IMPC) compared with invasive ductal carcinoma (IDC) of the breast. To better understand the difference between IMPC and IDC prognoses, we conducted this retrospective study.

Methods

Data from 33 patients with IMPC were retrospectively reviewed, and the clinicopathologic characteristics and survival status were compared with those of 347 patients with IDC who were treated during the same period.

Results

The IMPC cases were of larger tumor size, greater proportion of nodal involvement, and an increased incidence of lymphovascular invasion compared with IDC cases. The overall survival (OS), local relapse-free survival (LRFS), distant metastasis-free survival (DMFS), and failure-free survival (FFS) rates were not significantly different between IMPC and IDC. The 3-year OS rate was 97 vs 94.2 % for the IMPC and IDC patients, respectively. The 3-year FFS rate was 87.9 vs 86.2 % for the IMPC and IDC patients, respectively. For IMPC patients, the 3-year LRFS rate was 93.9 % and in IDC patients was 89.0 %. The 3-year DMFS rates of IMPC patients was 90.9 % and IDC patients was 89 %.

Conclusions

IMPC had poor clinical characteristics, but it showed no difference in OS, FFS, LRFS, and DMFS compare with IDC.