Prognostic implications of lobular breast cancer histology: new insights from a single hospital cross-sectional study and SEER data

A role for breast ultrasound Artificial Intelligence decision support in the evaluation of small invasive lobular carcinomas

OBJECTIVE

To evaluate the diagnostic performance of an Artificial Intelligence (AI) decision support (DS) system in the ultrasound (US) assessment of invasive lobular carcinoma (ILC) of the breast, a cancer that can demonstrate variable appearance and present insidiously.

METHODS

Retrospective review was performed of 75 patients with 83 ILC diagnosed by core biopsy or surgery between November 2017 and November 2019. ILC characteristics (size, shape, echogenicity) were recorded. AI DS output (lesion characteristics, likelihood of malignancy) was compared to radiologist assessment.

RESULTS

The AI DS system interpreted 100% of ILCs as suspicious or probably malignant (100% sensitivity, and 0% false negative rate). 99% (82/83) of detected ILCs were initially recommended for biopsy by the interpreting breast radiologist, and 100% (83/83) were recommended for biopsy after one additional ILC was identified on same-day repeat diagnostic ultrasound. For lesions in which the AI DS output was probably malignant, but assigned a BI-RADS 4 assessment by the radiologist, the median lesion size was 1 cm, compared with a median lesion size of 1.4 cm for those given a BI-RADS 5 assessment (p = 0.006). These results suggest that AI may offer more useful DS in smaller sub-centimeter lesions in which shape, margin status, or vascularity is more difficult to discern. Only 20% of patients with ILC were assigned a BI-RADS 5 assessment by the radiologist.

CONCLUSION

The AI DS accurately characterized 100% of detected ILC lesions as suspicious or probably malignant. AI DS may be helpful in increasing radiologist confidence when assessing ILC on ultrasound.

Molecular analysis of TCGA breast cancer histologic types

Breast cancer is classified into multiple distinct histologic types, and many of the rarer types have limited characterization. Here, we extend The Cancer Genome Atlas Breast Cancer (TCGA-BRCA) dataset with additional histologic type annotations, in a total of 1063 breast cancers. We analyze this extended dataset to define transcriptomic and genomic profiles of six rare special histologic types: cribriform, micropapillary, mucinous, papillary, metaplastic, and invasive carcinoma with medullary pattern. We show the broader applicability of our constructed special histologic type gene signatures in the TCGA Pan-Cancer Atlas dataset with a predictive model that detects mucinous histologic type across cancers of other organ systems. Using a normal mammary cell differentiation score analysis, we order histologic types into a continuum from stem cell-like to luminal progenitor-like to mature luminal-like. Finally, we classify TCGA-BRCA into 12 consensus groups based on integrated genomic and histological features. We present a rich openly accessible resource of histologic and genomic characterization of TCGA-BRCA to enable studies of the range of breast cancers.

A Comparison of the Clinicopathological Features, Metastasis Sites and Survival Outcomes of Invasive Lobular, Invasive Ductal and Mixed Invasive Ductal and Lobular Breast Carcinoma

Objective

We compared the breast cancer patients with invasive lobular carcinoma (ILC), invasive ductal carcinoma (IDC) and mixed invasive ductal and lobular carcinoma (IDLC) in terms of clinicopathological and treatment features, metastatic patterns and long-term survival.

Materials and Methods

In a 10 years patient cohort, 3412 patients with unilateral breast carcinoma were enrolled in the study. Tumors were classified histologically according to criteria described by World Health Organization classification.

Results

The highest rate of T3 tumors were found in IDLC patients, the lowest in IDC patients, and the difference between groups was significant only in comparison of IDC vs IDLC. Axillary positivity rate was highest in IDLC, lowest in ILC; differences were significant in comparisons of IDLC vs ILC and IDLC vs IDC. There was no significant difference between the patient groups in terms of surgical treatment, mastectomy and breast conserving surgery. Rate of bone metastasis was highest in IDLC, lowest in IDC, with significant difference between IDLC and IDC. Locoregional recurrence-free survival (LRFS) rate was 90.9% in ILC patients, 92.5% in IDC patients, 92.9% in IDLC patients, with no significant difference between the groups; in multivariate Cox analysis, histological type had no prognostic significance (p=0.599). Distant metastasis-free survival (DMFS) rate was 66.2% in ILC patients, 66.7% in IDC patients, 57.1% in IDLC patients; in multivariate Cox analysis, histological type had no prognostic significance (p=0.392).

Conclusion

Although these results suggest that IDLC may have a worse prognosis than IDC and ILC, in multivariate analysis LRFS and DMFS were not significantly different among the histological type groups.

Integrated molecular analysis of Tamoxifen-resistant invasive lobular breast cancer cells identifies MAPK and GRM/mGluR signaling as therapeutic vulnerabilities

Invasive lobular breast cancer (ILC) is an understudied malignancy with distinct clinical, pathological, and molecular features that distinguish it from the more common invasive ductal carcinoma (IDC). Mounting evidence suggests that estrogen receptor-alpha positive (ER+) ILC has a poor response to Tamoxifen (TAM), but the mechanistic drivers of this are undefined. In the current work, we comprehensively characterize the SUM44/LCCTam ILC cell model system through integrated analysis of gene expression, copy number, and mutation, with the goal of identifying actionable alterations relevant to clinical ILC that can be co-targeted along with ER to improve treatment outcomes. We show that TAM has several distinct effects on the transcriptome of LCCTam cells, that this resistant cell model has acquired copy number alterations and mutations that impinge on MAPK and metabotropic glutamate receptor (GRM/mGluR) signaling networks, and that pharmacological inhibition of either improves or restores the growth-inhibitory actions of endocrine therapy.

Invasive lobular carcinoma of the breast: A special histological type compared with invasive ductal carcinoma

The clinical outcomes and therapeutic strategies for infiltrating ductal carcinoma (IDC) and infiltrating lobular carcinoma (ILC) are not uniform. The primary objectives of this study were to identify the differences in the clinical characteristics and prognoses between ILC and IDC, and identify the high-risk population based on the hormone receptor status and metastasis sites. The Surveillance, Epidemiology, and End Results Program database was searched and patients diagnosed with ILC or IDC from 1990 to 2013 were identified. In total,796,335 patients were analyzed, including 85,048 withILC (10.7%) and 711,287 withIDC (89.3%). The ILC group was correlatedwith older age, larger tumor size, later stage, lower grade, metastasis disease(M1) disease, and greater counts ofpositive lymph nodesandestrogen-receptor-positive (ER)/progesterone receptor-positive (PR) positive nodes. The overall survival showed an early advantage for ILC but a worse outcome after 5 years. Regarding the disease-specific survival, the IDC cohort had advantages over the ILC group, both during the early years and long-term. In hormone status and metastasis site subgroup analyses, the ER+/PR+ subgroup had the best survival, while the ER+/PR- subgroup had the worst outcome, especially the ILC cohort. ILC and IDC had different metastasis patterns. The proportion of bone metastasis was higher in the ILC group (91.52%) than that in the IDC (76.04%), and the ILC group was more likely to have multiple metastasis sites. Survival analyses showed patients with ILC had a higher risk of liver metastasis (disease-specific survival[DSS]; P = 0.046), but had a better overall survival than the bone metastasis group (P<0.0001). We concluded that the long-term prognosis for ILC was poorer than that for IDC, and the ER+/PR- subgroup had the worst outcome. Therefore, the metastasis pattern and prognosis must be seriously evaluated, and a combination of endocrine therapy and chemotherapy should be considered.

Extended adjuvant endocrine therapy - A standard to all or some?

Patients with estrogen receptor-positive (ER +) early breast cancer (EBC) are at a continuous risk for distant relapse despite 5 years of standard endocrine therapy, even after 10-15 years after primary diagnosis. Hence, large randomized clinical trials were conducted to evaluate the role of extended endocrine treatment (ET) with the primary goal to prevent or at least delay distant relapse. Two very large trials of extended tamoxifen (TAM), the ATLAS and the aTTom trial, proved the efficacy of prolonged TAM particularly important after 10 years due to the carry-over effect of the five initial years. Additionally, the extended use of AIs after 5 years of tamoxifen, also proved to be efficacious in preventing late distant relapses. For letrozole (LET) it was shown in the MA.17 trial that it also improves overall survival (OS) in node-positive BC patients. There are many options and still unanswered questions related to extended ET, which are discussed in this review. The most important issue in deciding prolonged duration of ET is undoubtfully how to identify ER+ patients who benefit most from this approach. With this purpose, not only classical pathological factors have been studied, but also molecular profiles of individual tumors, which might help us in the near future to better tailor ET. Not only efficacy, but also toxicity of such prolonged treatment is essential for optimal use, particularly maintained compliance in a routine clinical practice. These issues are discussed in this review.