Validation of the IBIS breast cancer risk evaluator for women with lobular carcinoma in-situ

Individualizing Breast Cancer Risk Assessment in Clinical Practice

Multiple tools exist to assess a patient's breast cancer risk. The choice of risk model depends on the patient's risk factors and how the calculation will impact care. High-risk patients-those with a lifetime breast cancer risk of ≥20%-are, for instance, eligible for supplemental screening with breast magnetic resonance imaging. Those with an elevated short-term breast cancer risk (frequently defined as a 5-year risk ≥1.66%) should be offered endocrine prophylaxis. High-risk patients should also receive guidance on modification of lifestyle factors that affect breast cancer risk.

Breast Cancer Screening: An Overview of Risk-specific Screening and Risk Assessment

Breast cancer screening decreases stage at diagnosis, treatment morbidity, and disease mortality. A comprehensive risk assessment is critical to determine an individual's most appropriate screening regimen. Multiple guidelines exist for screening mammography in average-risk individuals, which differ on age and frequency of screening. Annual mammography starting at age 40 is associated with the greatest reduction in breast cancer mortality and greatest number of life-years saved. A formal risk calculator is helpful to assess one's lifetime risk of breast cancer and assess eligibility for high-risk screening. Screening guidelines exist for genetic mutations that increase breast cancer risk.

Accuracy of the Breast Cancer Surveillance Consortium Model Among Women with LCIS

PURPOSE

The Breast Cancer Surveillance Consortium (BCSC) model predicts risk of invasive breast cancer risk based on age, race, family history, breast density, and history of benign breast disease, including lobular carcinoma in situ (LCIS). However, validation studies for this model included few women with LCIS. We sought to evaluate the accuracy of the BCSC model among this cohort.

METHODS

Women with LCIS diagnosed between 1983 and 2017 were identified from a prospectively maintained database. The BCSC score was calculated; those with prior breast cancer, unknown breast density, age < 35 years or > 74 years, or with history of chemoprevention use were excluded. The Kaplan-Meier method was used to estimate incidence rates. Time-dependent receiver operating characteristic (ROC) analysis was used to analyze the discriminative capacity of the model.

RESULTS

1302 women with LCIS were included. At a median follow-up of 7 years, 152 women (12%) developed invasive cancer (6 with bilateral disease). Cumulative incidences of invasive breast cancer were 7.1% (95% CI 5.6-8.7) and 13.3% (95% CI 10.9-15.6), respectively, and the median BCSC risk scores were 4.9 and 10.4, respectively, at 5 and 10 years. The median 10-year BCSC score was significantly lower than the 10-year Tyrer-Cuzick score (10.4 vs 20.8, p < 0.001). The ROC curve scores (AUC) for BCSC at 5 and 10 years were 0.59 (95% CI 0.52-0.66) and 0.58 (95% CI 0.52-0.64), respectively.

CONCLUSION

The BCSC model has moderate accuracy in predicting invasive breast cancer risk among women with LCIS with fair discrimination for risk prediction between individuals.

Lobular Breast Cancer: Histomorphology and Different Concepts of a Special Spectrum of Tumors

Simple Summary

Invasive lobular breast cancer (ILC) is a special type of breast cancer (BC) that was first described in 1941. The diagnosis of ILC is made by microscopy of tumor specimens, which reveals a distinct morphology. This review recapitulates the developments in the microscopic assessment of ILC from 1941 until today. We discuss different concepts of ILC, provide an overview on ILC variants, and highlight advances which have contributed to a better understanding of ILC as a special histologic spectrum of tumors.

Abstract

Invasive lobular breast cancer (ILC) is the most common special histological type of breast cancer (BC). This review recapitulates developments in the histomorphologic assessment of ILC from its beginnings with the seminal work of Foote and Stewart, which was published in 1941, until today. We discuss different concepts of ILC and their implications. These concepts include (i) BC arising from mammary lobules, (ii) BC growing in dissociated cells and single files, and (iii) BC defined as a morpho-molecular spectrum of tumors with distinct histological and molecular characteristics related to impaired cell adhesion. This review also provides a comprehensive overview of ILC variants, their histomorphology, and differential diagnosis. Furthermore, this review highlights recent advances which have contributed to a better understanding of the histomorphology of ILC, such as the role of the basal lamina component laminin, the molecular specificities of triple-negative ILC, and E-cadherin to P-cadherin expression switching as the molecular determinant of tubular elements in CDH1-deficient ILC. Last but not least, we provide a detailed account of the tumor microenvironment in ILC, including tumor infiltrating lymphocyte (TIL) levels, which are comparatively low in ILC compared to other BCs, but correlate with clinical outcome. The distinct histomorphology of ILC clearly reflects a special tumor biology. In the clinic, special treatment strategies have been established for triple-negative, HER2-positive, and ER-positive BC. Treatment specialization for patients diagnosed with ILC is just in its beginnings. Accordingly, ILC deserves greater attention as a special tumor entity in BC diagnostics, patient care, and cancer research.

Updates on Lobular Neoplasms, Papillary, Adenomyoepithelial, and Fibroepithelial Lesions of the Breast

CONTEXT.—

This review article is a result of the breast pathology lectures given at the Sixth Chinese American Pathologists Association annual diagnostic pathology course in October 2020 (held virtually due to the coronavirus disease 2019).

OBJECTIVE.—

To update recent developments, in this review article, the authors wrote minireviews in the following 4 areas: lobular neoplasm, adenomyoepithelial lesions, papillary lesions, and fibroepithelial lesions.

DATA SOURCES.—

The sources include extensive literature review, personal research, and experience.

CONCLUSIONS.—

With the wide practice of screening mammography, these lesions are not uncommon in image-guided core biopsies and excisional specimens. Many recent developments have emerged in understanding these lesions. We aim to provide readers with concise updates for each of these lesions with a focus on recent updates in definitions, diagnostic criteria, management, and molecular profiles that are most relevant to the daily practice of pathology and patient management.

Towards a more precise and individualized assessment of breast cancer risk

Many clinically based models are available for breast cancer risk assessment; however, these models are not particularly useful at the individual level, despite being designed with that intent. There is, therefore, a significant need for improved, precise individualized risk assessment. In this Research Perspective, we highlight commonly used clinical risk assessment models and recent scientific advances to individualize risk assessment using precision biomarkers. Genome-wide association studies have identified >100 single nucleotide polymorphisms (SNPs) associated with breast cancer risk, and polygenic risk scores (PRS) have been developed by several groups using this information. The ability of a PRS to improve risk assessment is promising; however, validation in both genetically and ethnically diverse populations is needed. Additionally, novel classes of biomarkers, such as microRNAs, may capture clinically relevant information based on epigenetic regulation of gene expression. Our group has recently identified a circulating-microRNA signature predictive of long-term breast cancer in a prospective cohort of high-risk women. While progress has been made, the importance of accurate risk assessment cannot be understated. Precision risk assessment will identify those women at greatest risk of developing breast cancer, thus avoiding overtreatment of women at average risk and identifying the most appropriate candidates for chemoprevention or surgical prevention.

Breast cancer prevention in high-risk women

Women at high risk of developing breast cancer are a heterogeneous group of women including those with and without high-risk germline mutation/s. Prevention in these women requires a personalised and multidisciplinary approach. Preventive therapy with selective oestrogen receptor modulators (SERMs) like tamoxifen and aromatase inhibitors (AIs) substantially reduces breast cancer risk well beyond the active treatment period. The importance of benign breast disease as a marker of increased breast cancer risk remains underappreciated, and although the benefit of preventive therapy may be greater in such women, preventive therapy remains underutilised in these and other high-risk women. Bilateral Risk-Reducing Mastectomy (BRRM) reduces the risk of developing breast cancer by 90% in high-risk women such as carriers of BRCA mutations. It also improves breast cancer-specific survival in BRCA1 carriers. Bilateral risk-reducing salpingo-oophorectomy may also reduce risk in premenopausal BRCA2 carriers. Further research to improve risk models, to identify surrogate biomarkers of preventive therapy benefit and to develop newer preventive agents is needed.

The Tyrer-Cuzick Model Inaccurately Predicts Invasive Breast Cancer Risk in Women With LCIS

BACKGROUND

The Tyrer-Cuzick model has been shown to overestimate risk in women with atypical hyperplasia, although its accuracy among women with lobular carcinoma in situ (LCIS) is unknown. We evaluated the accuracy of the Tyrer-Cuzick model for predicting invasive breast cancer (IBC) development among women with LCIS.

METHODS

Women with LCIS participating in surveillance from 1987 to 2017 were identified from a prospectively maintained database. Tyrer-Cuzick score (version 7) was calculated near the time of LCIS diagnosis. Patients with prior or concurrent breast cancer, a BRCA mutation, receiving chemoprevention, or with pleomorphic LCIS were excluded. Invasive cancer-free probability was estimated using the Kaplan-Meier method.

RESULTS

A total of 1192 women with a median follow-up of 6 years (interquartile range [IQR] 2.5-9.9) were included. Median age at LCIS diagnosis was 49 years (IQR 45-55), 88% were white; 37% were postmenopausal, 28% had ≥ 1 first-degree family member with breast cancer, and 13% had ≥ 2 second-degree family members with breast cancer. In total, 128 patients developed an IBC; median age at diagnosis was 54 years (IQR 49-61). Five- and 10-year cumulative incidences of invasive cancer were 8% (95% confidence interval [CI] 6-9%) and 14% (95% CI 12-17%), respectively. The median Tyrer-Cuzick 10-year risk score was 20.1 (IQR 17.4-24.3). Discrimination measured by the C-index was 0.493, confirming that the Tyrer-Cuzick model is not well calibrated in this patient population.

CONCLUSIONS

The Tyrer-Cuzick model is not accurate and may overpredict IBC risk for women with LCIS, and therefore should not be used for breast cancer risk assessment in this high-risk population.