Early Breast Cancer Precursor Lesions: Lessons Learned from Molecular and Clinical Studies

Intercepting Premalignant, Preinvasive Breast Lesions Through Vaccination

Breast cancer (BC) prevention remains the ultimate cost-effective method to reduce the global burden of invasive breast cancer (IBC). To date, surgery and chemoprevention remain the main risk-reducing modalities for those with hereditary cancer syndromes, as well as high-risk non-hereditary breast lesions such as ADH, ALH, or LCIS. Ductal carcinoma in situ (DCIS) is a preinvasive malignant lesion of the breast that closely mirrors IBC and, if left untreated, develops into IBC in up to 50% of lesions. Certain high-risk patients with DCIS may have a 25% risk of developing recurrent DCIS or IBC, even after surgical resection. The development of breast cancer elicits a strong immune response, which brings to prominence the numerous advantages associated with immune-based cancer prevention over drug-based chemoprevention, supported by the success of dendritic cell vaccines targeting HER2-expressing BC. Vaccination against BC to prevent or interrupt the process of BC development remains elusive but is a viable option. Vaccination to intercept preinvasive or premalignant breast conditions may be possible by interrupting the expression pattern of various oncodrivers. Growth factors may also function as potential immune targets to prevent breast cancer progression. Furthermore, neoantigens also serve as effective targets for interception by virtue of strong immunogenicity. It is noteworthy that the immune response also needs to be strong enough to result in target lesion elimination to avoid immunoediting as it may occur in IBC arising from DCIS. Overall, if the issue of vaccine targets can be solved by interrupting premalignant lesions, there is a potential to prevent the development of IBC.

Upgrade rates and outcomes of screen-detected atypical intraductal epithelial proliferation (AIDEP) diagnosed on core needle biopsy

INTRODUCTION

Atypical intraductal epithelial proliferation (AIDEP) is a breast lesion categorised as "indeterminate" if identified on core needle biopsy (CNB). The rate at which these lesions are upgraded following diagnostic excision varies in the literature. Women diagnosed with AIDEP are thought to be at increased risk of breast cancer. Our aim was to identify the rate of upgrade to invasive or in situ carcinoma in a group of patients diagnosed with AIDEP on screening mammography and to quantify their risk of subsequent breast cancer.

METHODS

We conducted a retrospective review of a prospectively maintained database containing all patients diagnosed with AIDEP on CNB between 2005 and 2012 in an Irish breast screening centre. Basic demographic data was collected along with details of the original CNB result, rate of upgrade to carcinoma and details of any subsequent cancer diagnoses.

RESULTS

In total 113 patients were diagnosed with AIDEP on CNB during the study period. The upgrade rate on diagnostic excision was 28.3% (n = 32). 6.2% (n = 7) were upgraded to invasive cancer and 22.1% (n = 25) to DCIS. 81 patients were not upgraded on diagnostic excision and were offered 5 years of annual mammographic surveillance. 9.88% (8/81) of these patients went on to receive a subsequent diagnosis of malignancy. The mean time to diagnosis of these subsequent cancers was 65.41 months (range 20.18-145.21).

CONCLUSION

Our data showing an upgrade rate of 28% to carcinoma reflects recently published data and we believe it supports the continued practice of excising AIDEP to exclude co-existing carcinoma.

Machine learning-based image analysis for accelerating the diagnosis of complicated preneoplastic and neoplastic ductal lesions in breast biopsy tissues

PURPOSE

Diagnosis of breast preneoplastic and neoplastic lesions is difficult due to their similar morphology in breast biopsy specimens. To diagnose these lesions, pathologists perform immunohistochemical analysis and consult with expert breast pathologists. These additional examinations are time-consuming and expensive. Artificial intelligence (AI)-based image analysis has recently improved, and may help in ordinal pathological diagnosis. Here, we showed the significance of machine learning-based image analysis of breast preneoplastic and neoplastic lesions for facilitating high-throughput diagnosis.

METHODS

Images were obtained from normal mammary glands, hyperplastic lesions, preneoplastic lesions and neoplastic lesions, such as usual ductal hyperplasia (UDH), columnar cell lesion (CCL), ductal carcinoma in situ (DCIS), and DCIS with comedo necrosis (comedo DCIS) in breast biopsy specimens. The original enhanced convoluted neural network (CNN) system was used for analyzing the pathological images.

RESULTS

The AI-based image analysis provided the following area under the curve values (AUC): normal lesion versus DCIS, 0.9902; DCIS versus comedo DCIS, 0.9942; normal lesion versus CCL, 0.9786; and UDH versus DCIS, 1.000. Multiple comparison analysis showed precision and recall scores similar to those of single comparison analysis. Based on the gradient-weighted class activation mapping (Grad-CAM) used to visualize the important regions reflecting the result of CNN analysis, the ratio of stromal tissue in the whole weighted area was significantly higher in UDH and CCL than that in DCIS.

CONCLUSIONS

These analyses may provide a more accurate and rapid pathological diagnosis of patients. Moreover, Grad-CAM identifies uncharted important histological characteristics for newer pathological findings and targets of research for understanding diseases.

Canine mammary tumours: Size matters-a progression from low to highly malignant subtypes

The purpose of this study was to evaluate a possible association between mammary tumour size and increasing degree of malignancy. Data of 625 dogs with a total of 1459 mammary tumours were analysed retrospectively. 80.3% dogs were intact, mean age at diagnosis was 9.7 ± 2.5 years, 75.8% were pure breed dogs. Median body weight was 20.0 kg. Malignant tumours (n = 580) were significantly larger than their benign counterparts (1.94 cm vs 0.90 cm in mean, respectively; P ≤ .0001), resulting in a positive correlation between increasing tumour size and a change from benign to malignant (P ≤ .0001; r_s  = 0.214). When malignant tumours were grouped into four degrees of increasing malignancy (complex/simple/solid/anaplastic carcinomas) a significant positive correlation between increasing tumour size and more malignant tumour degree (P ≤ .0001; r_s  = 0.195) could be demonstrated. In a number of cases, highly malignant tumours were found to arise within less malignant lesions, supporting the concept of a further progression within the malignant tumour subtypes. In patients with multiple tumours, mean tumour sizes for malignant tumours were significantly smaller compared to patients with only one tumour (1.67 vs 2.71 cm in mean, respectively; P < .0001). These findings suggest that mammary tumours progress not only from benign to malignant but also from low to highly malignant. An increase in diameter of only a few millimetres may therefore have a big impact on the patient's outcome.

Benign Breast Disease in Women

BACKGROUND

Most clinical breast changes in women are benign; in only 3% to 6% of cases are they due to breast cancer. How- ever, there is a lack of up-to-date, evidence-based treatment recommendations for the various benign differential diagnoses.

METHODS

Selective literature search of PubMed from 1985 to May 2019, including current national (AWMF, Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften [Association of Scientific Medical Societies in Germany]) and inter- national guidelines.

RESULTS

Mastalgia and fibrocystic changes are common (around 50% of all women over the age of 30). Fibroadenomas occur in 25% of women; they are the most common benign tumors of the breast and do not require treatment. With most benign breast changes the risk of dedifferentiation is very low. However, it is important in the differential diagnosis to distinguish between such benign changes and breast cancer or changes that carry a risk of malignancy. Complex cysts, for example, carry a risk of malig- nancy of 23% to 31%, papillary lesions 16% , and radial scars 7%. Where there is doubt, histological confirmation should be sought by means of percutaneous biopsy.

CONCLUSION

Benign breast changes can be definitively distinguished from malignant lesions through the selective use of avail- able diagnostic investigations and interdisciplinary collaboration. When lesions of uncertain malignant potential are found (B3 in the biopsy classification), complete excision is indicated. Prospective studies on the early diagnosis of breast cancer in lesions carrying a risk of malignancy are desirable.

Multi-targeting chemoprevention of Chinese herb formula Yanghe Huayan decoction on experimentally induced mammary tumorigenesis

BACKGROUND

Development of safe and effective chemopreventive agents is a winning strategy in reducing the morbidity and mortality of breast cancer. The current study was to investigate the mechanism-based chemopreventive potential of a Chinese herb formula Yanghe Huayan (YHHY) Decoction on the classical 7,12-dimethylbenz(a)anthracene (DMBA) induced rat mammary carcinogenesis model.

METHODS

Female Sprague-Dawley rats at 42 days of age were orally administered with a human equivalent dose of YHHY Decoction at 0.02 ml/g (10 mg/ml) once daily, starting 1 wk. before and 4 wks following DMBA treatment. Mammary tumor occurrence was monitored every day. The length of time before palpable tumor is examined is defined as tumor-free survival time. High performance liquid chromatography (HPLC) analyses were adopted to identify major chemical compositions of the decoction. Following bioinformatics data mining and experimental analyses were performed to demonstrate the underlying mechanism of action.

RESULTS

DMBA animals receiving YHHY Decoction exhibited a significant delay (P = 0.014) and in some animals prevention (P = 0.046) of tumor occurrence without obvious toxicity. Oncogenic myc activation was significantly suppressed in the DMBA-induced rats by the YHHY treatment. Eight major chemical compositions of the decoction were identified and were shown to interfere with multiple tumorigenic pathways simultaneously in the mammary tumors, including inducing tumor apoptosis and up-regulating pro-apoptotic protein Bax and down-regulating anti-apoptotic protein Bcl-2; suppressing abnormal cell proliferation and the MAPK/ERK, PI3K/AKT signalings; blocking neo-angiogenesis and the VEGF/KDR signaling, and inhibiting oxidative stress in the mammary tumors.

CONCLUSION

The multi-components and multi-targeting properties of the YHHY Decoction support its use as a potent chemopreventive drug in breast cancer.

Reviewing the Evidence to Guide Clinical Care: Proliferative Breast Lesions in Breast Reduction Specimens

The number of reduction mammoplasties performed in the United States continues to increase annually. Given the high incidence of breast cancer in women, it is routine practice for breast tissue excised during routine breast reductions procedures to be sent for pathology review. During pathology assessment, occult malignancy and on-occasion proliferative breast lesions of unknown and/or variable malignancy may also be present. We provide a review of commonly diagnosed atypical proliferative breast lesions in breast reduction specimens and a guide to plastic surgeons for further management.

Progressive polarity loss and luminal collapse disrupt tissue organization in carcinoma

Epithelial cancers (carcinoma) account for 80%-90% of all cancers. The development of carcinoma is associated with disrupted epithelial organization and solid ductal structures. The mechanisms underlying the morphological development of carcinoma are poorly understood, but it is thought that loss of cell polarity is an early event. Here we report the characterization of the development of human breast lesions leading to carcinoma. We identified a unique mechanism that generates solid ducts in carcinoma through progressive loss of polarity and collapse of the luminal architecture. This program initiates with asymmetric divisions of polarized cells that generate a stratified epithelium containing both polarized and depolarized cells. Stratified regions form cords that penetrate into the lumen, subdividing it into polarized secondary lumina. The secondary lumina then collapse with a concomitant decrease in RhoA and myosin II activity at the apical membrane and ultimately lose apical-basal polarity. By restoring RhoA activity in mice, ducts maintained lumen and cell polarity. Notably, disrupted tissue architecture through luminal collapse was reversible, and ducts with a lumen were re-established after oncogene suppression in vivo. This reveals a novel and common mechanism that contributes to carcinoma development by progressively disrupting cell and tissue organization.

Aberrant Proliferation of Differentiating Alveolar Cells Induces Hyperplasia in Resting Mammary Glands of SV40-TAg Transgenic Mice

WAP-T1 transgenic mice express SV40-TAg under control of the whey acidic protein (WAP) promoter, which directs activity of this strong viral oncogene to luminal cells of the mammary gland. Resting uniparous WAP-T1 glands develop hyperplasia composed of TAg positive cells prior to appearance of advanced tumor stages. We show that cells in hyperplasia display markers of alveolar differentiation, suggesting that TAg targets differentiating cells of the alveolar compartment. The glands show significant expression of Elf5 and milk genes (Lalba, Csn2, and Wap). TAg expressing cells largely co-stain with antibodies to Elf5, lack the epithelial marker Sca1, and are hormone receptor negative. High expression levels of Elf5 but not of milk genes are also seen in resting glands of normal BALB/c mice. This indicates that expression of Elf5 in resting WAP-T1 glands is not specifically induced by TAg. CK6a positive luminal cells lack TAg. These cells co-express the markers prominin-1, CK6a, and Sca1, and are positive for hormone receptors. These hormone sensitive cells localize to ducts and seem not to be targeted by TAg. Despite reaching an advanced stage in alveolar differentiation, the cells in hyperplasia do not exit the cell cycle. Thus, expression of TAg in conjunction with regular morphogenetic processes of alveologenesis seem to provide the basis for a hormone independent, unscheduled proliferation of differentiating cells in resting glands of WAP-T1 transgenic mice, leading to the formation of hyperplastic lesions.

Adverse Histopathology and Imaging Findings in Reduction Mammaplasty Day-surgery Patients

Background and Aims:

Reduction mammaplasty is a popular procedure in plastic surgery. Occasionally, occult invasive breast carcinoma or findings demonstrating increased risk of breast cancer occur in reduction mammaplasty specimens. The incidences have been studied elsewhere, but in Finland, the data on this subject are lacking. Our aim was to analyze the incidence of occult invasive and in situ carcinoma and benign breast disease causing increased risk of breast cancer in reduction mammaplasty specimens. We also analyzed preoperative mammograms and ultrasound images and compared findings with reduction mammaplasty specimens.

Material and Methods:

We performed a retrospective study of 100 women who underwent reduction mammaplasty during 1 January 2007 to 30 April 2009 in Jorvi Hospital day-surgery unit. Demographic data, findings in preoperative imaging, pathology reports, postoperative follow-up, and retrospective reanalysis of preoperative imaging were recorded.

Results:

Histological abnormality occurred in 14.6% of the patients. In situ carcinoma was diagnosed in 4.5% of the patients, and findings demonstrating increased risk of breast cancer were diagnosed in 13.5% of the patients. More than one lesion demonstrating increased risk of breast cancer was diagnosed in 4.5% of the patients. No invasive carcinoma occurred. Preoperative mammogram was performed for the majority (94.0%) of the patients.

Conclusions:

We detected a considerable amount of findings in reduction mammaplasty specimens with prognostic value with regard to future breast cancer risk. We recommend histological analysis for reduction mammaplasty specimens and focus attention on systematically performed preoperative imaging.

[Diagnostics of benign ductal epithelial cell proliferation of the breast in biopsy material]

The pathological evaluation of radiological or sonographical abnormalities by needle core biopsy of the breast frequently involves the differential diagnosis of benign epithelial cell proliferations. The lesions to be considered include usual type and atypical ductal epithelial cell hyperplasia, columnar cell changes including flat epithelial cell atypia, the spectrum of hyperplastic and atypical apocrine epithelial cell proliferations and papillary lesions. This review provides an overview of the diagnostic criteria, the current terminology and the differential diagnosis of these lesions. The clinical management and the prognosis of the lesions are discussed.

Women with familial risk for breast cancer have an increased frequency of aldehyde dehydrogenase expressing cells in breast ductules

Background

Knowledge is limited regarding the association between stem cells in histologically benign breast tissue and risk factors for breast cancer, and hence we addressed this issue in the present study. Recently, we assessed the histology of benign breast tissue from cancer and non-cancer patients for cells positive for the putative stem cell marker aldehyde dehydrogenase 1 A1 (ALDH), and the findings indicated an association between expression of ALDH and the hormonal factors menopause and hormone therapy. The current investigation examined possible associations between various known clinical and genetic risk factors for breast cancer and cellular expression of ALDH in ductules in benign human breast tissue.

Methods

The study included breast surgery patients that were BRCA1/2 mutation carriers without breast cancer (n = 23), had BRCA1/2 (n = 28) or sporadic (n = 21) breast cancer, or required non-cancer-related mammoplasty (n = 34). The distribution and frequency of ALDH-immunolabelled cells were correlated to patient subgroups with different risk factors, using mammoplasty patients as a control group. Statistical analyses comprised linear and logistic regression, Spearman’s rank test, Pearson’s test, and Fisher’s exact test. In two-tailed tests, p < 0.05 was considered significant.

Results

A strong association was found between family history of breast cancer and a high frequency of ALDH+ cells (p = 0.001) at all ductular levels in all groups, regardless of BRCA status, age, parity, or occurrence of cancer. In pre-menopausal non-BRCA cancer patients, the frequency of ALDH+ cells increased with age (p < 0.01) but decreased with increasing parity (p < 0.03). High frequencies of ALDH+ cells were found in the non-basal ductular levels in BRCA1 mutation carriers (p = 0.03), but in the basal ductular level in BRCA2 cancer patients (p = 0.02). Among post-menopausal patients, only on-going hormone replacement therapy was correlated with a high number of ALDH+ cells (p < 0.03).

Conclusion

In histologically normal breast tissue, we found a positive association between the frequency of ductular ALDH+ cells and several breast cancer risk factors, particularly family history of this disease, which supports previous evidence that ALDH plays a role in breast cancer.