In vivo MRI of early stage mammary cancers and the normal mouse mammary gland

Since the advent of screening mammography, approximately one-quarter of newly diagnosed breast cancers are at the earliest preinvasive stage of ductal carcinoma in situ (DCIS). Concomitant with this improvement in early detection has been a growing clinical concern that distinguishing aggressive from indolent DCIS is necessary to optimize patient management. Genetically engineered mouse models offer an appealing experimental framework in which to investigate factors that influence and predict progression of preinvasive neoplasias. Because of the small size of early stage carcinomas in mice, high-resolution imaging techniques are required to effectively observe longitudinal progression. The purpose of the present study was to evaluate the feasibility of MRI for assessment of in situ mammary neoplasias and early invasive mammary cancers that stochastically arise in mammary glands of C3(1) SV40 Tag transgenic mice. Additionally, images of normal mammary glands from wild-type FVB/N mice were acquired and compared with those from transgenic mice. Sixteen mice underwent MR examinations employing axial two-dimensional multi-slice gradient recalled echo scans (TR/TE =～1000/5.5 ms) with fat suppression in a two-step process targeting both the upper and lower mammary glands. MRI successfully detected in situ and early invasive neoplasias in transgenic mice with high sensitivity and specificity. The average signal-to-noise ratio (SNR) of in situ lesions on fat-suppressed high-resolution T(1) -weighted images was 22.9, which was lower than that of invasive tumors, lymph nodes and muscle (average SNR of 29.5-34.9, p < 0.0001) but significantly higher than that of normal mammary tissue (average SNR = 5.5, p < 0.0001). Evaluation of wild-type mammary glands revealed no cancerous or benign lesions, and comparable image contrast characteristics (average SNR = 5.2) as compared with normal tissue areas of transgenic mice. This present study demonstrates that MRI is an excellent candidate for performing longitudinal assessment of early stage mammary cancer disease progression and response to therapy in the transgenic model system.     

A critical appraisal of six modern classifications of ductal carcinoma in situ of the breast (DCIS): correlation with grade of associated invasive carcinoma

The in-situ component of 180 cases of screen detected infiltrating duct carcinoma of the breast was classified according to six published classifications for ductal carcinoma in situ based on architecture, necrosis and cytology. All cases were assessed independently by two experienced observers to assess inter-observer variation. The differentiation of ductal carcinoma in situ as assessed by all the classification systems correlated with the grade of the associated invasive carcinoma (chi-squared between 50 and 107: P <0.0001). Disagreements were commonest in the assessment of architecture and least common in the assessment of necrosis. For cytonuclear grade most disagreements (62.2%) involved the distinction between low and intermediate as against 33.9% disagreements for intermediate vs. high. Nuclear grade alone and necrosis alone were correlated with the grade of invasive carcinoma associated with the ductal carcinoma in situ and the Nottingham prognostic index of the patient. The Van Nuys classification of ductal carcinoma in situ is commended because it has a low inter-observer disagreement, is significantly correlated with the grade of the infiltrating carcinoma, uses simple well-defined criteria (with no requirement for percentage estimations), is applicable to small numbers of ducts and, most importantly, appears to correlate with disease-free survival.     

MRI reveals increased tumorigenesis following high fat feeding in a mouse model of triple‐negative breast cancer

High animal fat consumption is associated with an increase in triple‐negative breast cancer (TNBC) risk. Based on previous MRI studies demonstrating the feasibility of detecting very early non‐palpable mammary cancers in simian virus 40 large T antigen (SV40TAg) mice, we examined the effect of dietary fat fed from weaning to young adulthood in this model of TNBC. Virgin female C3(1)SV40TAg mice (n = 16) were weaned at 3–4 weeks of age and then fed either a low fat diet (LFD) (n = 8, 3.7 kcal/g; 17.2% kcal from vegetable oil) or a high animal fat diet (HAFD) (n = 8, 5.3 kcal/g; 60% kcal from lard). After 8 weeks on the diet (12 weeks of age), fast spin echo MR images of inguinal mammary glands were acquired at 9.4 T. Following in vivo MRI, mice were sacrificed and inguinal mammary glands were excised and formalin fixed for ex vivo MRI. 3D volume‐rendered MR images were then correlated with mammary gland histology to assess the glandular parenchyma and tumor burden. Using in vivo MRI, an average of 3.88 ± 1.03 tumors were detected per HAFD‐fed mouse compared with an average of 1.25 ± 1.16 per LFD‐fed mouse (p < 0.007). Additionally, the average tumor volume was significantly higher following HAFD feeding (0.53 ± 0.45 mm³) compared with LFD feeding (0.20 ± 0.08 mm³, p < 0.02). Analysis of ex vivo MR and histology images demonstrated that HAFD mouse mammary glands had denser parenchyma, irregular and enlarged ducts, dilated blood vessels, increased white adipose tissue, and increased tumor invasion. MRI and histological studies of the SV40TAg mice demonstrated that HAFD feeding also resulted in higher cancer incidence and larger mammary tumors. Unlike other imaging methods for assessing environmental effects on mammary cancer growth, MRI allows routine serial measurements and reliable detection of small cancers as well as accurate tumor volume measurements and assessment of the three‐dimensional distribution of tumors over time.     

Dynamic contrast-enhanced MRI in the diagnosis and management of breast cancer

Dynamic contrast-enhanced MRI (DCE-MRI) is an evolving tool for determining breast disease, which benefits from the move to imaging at 3 T. It has major capabilities for the diagnosis, detection and monitoring of malignancy. It benefits from being non-invasive and three-dimensional, allowing visualisation of the extent of disease and its angiogenic properties, visualisation of lesion heterogeneity, detection of changes in angiogenic properties before morphological alterations, and the potential to predict the overall response either before the start of therapy or early during treatment. In addition, DCE-MRI is emerging as a powerful tool for screening high-risk patients and for detecting high-grade ductal carcinoma in situ. However, there are also a number of limitations, including the overlap in enhancement patterns between malignant and benign disease, the failure to resolve microscopic disease particularly in the neoadjuvant setting, and the inconsistent predictive value of the enhancement pattern for clinical outcome. Careful consideration should be given to the technical requirements of individual examinations and the need for automation of post-processing techniques to appropriately handle the growing volume of data acquired. Research continues, focusing on the use of higher field strengths with improved spatial and temporal resolution data, improving understanding of the mechanism of contrast enhancement at the cellular level, and developing macromolecular and targeted contrast agents.     

Evaluation of CD56 and CD57 immunostainings for discrimination between endocrine ductal carcinoma in situ and intraductal papilloma

Endocrine ductal carcinoma in situ (E‐DCIS) is an intraductal carcinoma characterized by endocrine features and expression of neuroendocrine markers. E‐DCIS and intraductal papilloma (IDP) resemble in their clinical features. However, the former is an intraductal carcinoma, and the latter is an intraductal benign lesion. It is sometimes difficult to distinguish E‐DCIS from IDP because both can show near solid intraductal cellular proliferation. Discrimination between lesions is important not only histopathologically, but also clinically. This study aimed to evaluate the applicability of CD56 and CD57 for the discrimination between E‐DCIS and IDP. Specimens were obtained from 17 E‐DCIS patients as the subject group, and 27 IDP patients as the control group, diagnosed in St Marianna University Hospital. E‐DCIS was diagnosed using Chromogranin A, Synaptophysin, and Grimelius stainings by the premise of histopathological features. These specimens were subjected to CD56, CD57 immunostainings. Staining results were compared between E‐DCIS and IDP. In our study, CD56 revealed significant differences for distinguishing E‐DCIS from IDP as determined by Fisher's test (cutoff: not less than 33–67%< immunopositivity, P < 0.05). We found that not only E‐DCIS but also IDP revealed immunopositivity for CD56. However, it is considered that E‐DCIS diagnosis is possible by diffuse immunopositivity of CD56 after having been based on histopathology.     

The impact of large sections on the study of in situ and invasive duct carcinoma of the breast

Large histologic sections (LHSs) are increasingly used in the study of normal and neoplastic breast tissue. LHSs allow the direct visualization of a large part of the breast glandular tree. Accordingly, LHSs have shown that in situ and invasive lobular carcinoma is a multilobar (and hence multifocal) neoplastic lesion in more than 50% of the cases, and that poorly differentiated duct carcinoma in situ (DCIS grade 3) is frequently unifocal, whereas it is often multifocal when the in situ lesion is a well-differentiated type (DCIS grade 1). Forty-five mastectomies were studied with large sections. Mastectomies were performed when quadrantectomy did not guarantee radical excision of the tumor with adequate cosmesis because of the large size of the lesion or because the neoplastic lesion was located below the nipple. Excluded were cases of lobular neoplasia or invasive lobular carcinoma, because they were reported separately, and cases of mastectomies performed for sarcoma or recurrent phyllodes tumor. All cases had undergone a preoperative diagnostic procedure (fine needle aspiration), and the relative positive material was reviewed. All 45 cases showed in situ duct carcinoma and 37 showed evidence of invasive duct carcinoma. Forty-two cases of DCIS were multifocal, whereas only 4 invasive duct carcinoma were shown as multifocal. When DCIS lesions were subdivided into 3 grades, no statistical significance was seen among the 3 groups of DCIS in regard to multifocality. Nevertheless, DCIS grade 1 was a widespread condition involving more than one lobe and quadrant, whereas DCIS grades 2 and 3 appeared more localized. DCIS grade 1 was more similar to that previously observed in lobular in situ neoplasia/lobular in situ carcinoma. In 66.6% of the cases, DCIS foci were found within the invasive areas, indicating a more than fortuitous occurrence (2-sided P=.0357).     

Expression and mutational status of RON in neoplastic lesions of the breast: analysis of MSP/RON signaling in ductal carcinoma in situ and invasive ductal carcinoma

Recepteur d'origine nantais (RON) is a receptor tyrosine kinase closely related to MET and involved in tumorigenesis. We investigated the roles of aberrations in RON and its ligand, macrophage-stimulating protein (MSP), in invasive ductal carcinoma (IDC, n = 81), ductal carcinoma in situ (DCIS, n = 26), and in benign lesions (n = 20) of mammary gland. Expression of RON and MSP was evaluated by immunohistochemistry and the mutational status of a region containing the proteolytic cleavage site in exon 1 and each exon of the kinase domain (exon 14-20) of RON was screened by polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) analysis. The proportion of cases positive for RON expression was significantly different between malignant [86% (92/107)] and benign [40% (8/20)] lesions. RON expression was positive in both IDC and DCIS [90% (73/81) and 73% (19/26), respectively], whereas MSP expression was present in 54% (44/81) of IDC and absent in DCIS. RON expression correlated significantly with the histological grade of DCIS. No mutations were detected in the examined regions of RON in breast cancer samples as confirmed by PCR-SSCP. The findings suggest the involvement of RON expression in the development of breast cancer, and that an autocrine/paracrine loop of RON seems to affect tumor invasiveness.     

Magnetic resonance angiography reveals increased arterial blood supply and tumorigenesis following high fat feeding in a mouse model of triple‐negative breast cancer

Breast cancer is the second most commonly diagnosed malignancy among women globally. Past MRI studies have linked a high animal fat diet (HAFD) to increased mammary cancer risk in the SV40Tag mouse model of triple‐negative breast cancer. Here, serial MRI examines tumor progression and measures the arterial blood volume feeding mammary glands in low fat diet (LFD) or HAFD fed mice. Virgin female C3(1)SV40Tag mice (n = 8), weaned at 3 weeks old, were assigned to an LFD (n = 4, 3.7 kcal/g, 17.2% kcal from vegetable oil) or an HAFD (n = 4, 5.3 kcal/g, 60% kcal from lard) group. From ages 8 to 12 weeks, weekly fast spin echo MR images and time‐of‐flight (TOF) MR angiography of inguinal mammary glands were acquired at 9.4 T. Following in vivo MRI, mice were sacrificed. Inguinal mammary glands were excised and fixed for ex vivo MRI and histology. Tumor, blood, and mammary gland volumes for each time point were measured from manually traced regions of interest; tumors were classified as invasive by histopathology‐blinded observers. Our analysis confirmed a strong correlation between total tumor volume and blood volume in the mammary gland. Tumor growth rates from weeks 8‐12 were twice as high in HAFD‐fed mice (0.42 ± 0.14/week) as in LFD‐fed mice (0.21 ± 0.03/week), p < 0.004. Mammary gland blood volume growth rate was 2.2 times higher in HAFD mice (0.29 ± 0.11/week) compared with LFD mice (0.13 ± 0.06/week), p < 0.02. The mammary gland growth rate of HAFD‐fed mice (0.071 ± 0.011/week) was 2.7 times larger than that of LFD‐fed mice (0.026 ± 0.009/week), p < 0.01. This is the first non‐invasive, in vivo MRI study to demonstrate a strong correlation between an HAFD and increased cancer burden and blood volume in mammary cancer without using contrast agents, strengthening the evidence supporting the adverse effects of an HAFD on mammary cancer. These results support the potential future use of TOF angiography to evaluate vasculature of suspicious lesions.     

Warty/basaloid penile intraepithelial neoplasia is more prevalent than differentiated penile intraepithelial neoplasia in nonendemic regions for penile cancer when compared with endemic areas: a comparative study between pathologic series from Paris and Paraguay

Penile squamous cell carcinoma shows an ample geographic variation in its prevalence with regions of low (North America, Europe, Japan, and Israel) and high (Africa, Asia, and South America) incidence. However, the geographic variation in the distribution of penile intraepithelial neoplasia is not well established. The aim of the present study was to compare the distribution of in situ and invasive lesions between geographic areas with low (France) and high (Paraguay) penile cancer incidence using a series of consecutive cases. The French series included 86 cases (57 in situ and 29 in situ + invasive squamous cell carcinoma), and the Paraguayan series, 117 cases (31 in situ and 86 in situ + invasive squamous cell carcinoma). Incidence of invasive squamous cell carcinoma in the overall samples was higher in the Paraguayan series (P < .00001). Comparing the Paraguayan and the French series, differentiated penile intraepithelial neoplasia was more prevalent in the former (65.0% versus 19.8%), whereas lesions showing warty and/or basaloid features predominated in the latter (35.0% versus 80.2%) to a significant level (P < .00001). This distinctive pattern of differential distribution was maintained when cases with associated invasive squamous cell carcinoma were excluded. The pattern of distribution of lichen sclerosus was also distinctive, with a significantly higher prevalence in the Paraguayan population when compared with the French series (32.5% versus 12.8%, P = .0015). In summary, there appears to be a distinctive distribution of penile precursor lesions depending on the geographic region in consideration. Penile intraepithelial neoplasia with warty and/or basaloid features predominated in low-incidence areas, whereas differentiated penile intraepithelial neoplasia was more prevalent in endemic regions for penile cancer. Further prospective studies in matched populations and from different geographic regions are needed to further clarify the reasons for this discrepancy.     

Fluorescence in situ hybridization analysis with a tissue microarray: ‘FISH and chips’ analysis of pathology archives

Practicing pathologists expect major somatic genetic changes in cancers, because the morphological deviations in the cancers they diagnose are so great that the somatic genetic changes to direct these phenotypes of tumors are supposed to be correspondingly tremendous. Several lines of evidence, especially lines generated by high‐throughput genomic sequencing and genome‐wide analyses of cancer DNAs are verifying their preoccupations. This article reviews a comprehensive morphological approach to pathology archives that consists of fluorescence in situ hybridization with bacterial artificial chromosome (BAC) probes and screening with tissue microarrays to detect structural changes in chromosomes (copy number alterations and rearrangements) in specimens of human solid tumors. The potential of this approach in the attempt to provide individually tailored medical practice, especially in terms of cancer therapy, is discussed.