Rachel E. Factor

Tumor grafts derived from women with breast cancer authentically reflect tumor pathology, growth, metastasis and disease outcomes

Development and preclinical testing of new cancer therapies is limited by the scarcity of in vivo models that authentically reproduce tumor growth and metastatic progression. We report new models for breast tumor growth and metastasis in the form of transplantable tumors derived directly from individuals undergoing treatment for breast cancer. These tumor grafts illustrate the diversity of human breast cancer and maintain essential features of the original tumors, including metastasis to specific sites. Co-engraftment of primary human mesenchymal stem cells maintains phenotypic stability of the grafts and increases tumor growth by promoting angiogenesis. We also report that tumor engraftment is a prognostic indicator of disease outcome for women with newly diagnosed breast cancer; orthotopic breast tumor grafting is a step toward individualized models for tumor growth, metastasis and prognosis. This bank of tumor grafts also serves as a publicly available resource for new models in which to study the biology of breast cancer.

The nuclear envelope environment and its cancer connections

Because of the association between aberrant nuclear structure and tumour grade, nuclear morphology is an indispensible criterion in the current pathological assessment of cancer. Components of the nuclear envelope environment have central roles in many aspects of cell function that affect tumour development and progression. As the roles of the nuclear envelope components, including nuclear pore complexes and nuclear lamina, are being deciphered in molecular detail there are opportunities to harness this knowledge for cancer therapeutics and biomarker development. In this Review, we summarize the progress that has been made in our understanding of the nuclear envelope and the implications of changes in this environment for cancer biology.

Protein Arginine Methyltransferase 5 Accelerates Tumor Growth by Arginine Methylation of the Tumor Suppressor Programmed Cell Death 4

Programmed cell death 4 (PDCD4) has been described as a tumor suppressor, with high expression correlating with better outcomes in a number of cancer types. Yet a substantial number of cancer patients with high PDCD4 in tumors have poor survival, suggesting that oncogenic pathways may inhibit or change PDCD4 function. Here, we explore the significance of PDCD4 in breast cancer and identify protein arginine methyltransferase 5 (PRMT5) as a cofactor that radically alters PDCD4 function. Specifically, we find that coexpression of PDCD4 and PRMT5 in an orthotopic model of breast cancer causes accelerated tumor growth and that this growth phenotype is dependent on both the catalytic activity of PRMT5 and a site of methylation within the N-terminal region of PDCD4. In agreement with the xenograft model, elevated PDCD4 expression was found to correlate with worse outcome within the cohort of breast cancer patients whose tumors contain higher levels of PRMT5. These results reveal a new cofactor for PDCD4 that alters its tumor suppressor functions and point to the utility of PDCD4/PRMT5 status as both a prognostic biomarker and a potential target for chemotherapy.

Intrinsic Subtypes from PAM50 Gene Expression Assay in a Population-Based Breast Cancer Cohort: Differences by Age, Race, and Tumor Characteristics

Background: Data are lacking to describe gene expression–based breast cancer intrinsic subtype patterns for population-based patient groups. Methods: We studied a diverse cohort of women with breast cancer from the Life After Cancer Epidemiology and Pathways studies. RNA was extracted from 1 mm punches from fixed tumor tissue. Quantitative reverse-transcriptase PCR was conducted for the 50 genes that comprise the PAM50 intrinsic subtype classifier. Results: In a subcohort of 1,319 women, the overall subtype distribution based on PAM50 was 53.1% luminal A, 20.5% luminal B, 13.0% HER2-enriched, 9.8% basal-like, and 3.6% normal-like. Among low-risk endocrine-positive tumors (i.e., estrogen and progesterone receptor positive by immunohistochemistry, HER2 negative, and low histologic grade), only 76.5% were categorized as luminal A by PAM50. Continuous-scale luminal A, luminal B, HER2-enriched, and normal-like scores from PAM50 were mutually positively correlated. Basal-like score was inversely correlated with other subtypes. The proportion with non-luminal A subtype decreased with older age at diagnosis, PTrend < 0.0001. Compared with non-Hispanic Whites, African American women were more likely to have basal-like tumors, age-adjusted OR = 4.4 [95% confidence intervals (CI), 2.3–8.4], whereas Asian and Pacific Islander women had reduced odds of basal-like subtype, OR = 0.5 (95% CI, 0.3–0.9). Conclusions: Our data indicate that over 50% of breast cancers treated in the community have luminal A subtype. Gene expression–based classification shifted some tumors categorized as low risk by surrogate clinicopathologic criteria to higher-risk subtypes. Impact: Subtyping in a population-based cohort revealed distinct profiles by age and race. Cancer Epidemiol Biomarkers Prev; 23(5); 714–24. ©2014 AACR.

High-frequency ultrasound for intraoperative margin assessments in breast conservation surgery: a feasibility study

BackgroundIn addition to breast imaging, ultrasound offers the potential for characterizing and distinguishing between benign and malignant breast tissues due to their different microstructures and material properties. The aim of this study was to determine if high-frequency ultrasound (20-80 MHz) can provide pathology sensitive measurements for the ex vivo detection of cancer in margins during breast conservation surgery.MethodsUltrasonic tests were performed on resected margins and other tissues obtained from 17 patients, resulting in 34 specimens that were classified into 15 pathology categories. Pulse-echo and through-transmission measurements were acquired from a total of 57 sites on the specimens using two single-element 50-MHz transducers. Ultrasonic attenuation and sound speed were obtained from time-domain waveforms. The waveforms were further processed with fast Fourier transforms to provide ultrasonic spectra and cepstra. The ultrasonic measurements and pathology types were analyzed for correlations. The specimens were additionally re-classified into five pathology types to determine specificity and sensitivity values.ResultsThe density of peaks in the ultrasonic spectra, a measure of spectral structure, showed significantly higher values for carcinomas and precancerous pathologies such as atypical ductal hyperplasia than for normal tissue. The slopes of the cepstra for non-malignant pathologies displayed significantly greater values that differentiated them from the normal and malignant tissues. The attenuation coefficients were sensitive to fat necrosis, fibroadenoma, and invasive lobular carcinoma. Specificities and sensitivities for differentiating pathologies from normal tissue were 100% and 86% for lobular carcinomas, 100% and 74% for ductal carcinomas, 80% and 82% for benign pathologies, and 80% and 100% for fat necrosis and adenomas. Specificities and sensitivities were also determined for differentiating each pathology type from the other four using a multivariate analysis. The results yielded specificities and sensitivities of 85% and 86% for lobular carcinomas, 85% and 74% for ductal carcinomas, 100% and 61% for benign pathologies, 84% and 100% for fat necrosis and adenomas, and 98% and 80% for normal tissue.ConclusionsResults from high-frequency ultrasonic measurements of human breast tissue specimens indicate that characteristics in the ultrasonic attenuation, spectra, and cepstra can be used to differentiate between normal, benign, and malignant breast pathologies.

Understanding Sources of Bias in Diagnostic Accuracy Studies

CONTEXT Accuracy is an important feature of any diagnostic test. There has been an increasing awareness of deficiencies in study design that can create bias in estimates of test accuracy. Many pathologists are unaware of these sources of bias. OBJECTIVE To explain the causes and increase awareness of several common types of bias that result from deficiencies in the design of diagnostic accuracy studies. DATA SOURCES We cite examples from the literature and provide calculations to illustrate the impact of study design features on estimates of diagnostic accuracy. In a companion article by Schmidt et al in this issue, we use these principles to evaluate diagnostic studies associated with a specific diagnostic test for risk of bias and reporting quality. CONCLUSIONS There are several sources of bias that are unique to diagnostic accuracy studies. Because pathologists are both consumers and producers of such studies, it is important that they be aware of the risk of bias.

Intrinsic subtypes from the PAM50 gene expression assay in a population-based breast cancer survivor cohort: Prognostication of short and long term outcomes.

Background: The PAM50, a gene expression assay to categorize breast tumors into intrinsic subtypes, has not been previously used to examine short- and long-term prognostication in a population-based cohort where treatment patterns and time of initial follow-up vary. Methods: In a stratified case–cohort design of 1,691 women from the LACE and Pathways breast cancer survivor cohorts, we used PAM50 to categorize tumors into Luminal A (LumA), Luminal B (LumB), HER2-enriched (HER2-E), Basal-like and Normal-like, and to examine risk of early and late recurrence and mortality by Cox proportional hazards regression. Results: Compared with LumA, cumulative risk of recurrence and breast cancer death was higher for LumB, HER2-E, and Basal-like tumors at 2, 5, and 10 years. However, HR of breast cancer death varied over time [<5 years (early) vs. > 5 years (late)] for both Basal-like (HR, 6.23 early vs. HR, 0.63 late) and HER2-E tumors (HR, 2.97 early vs. HR, 0.73 late) but not for LumB tumors where risk was elevated consistently (HR, 2.67 early vs. HR, 1.47 late). The contrast between LumB, HER2-E, and Basal-like compared with LumA on early recurrence was stronger when subtype was defined by PAM50 than by immunohistochemistry (IHC) markers. Conclusions: The PAM50 categorized intrinsic subtypes in a manner that more accurately predicts recurrence and survival, especially for luminal tumors, compared with commonly used methods that rely on traditional IHC clinical markers. Impact: The PAM50 is robust for use in epidemiologic studies and should be considered when archived tumor tissues are available. Cancer Epidemiol Biomarkers Prev; 23(5); 725–34. ©2014 AACR.

Pulmonary pathology in pediatric cerebral malaria

Respiratory signs are common in African children where malaria is highly endemic, and thus, parsing the role of pulmonary pathology in illness is challenging. We examined the lungs of 100 children from an autopsy series in Blantyre, Malawi, many of whom death was attributed to Plasmodium falciparum malaria. Our aim was to describe the pathologic manifestations of fatal malaria; to understand the role of parasites, pigment, and macrophages; and to catalog comorbidities. From available patients, which included 55 patients with cerebral malaria and 45 controls, we obtained 4 cores of lung tissue for immunohistochemistry and morphological evaluation. We found that, in patients with cerebral malaria, large numbers of malaria parasites were present in pulmonary alveolar capillaries, together with extensive deposits of malaria pigment (hemozoin). The number of pulmonary macrophages in this vascular bed did not differ between patients with cerebral malaria, noncerebral malaria, and nonmalarial diagnoses. Comorbidities found in some cerebral malaria patients included pneumonia, pulmonary edema, hemorrhage, and systemic activation of coagulation. We conclude that the respiratory distress seen in patients with cerebral malaria does not appear to be anatomic in origin but that increasing malaria pigment is strongly associated with cerebral malaria at autopsy.

Diagnostic Efficacy and Safety of Computed Tomography-Guided Transthoracic Needle Biopsy in Patients with Hematologic Malignancies

RATIONALE AND OBJECTIVES The role of transthoracic needle biopsy (TTNB) in patients with hematologic malignancies, particularly in discriminating between malignant and benign etiologies, has not been well studied. Hence, the diagnostic efficacy and safety of computed tomography-guided TTNB were retrospectively evaluated in this population. MATERIALS AND METHODS The records of 53 patients with hematologic malignancies who underwent TTNB from August 1, 1999, to July 31, 2007, were reviewed. Potential factors for increased diagnostic yield and risk for complications were collected and analyzed, including the status of neutropenia, thrombocytopenia, chemotherapy, and transplant as well as lesion size and location. Both cytopathologic and microbiologic results were assessed. RESULTS The most common underlying hematologic malignancy was non-Hodgkin lymphoma, in 20 patients (37.7%). Lesions were most frequently located in the left upper lobe (16 [30.2%]); 33 lesions were pleural based (63.5%), and nine had cavitation (17.0%). TTNB established specific diagnoses in 22 patients (41.5%): malignancies was found in 12 (22.6%) and infections in 10 (18.9%). Sensitivity for detecting malignancy was 50.0%, and sensitivity for the detection of a specific infection was 40.0%. There were no false-positive results. Complications occurred in nine patients (17.0%): self-limited small-volume hemoptysis in one patient (1.9%) and pneumothorax in eight patients (15.1%), one requiring chest tube placement. The results of TTNB led to changes in antimicrobial therapy for eight of the 22 patients with specific diagnoses (36.4%). CONCLUSIONS TTNB is a safe diagnostic procedure in patients with hematologic malignancies and has the potential of making specific diagnoses with minimal morbidity.

Cytogenetics and fluorescence in situ hybridization as adjuncts to cytology in the diagnosis of malignant mesothelioma

Virtually all malignant mesotheliomas (MMs) exhibit clonal chromosomal aberrations. Although the chromosome regions affected by these aberration(s) may vary from 1 tumor to another, certain regions are commonly disrupted. These aberrations are absent in benign mesothelial cells, and therefore their presence can be used to confirm a diagnosis of MM. In the current study, the authors investigated the value of karyotyping and fluorescence in situ hybridization (FISH) as adjuncts to conventional cytologic examination in patients with MM.