CAP TODAY Pathology/Laboratory Medicine/Laboratory Management
Editors: Rouzan Karabakhtsian, MD, PhD, associate professor of pathology, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY, and Rachel Stewart, DO, PhD, molecular genetic pathology fellow, University of Utah/ARUP Laboratories, Salt Lake City.
MCM2: an alternative to Ki-67 for measuring breast cancer cell proliferatio
Role of ovarian stroma in epithelial ovarian tumor response to steroid hormone stimulation
P-cadherin: a useful biomarker for axillary-based breast cancer decisions
Clinicopathological and molecular characterization of SMARCA4-deficient thoracic sarcomas
MCM2: an alternative to Ki-67 for measuring breast cancer cell proliferatio
Breast cancer is a heterogeneous disease comprised of a diversity of tumor subtypes that manifest themselves in a wide variety of clinical, pathological, and molecular features. One important subset, luminal breast cancer, comprises two clinically distinct subtypes—luminal A and B—each of which is endowed with its own genetic program of differentiation and proliferation. Luminal breast cancers were operationally defined as luminal A: ER+, PR+, HER2−, and Ki-67 less than 14 percent; and luminal B: ER+ and/or PR+, HER2−, Ki-67 of 14 percent or more, or, alternatively, ER+ and/or PR+, HER2+, and any Ki-67. A clinically robust and validated immunohistochemical assay that can help distinguish between luminal A and B breast cancer is needed. MCM2 is a family member of the minichromosome maintenance protein complex whose role in DNA replication and cell proliferation is firmly established. Because MCM2 appears to be an attractive alternative to Ki-67, the authors studied the expression of MCM2 and Ki-67 in different histological grades and molecular subtypes of breast cancer, focusing primarily on ER-positive tumors. They analyzed MCM2 and Ki-67 mRNA expression using in silico analysis of available DNA microarray and RNA-sequencing data of human breast cancer. The authors then used immunohistochemistry to evaluate protein expression of MCM2 and Ki-67 on tissue microarrays of invasive breast carcinoma. They found that MCM2 and Ki-67 are highly expressed in breast tumors of high histological grades, comprising clinically aggressive tumors such as triple-negative, HER2-positive, and luminal B subtypes. MCM2 expression was detected at higher levels than Ki-67 in normal breast tissues and breast cancers. The bimodal distribution of MCM2 scores in ER+/HER2− breast tumors led to the identification of two distinct subgroups with different relapse-free survival rates. The authors concluded that MCM2 expression can help sort out two clinically important subsets of luminal breast cancer whose treatment and clinical outcomes are likely to diverge.
Yousef EM, Furrer D, Laperriere DL, et al. MCM2: An alternative to Ki-67 for measuring breast cancer cell proliferation. Mod Pathol. 2017;30:682–697.
Correspondence: Dr. L. Gaboury at louis.gaboury@umontreal.ca
Expression of PD-L1 and presence of CD8+ T cells in pretreatment specimens of locally advanced cervical cancer
Several of the cancer immunotherapies under investigation or in clinical use target the programmed death-ligand 1/programmed death-1 (PD-L1/PD-1) signaling axis. PD-L1 expression in tumor samples has been used as a predictive marker for response to these therapeutics and may also have independent prognostic utility when assessed with immune cell markers. The authors conducted a study to assess the expression of PD-L1 in tumor specimens from a uniformly treated patient cohort with locally advanced cervical cancer and determine its prognostic significance along with the density of tumor-infiltrating T cells. They identified 120 patients with locally advanced cervical cancer treated with radical chemoradiotherapy and built tissue microarrays from their formalin-fixed, paraffin-embedded pretreatment biopsies. They used conventional brightfield and fluorescence immunohistochemistry to detect PD-L1 and quantified protein expression using manual pathologist scoring and automated software analysis. They also evaluated the effect of PD-L1 expression in tumors, along with the presence and density of intra-tumoral CD8+ T cells, on patient survival outcomes. Approximately 96 percent of the tumor samples expressed PD-L1, as determined using quantitative software analysis. Neither expression of PD-L1 nor density of CD8+ T cells was associated with progression-free or overall survival. However, a trend toward worse progression-free survival was noted for patients whose tumors expressed PD-L1 but lacked CD8+ T cells (hazard ratio, 0.43 [0.18–1.01]; P = .053). Nevertheless, the high percentage of cervical cancer tumor samples expressing PD-L1 suggests that anti-PD-L1 or anti-PD-1 therapies are potential treatment options for this patient population.
Enwere EK, Kornaga EN, Dean M, et al. Expression of PD-L1 and presence of CD8-positive T cells in pre-treatment specimens of locally advanced cervical cancer. Mod Pathol. 2017;30:577–586.
Correspondence: Dr. C. M. Doll at corinne.doll@ahs.ca
Role of ovarian stroma in epithelial ovarian tumor response to steroid hormone stimulation
The ovarian stroma may play a direct role in the responsiveness of epithelial ovarian tumors to steroid hormone stimulation. The authors conducted a study of this potential connection by evaluating immunohistochemical markers of sex-steroid differentiation and steroidogenesis (calretinin, inhibin, and steroidogenic factor 1), steroid enzymes involved in hormone biosynthesis (CYP17, CYP19, HSD17β1, and AKR1C3), and hormone receptors (estrogen receptor, progesterone receptor, and androgen receptor) in 101 epithelial ovarian tumors and normal structures implicated in ovarian carcinogenesis (ovarian surface epithelium and cortical inclusion cysts). They hypothesized that the ovarian stroma immediately adjacent to tumors expresses markers of sex-steroid differentiation and steroidogenesis and steroid enzymes, whereas the epithelium contains corresponding hormone receptors. Because the findings in seromucinous, endometrioid, and clear cell neoplasms (tumors closely associated with endometriosis) were very similar, the entities were combined into a group designated endometriosis-related tumors. Significantly increased expression of markers of sex-steroid differentiation and steroidogenesis was found in the stroma immediately adjacent to endometriosis-related tumors (P = .003) and mucinous tumors (with primary and metastatic mucinous tumors combined because of similar findings; P < .0001) when compared with the more remote ovarian stroma. In addition, sex-steroid enzymes were increased in the stroma adjacent to endometriosis-related tumors (P = .02) and mucinous tumors (P = .02) when compared with the more distant stroma. Steroid hormone receptors showed greater expression in the epithelium when compared with stroma in the endometriosis-related tumors (P = .0009), low-grade serous tumors (P < .0001), and high-grade serous carcinoma (P = .0036). In contrast, greater expression was found in stroma than in the epithelium (P < .0001) in mucinous tumors. The authors concluded that these findings strongly support the view that the stroma surrounding epithelial tumors in the ovary is activated to elaborate steroid hormones, which may stimulate further neoplastic growth. The precise mechanisms by which this process may occur are complex and require further investigation.
Blanco LZ Jr, Kuhn E, Morrison JC, et al. Steroid hormone synthesis by the ovarian stroma surrounding epithelial ovarian tumors: a potential mechanism in ovarian tumorigenesis. Mod Pathol. 2017;30:563–576.
Correspondence: Dr. L. Z. Blanco at luis.blanco@northwestern.edu
P-cadherin: a useful biomarker for axillary-based breast cancer decisions
Axillary lymph node metastases represent the most powerful breast cancer prognostic factor, dictating disease staging and clinical therapeutic decisions. Nonetheless, breast cancer patients with positive lymph nodes still exhibit heterogeneous behavior with regard to disease progression. Stem-like subpopulations of cancer cells show high migratory and metastatic capacity. Therefore, the authors hypothesized that breast cancer stem cell marker evaluation in metastasized lymph nodes could more accurately predict a patient’s prognosis. They evaluated the expression profile of P-cadherin, CD44, and CD49f, which have been associated with stem cell properties in breast cancer, by immunohistochemistry in 135 primary tumors and matched axillary lymph node metastases from 135 breast cancer patients. Taking into consideration the expression of the stem cell markers only in axillary nodes, P-cadherin was the only biomarker significantly associated with poor disease-free and overall patient survival. Moreover, although concordant expression between primary tumors and matched lymph nodes was found in the majority of the cases, a small but significant percentage (18.2–26.2 percent) displayed divergent expression. Remarkably, although CD44 and CD49f changes between primary tumors and lymph node metastases did not impact survival, the cases that were positive for P-cadherin in lymph node metastases being negative in the primary tumor presented the worst disease-free and overall survival rates of the whole series. Accordingly, negative cases for this marker in the lymph nodes with positive expression in the matched breast carcinoma demonstrated a better prognosis, which overlapped with tumors that were negative in both sites. P-cadherin and CD49f gain of expression were mainly found in triple-negative carcinomas. These results indicate that the evaluation of P-cadherin expression in lymph node metastases is an important predictor of disease outcome, serving as a putative valuable marker for axillary-based breast cancer decisions in the clinical practice.
Vieira AF, Dionísio MR, Gomes M, et al. P-cadherin: a useful biomarker for axillary-based breast cancer decisions in the clinical practice. Mod Pathol. 2017;30:698–709.
Correspondence: Dr. J. Paredes at jparedes@ipatimup.pt
Immunohistochemical characterization of origins of metastatic well-differentiated neuroendocrine tumors of the liver
Metastatic neoplasms of unknown primary site pose a major challenge to patient management. Because targeted therapies are being tailored to neuroendocrine tumors (NETs) of different primary sites, identifying the origin of metastatic NETs has become increasingly important. Compared with information on metastatic adenocarcinomas of unknown primary, the literature on metastatic NETs, often of the liver, is relatively sparse, and most studies are based on primary tumors. The authors studied metastatic well-differentiated NETs of the liver to identify markers that predict the site of origin. Eighty-five metastatic NETs of the liver were retrieved from the pathology archive. The primary sites were determined based on pathologic review of the primary tumors, in most cases, but also by radiologic/clinical findings. Immunohistochemical labeling for TTF-1, CDX2, ISL1, NKX2.2, and PDX1 was performed on tissue microarrays or whole sections. The primary sites of the NETs in the study cohort included pancreas (35 percent), small intestine (32 percent), rectum (eight percent), stomach (two percent), bile duct (one percent), lung (nine percent), and unknown primary (12 percent). The authors found predominant expression of TTF-1 in lung carcinoids (63 percent), CDX2 in NETs of the small intestine (89 percent), and ISL1 in pancreatic NETs (77 percent), respectively. NKX2.2 was mainly expressed in NETs of the digestive organs. PDX1 was detected in a small percentage of pancreatic and small intestine NETs and the single bile duct NET. There was no statistically significant association between tumor grade (World Health Organization G1 versus G2) and the expression of any of the above markers. The three-marker panel of TTF-1, CDX2, and ISL1 had sensitivities of 81 percent, 89 percent, and 63 percent; specificities of 100 percent, 94 percent, and 100 percent; positive predictive values of 100 percent, 89 percent, and 100 percent; and negative predictive values of 84 percent, 94 percent, and 96 percent in separating metastatic NETs into the three major primary sites of pancreas/rectum, small intestine, and lung, respectively, with an overall accuracy of 82 percent. Furthermore, this panel predicted a primary site for six of the 10 NETs of unknown primary, which reduced the NETs of unknown primary from 12 percent to five percent. Through immunohistochemical study of a large series of metastatic NETs of the liver, the authors demonstrated the utility of a three-marker panel for identifying one or more potential primary sites of most metastatic NETs, which could help guide patient management.
Yang Z, Klimstra DS, Hruban RH, et al. Immunohistochemical characterization of the origins of metastatic well-differentiated neuroendocrine tumors to the liver. Am J Surg Pathol. 2017;41(7):915–922.
Correspondence: Dr. Laura H. Tang at tangl@mskcc.org
Development of an outcome prediction model for early stage squamous cell carcinoma of the oral cavity
The authors conducted a study to evaluate the histopathologic parameters that predict lymph node metastasis in patients with oral squamous cell carcinoma (OSCC) and to design a new assessment score on the basis of these parameters. The intent of the assessment score, ultimately, is to allow for changes in patient treatment decisions or to aid clinicians in deciding whether there is a need for close follow-up or to perform early lymph node dissection. The authors analyzed the histopathologic parameters of 336 cases of OSCC with stage cT1/T2 N0M0 disease. They recorded the location of the tumor and the type of surgery used to manage the tumor for all patients and examined the parameters, including T stage, grading of tumor, tumor budding, tumor thickness, depth of invasion, shape of tumor nest, lymphoid response at tumor-host interface, pattern of invasion, eosinophilic reaction, foreign-body giant cell reaction, lymphovascular invasion, and perineural invasion. Ninety-two patients had metastasis in lymph nodes. On univariate and multivariate analysis, the independent variables for predicting lymph node metastasis, in descending order, were depth of invasion (P = .003), pattern of invasion (P = .007), perineural invasion (P = .014), grade (P = .028), lymphovascular invasion (P = .038), lymphoid response (P = .037), and tumor budding (P = .039). The authors designed a scoring system on the basis of these statistical results and tested it. Cases with scores ranging from 7 to 11, 12 to 16, and 17 or more points showed lymph node metastasis in 6.4 percent, 22.8 percent, and 77.1 percent of cases, respectively. The difference between these three groups in relation to nodal metastasis was very significant (P < .0001). A patient at low risk for lymph node metastasis (score, 7 to 11) had a five-year survival rate of 93 percent, while moderate-risk patients (score, 12 to 16) had a five-year survival rate of 67 percent, and high-risk patients (score, 17 to 21) had a five-year survival rate of 39 percent. The risk of lymph node metastasis in OSCC is influenced by many histologic parameters that are not routinely analyzed in pathologic reports. These significant independent factors were graded to design a scoring system that permits accurate evaluation of the risk of metastasis with accuracy independent of the traditional tumor-node-metastasis system or isolated histologic parameters. The need for neck node dissection can be predicted depending on the scores obtained.
Arora A, Husain N, Bansal A, et al. Development of a new outcome prediction model in early-stage squamous cell carcinoma of the oral cavity based on histopathologic parameters with multivariate analysis: the Aditi-Nuzhat Lymph-node Prediction Score (ANLPS) system. Am J Surg Pathol. 2017;41:950–960.
Correspondence: Dr. Nuzhat Husain at drnuzhathusain@hotmail.com
Clinicopathological and molecular characterization of SMARCA4-deficient thoracic sarcomas
A growing number of studies suggest critical tumor-suppressor roles for the SWI/SNF chromatin remodeling complex in a variety of human cancers. The recent discovery of SMARCA4-deficient thoracic sarcomas has added to the list of tumor groups with the SMARCA4 inactivating mutation. To better characterize these tumors and establish their nosological status, the authors undertook a clinicopathological and molecular analysis of 12 SMARCA4-deficient thoracic sarcomas and compared them with three potentially related disease entities. The studies included 11 men and one woman with SMARCA4-deficient thoracic sarcomas (ages, 27–82 years; median, 39 years). Most of the patients had heavy smoking exposure and pulmonary emphysema/bullae. The primary tumors were large and involved the thoracic region in all cases and simultaneously affected the abdominal cavity in three cases. The patients followed a rapid course, with a median survival of seven months. Histologically, all tumors showed diffuse sheets of mildly dyscohesive, relatively monotonous, and undifferentiated epithelioid cells with prominent nucleoli. Immunohistochemically, all tumors demonstrated a complete absence (eight cases) or diffuse severe reduction (four cases) of SMARCA4 expression. Cytokeratin, CD34, SOX2, SALL4, and p53 were expressed in six of 12, 10 of 12, 10 of 12, 10 of 12, and seven of 10 cases, respectively. SMARCA2 expression was deficient in 11 of 12 cases, and none (zero of eight) expressed claudin-4. Targeted sequencing was performed in five cases and demonstrated the inactivating SMARCA4 mutation in each case. It also uncovered alterations in TP53 (five of five), NF1 (two of five), CDKN2A (two of five), KRAS (one of five), and KEAP1 (one of five), among other genes. Comparative analysis supported the distinctiveness of SMARCA4-deficient thoracic sarcomas, as they were distinguishable from 13 malignant rhabdoid tumors, 15 epithelioid sarcomas, and 12 SMARCA4-deficient lung carcinomas based on clinicopathological and immunohistochemical grounds. SMARCA4-deficient thoracic sarcomas constitute a unique, highly lethal entity that requires full recognition and differentiation from other epithelioid malignancies involving the thoracic region.
Yoshida A, Kobayashi E, Kubo T, et al. Clinicopathological and molecular characterization of SMARCA4-deficient thoracic sarcomas with comparison to potentially related entities. Mod Pathol. 2017;30:797–809.
Correspondence: Dr. A. Yoshida at akyoshid@ncc.go.jp