CAP TODAY Pathology/Laboratory Medicine/Laboratory Management
Editors: Michael Cibull, MD, professor emeritus, University of Kentucky College of Medicine, Lexington; Rouzan Karabakhtsian, MD, PhD, associate professor of pathology, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY; Thomas Cibull, MD, dermatopathologist, Evanston Hospital, NorthShore University HealthSystem, Evanston, Ill.; and Rachel Stewart, DO, resident physician, Department of Pathology and Laboratory Medicine, University of Kentucky.
Digital image analysis versus manual biomarker assessment in breast cancer
Clinical and cost impact of EGFR and ALK testing in early stage NSCLC
Switch/sucrose nonfermenting complex protein expression in an aggressive endometrial cancer
Immune microenvironment of breast ductal carcinoma in situ
Adverse histological features in malignant colorectal polyps
Use of ancillary molecular analysis for diagnosis of soft tissue tumors
Digital image analysis versus manual biomarker assessment in breast cancer
Digital image analysis versus manual biomarker assessment in breast cancer
In the spectrum of breast cancers, categorization according to the four-gene expression-based subtypes luminal A, luminal B, HER2 enriched, and basal-like is the method of choice for prognostic and predictive value. Because gene-expression assays are not yet universally available, routine immunohistochemical stains act as surrogate markers for these subtypes. Therefore, the congruence of surrogate markers and gene-expression tests is of utmost importance. In this study, three cohorts of primary breast cancer specimens (total, n=436) with up to 28 years of survival data were scored for Ki-67, estrogen receptor, progesterone receptor, and HER2 status manually and by digital image analysis. The results were then compared for sensitivity and specificity for the luminal B subtype, concordance to PAM50 assays in subtype classification, and prognostic power. The Visiopharm Integrator digital image analysis system was used. Digital image analysis outperformed manual scoring in terms of sensitivity and specificity for the luminal B subtype, widely considered the most challenging distinction in surrogate subclassification, and produced slightly better concordance and Cohen’s κ agreement with PAM50 gene-expression assays. Manual biomarker scores and digital image analysis essentially matched each other for Cox regression hazard ratios for all-cause mortality. When the Nottingham combined histologic grade (Elston-Ellis) was used as a prognostic surrogate, stronger Spearman’s rank-order correlations were produced by digital image analysis. The prognostic value of Ki-67 scores in terms of likelihood ratio χ2 (LR χ2) was higher for digital image analysis that also added significantly more prognostic information to the manual scores (LR–∆χ2). The authors concluded that the digital image analysis system they evaluated was, in most aspects, a superior alternative to manual biomarker scoring. It also has the potential to reduce time consumption for pathologists since many of the steps in the workflow are automatic or manageable without pathological expertise.
Stålhammar G, Fuentes Martinez N, Lippert M, et al. Digital image analysis outperforms manual biomarker assessment in breast cancer. Mod Pathol. 2016;29:318–329.
Correspondence: Dr. G. Stålhammar at gustav.stalhammar@ki.se
Clinical and cost impact of EGFR and ALK testing in early stage NSCLC
Although epidermal growth factor receptor- and anaplastic lymphoma kinase-directed therapies are not approved for patients with early stage non-small cell lung carcinoma, many institutions perform epidermal growth factor receptor (EGFR) and anaplastic lymphoma kinase (ALK) testing for all patients with this disease at the time of initial diagnosis. Consensus guidelines recommend EGFR testing and suggest ALK testing at the time of initial diagnosis for patients with advanced disease. The authors conducted a study to examine the cost and clinical impact of EGFR and ALK testing of patients with early stage non-small cell lung carcinoma (NSCLC). They reviewed the records from all patients with a diagnosis of NSCLC made on a nonresection specimen at their institution during calendar-year 2012 and performed a cost analysis. Of 133 patients, 47 (35 percent) had early stage (stage one or two) disease and 86 (65 percent) had locally advanced (stage three) or advanced (stage four) disease at presentation. Eight of the 47 patients (17 percent) with early stage disease had progression or recurrence during 18 to 30 months of follow-up, and six of the eight (75 percent) had pathologic confirmation of progression or recurrence. The estimated additional cost of EGFR and ALK testing for all patients newly diagnosed with NSCLC at the authors’ institution was $75,200 per year, compared to testing only patients with locally advanced and advanced stage disease. The authors concluded that the cost of universal molecular testing of NSCLC is substantial. EGFRand ALK testing of patients with early stage disease appears to have negligible clinical impact since most patients do not have disease recurrence or progression. Those whose disease recurs or progresses typically undergo rebiopsy. The authors’ findings do not support the practice of universal EGFR and ALK testing in NSCLC at the time of initial diagnosis.
Sauter JL, Butnor KJ. Clinical and cost implications of universal versus locally advanced-stage and advanced-stage-only molecular testing for epidermal growth factor receptor mutations and anaplastic lymphoma kinase rearrangements in non-small cell lung carcinoma: a tertiary academic institution experience. Arch Pathol Lab Med. 2016;140:358–361.
Correspondence: Dr. Jennifer L. Sauter at sauter.jennifer@mayo.edu
Switch/sucrose nonfermenting complex protein expression in an aggressive endometrial cancer
Dedifferentiated endometrial carcinoma is an aggressive type of endometrial cancer that contains a mix of low-grade endometrioid and undifferentiated carcinoma components. The authors performed targeted sequencing of eight dedifferentiated carcinomas and identified somatic frameshift/nonsense mutations in SMARCA4, a core ATPase of the switch/sucrose nonfermenting (SWI/SNF) complex, in the undifferentiated components of four tumors. Immunohistochemical analysis confirmed the loss of SMARCA4 in the undifferentiated component of these four SMARCA4-mutated cases, whereas the corresponding low-grade endometrioid component showed retained SMARCA4 expression. An expanded survey of other members of the SWI/SNF complex showed SMARCB1 loss in the undifferentiated component of two SMARCA4-intact tumors, and all SMARCA4- or SMARCB1-deficient tumors showed concomitant loss of expression of SMARCA2. The authors subsequently examined the expression of SMARCA2, SMARCA4, and SMARCB1 in an additional set of 22 centrally reviewed dedifferentiated carcinomas and 31 grade three endometrioid carcinomas. Combining the results from the index and expansion set, 15 of 30 (50 percent) of the dedifferentiated carcinomas examined showed concurrent SMARCA4 and SMARCA2 loss (37 percent) or concurrent SMARCB1 and SMARCA2 loss (13 percent) in the undifferentiated component. The loss of SMARCA4 or SMARCB1 was mutually exclusive. All 31 grade three endometrioid carcinomas showed intact expression of these core SWI/SNF proteins. The majority (73 percent) of the SMARCA4/SMARCA2-deficient and half of the SMARCB1/SMARCA2-deficient undifferentiated compo-nent developed in a mismatch repair-deficient molecular context. The spatial association observed between SWI/SNF protein loss and histologic dedifferentiation suggests that inactivation of these core SWI/SNF proteins may contribute to the development of dedifferentiated endometrial carcinoma.
Karnezis AN, Hoang LN, Coatham M, et al. Loss of switch/sucrose non-fermenting complex protein expression is associated with dedifferentiation in endometrial carcinomas. Mod Pathol. 2016;29:302–314
Correspondence: Dr. C. H. Lee at chlee2@ualberta.ca
Immune microenvironment of breast ductal carcinoma in situ
The host immune response plays a key role in breast cancer progression and response to therapy. However, relative to primary invasive breast cancers, the immune milieu of breast ductal carcinoma in situ (DCIS) is less understood. The authors conducted a study in which they profiled tumor infiltrating lymphocytes and expression of the immune checkpoint ligand programmed death-ligand 1 (PD-L1) in 27 cases of DCIS with known estrogen receptor (ER), progesterone receptor, and human epidermal growth factor receptor 2 (HER2) expression using tissue microarrays. Twenty-four cases were pure DCIS and three had associated invasive ductal carcinoma. Tumors were stained by immunohistochemistry for PD-L1 and the lymphocyte markers CD3, CD4, CD8, FoxP3, and CD20. The expression of PD-L1 by DCIS carcinoma cells and tumor infiltrating lymphocytes was determined, and the average tumor infiltrating lymphocytes per high power field were manually scored. None of the DCIS cells expressed PD-L1, but 81 percent of DCIS lesions contained PD-L1–positive tumor infiltrating lymphocytes. DCIS with moderate-diffuse tumor infiltrating lymphocytes was more likely to have PD-L1–positive tumor infiltrating lymphocytes (P=.004). Tumor infiltrating lymphocytes with high levels of PD-L1 expression (more than 50 percent cells) were seen only in triple-negative DCIS (P=.0008), and PD-L1 tumor infiltrating lymphocytes were seen only in ER–positive/HER2–negative DCIS (P=.12). The presence of PD-L1–positive tumor infiltrating lymphocytes was associated with a younger mean patient age (P=.01). Further characterization of the DCIS immune microenvironment may identify useful targets for immune-based therapy and breast cancer prevention.
Thompson E, Taube JM, Elwood H, et al. The immune microenvironment of breast ductal carcinoma in situ. Mod Pathol. 2016;29:249–258.
Correspondence: Dr. A. Cimino-Mathews at acimino1@jhmi.edu or Dr. L. A. Emens at emensle@jhmi.edu
Adverse histological features in malignant colorectal polyps
Screening colonoscopy has led to more colorectal carcinomas being identified at an early stage and potentially being curable by endoscopic resection. The authors examined the clinical and histological features of a contemporary series of malignant colorectal polyps (MCPs) with subsequent surgical resection. They conducted a retrospective study on a consecutive series of MCPs from 239 patients, predominantly male (57.7 percent) and a median age of 66 years, and assessed histological parameters associated with residual disease on the surgical specimens. Median MCP size was 18.6 mm, with 23.1 percent of polyps measuring 10 mm or less. From the 140 surgical resection specimens, residual disease was identified in 20 cases, including 12 cases with metastatic lymph nodes and/or nine cases with residual carcinoma in the large bowel wall. Histological parameters associated with nodal metastases were greater width and greater depth of the invasive component (P=.001 and .006, respectively), poor differentiation (P=.003), and cribriform pattern (P=.01). The risk of nodal metastases was 23.3 percent if two or three of these features were identified, while it was zero and 4.5 percent, respectively, if none or one was present. A positive margin was not associated with nodal metastasis and might be adequately treated by local endoscopic resection. The authors concluded that surgical resection should be recommended if two or more of these adverse histological features are present and may be warranted if one feature is present. A positive margin may require additional local resection, but not necessarily surgery, if no other adverse factors are found.
Brown IS, Bettington ML, Bettington A, et al. Adverse histological features in malignant colorectal polyps: a contemporary series of 239 cases. J Clin Pathol. 2016;69:292–299.
Correspondence: Dr. Ian S. Brown at ianbrown@envoi.com.au
Use of ancillary molecular analysis for diagnosis of soft tissue tumors
The histological diagnosis of soft tissue tumors can be difficult, sometimes requiring a combination of morphology, immunophenotype, and ancillary molecular tests. Many soft tissue tumors (STTs) are associated with characteristic genetic aberrations that can be assessed using FISH, RT-PCR, or mutational analysis. The authors previously studied the practicality and sensitivity of using these modalities for part of the routine diagnosis of STT in paraffin-embedded material and now revisit the subject in light of further experience in this field. Two hundred consecutive cases from 2013 that had undergone FISH, RT-PCR, or mutational analysis were assessed to evaluate those tests’ diagnostic utility compared with preliminary histological assessment. A total of 218 FISH, 91 RT-PCR, and 43 mutational analysis tests were performed. Compared with the previous study, FISH for MDM2 amplification in possible well-differentiated/dedifferentiated liposarcomas and mutational analysis for assessing KIT, PDGFR, and BRAF mutations made up a large proportion of the workload (107 and 43 tests, respectively). As in the previous study, alveolar rhabdomyosarcoma showed the best FISH:RT-PCR concordance. Unlike previously, RT-PCR showed marginally higher sensitivity than FISH (78.9 and 76.9 percent, respectively) while continuing to demonstrate higher specificity (90.9 and 84.3 percent, respectively). RT-PCR again showed an increased failure rate (5.5 percent; one percent for FISH). The authors concluded that in STT diagnosis, both RT-PCR and FISH offer advantages in specific contexts. These ancillary molecular tests are important tools in defining and excluding diagnoses of STT, which is crucial in determining prognosis and guiding appropriate patient management.
Vroobel K, Gonzalez D, Wren D, et al. Ancillary molecular analysis in the diagnosis of soft tissue tumours: reassessment of its utility at a specialist centre. J Clin Pathol. 2016;69(6):505–510.
Correspondence: Dr. Khin Thway at khin.thway@rmh.nhs.uk