How reliable is the Ki-67 cytological index in grading pancreatic neuroendocrine tumors? A meta-analysis

Pancreatic adenocarcinoma and pancreatic high-grade neuroendocrine carcinoma: two sides of the moon

Pancreatic adenocarcinoma is the seventh leading cause of cancer death in the world and the most common type pf pancreatic cancer. Unfortunately, less than 20% of patients are surgically resectable and the great majority of cases are treated with palliative chemotherapy with unsatisfactory results. No targeted agents or personalized approaches have been validated in the last decades. On the other side, neuroendocrine neoplasms of the pancreas are generally considered indolent tumours. However, high-grade neuroendocrine carcinoma is a rare subtype of neuroendocrine neoplasm of the pancreas (accounting up to 10% of the neuroendocrine neoplasms of the pancreas), with particularly aggressive behaviour and poor prognosis. Even in this case, the treatment is represented by palliative chemotherapy with dismal results and no personalized therapies are available, so far. Notably, the quality of life of these patients is disappointingly low and the future perspectives of more personalized diagnostic and therapeutic strategies are scarce. In this review, we discuss relevant and current information on epidemiology, pathology, diagnosis, clinical presentation, treatment and ongoing clinical trials of these two entities, in order to illustrate the two sides of the moon.

Endoscopic ultrasound-guided side-fenestrated needle biopsy sampling is sensitive for pancreatic neuroendocrine tumors but inadequate for tumor grading: a prospective study

Accurate pretreatment grading of pancreatic neuroendocrine tumors (PanNETs) is important to guide patient management. We aimed to evaluate endoscopic ultrasound-guided fine needle biopsy sampling (EUS-FNB) for the preoperative diagnosis and grading of PanNETs. In a tertiary-center setting, patients with suspected PanNETs were prospectively subjected to 22-gauge, reverse-bevel EUS-FNB. The EUS-FNB samples (Ki-67_EUS) and corresponding surgical specimens (Ki-67_SURG) were analyzed with Ki-67 indexing and thereafter tumor grading, (GRADE_EUS) and (GRADE_SURG) respectively. In total 52 PanNET-patients [median age: 66 years; females: 25/52; surgical resection 22/52 (42%)] were included. EUS-FNB was diagnostic in 44/52 (85%). In 42 available FNB-slides, the median neoplastic cell count was 1034 (IQR: 504-3667) with 32/42 (76%), 22/42 (52%), and 14/42 (33%) cases exceeding 500, 1000, and 2000 neoplastic cells respectively. Ki-67_SURG was significantly higher compared to Ki-67_EUS with a moderate correlation comparing Ki-67_EUS and Ki-67_SURG (Pearson r = 0.60, r² = 0.36, p = 0.011). The GRADE_EUS had a weak level of agreement (κ = 0.08) compared with GRADE_SURG. Only 2/12 (17%) G2-tumors were correctly graded in EUS-FNB-samples. EUS-guided fine needle biopsy sampling is sensitive for preoperative diagnosis of PanNET but biopsy quality is relatively poor. Therefore, the approach seems suboptimal for pretreatment grading of PanNET.

Endoscopic ultrasound-guided fine-needle aspiration for the diagnosis and grading of pancreatic neuroendocrine tumors: a retrospective analysis of 110 cases

BACKGROUND

Data on the reliability of the Ki-67 index and grading calculations from endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) of pancreatic neuroendocrine tumors (PanNETs) are controversial. We aimed to assess the accuracy of these data compared with histology.

METHODS

Cytological analysis from EUS-FNA in patients with suspected PanNETs (n = 110) were compared with resection samples at a single institution. A minimum of 2000 cells were considered to be adequate for grading. Correlation and agreement between cytology and histology in grading and Ki-67 values, respectively, were investigated. Secondary outcomes included the diagnostic performance of EUS-FNA.

RESULTS

EUS-FNA samples were adequate for PanNET diagnosis and PanNET grading in 98/110 (89.1 %) and 77/110 (70.0 %) patients, respectively; thus, 77 samples were adequate for comparing cytology vs. histology. There were 67 (62.0 %), 40 (36.4 %), and 1 (0.9 %) patients with a final diagnosis of G1, G2, and G3 tumors, respectively. EUS-FNA grading was concordant with surgical pathology in 81.8 % of patients; under- and overgrading occurred in 15.6 % and 2.6 %, respectively. The overall level of agreement for grading was moderate (Cohen's κ = 0.59, 95 % confidence interval [CI] 0.34 - 0.78). Spearman's rho for Ki-67 in tumors ≤ 20 mm and > 20 mm was strong and moderate, respectively (rho = 0.68, 95 %CI 0.47 - 0.83; rho = 0.59, 95 %CI 0.35 - 0.75). The Bland - Altman plot showed that the Ki-67 values were comparable and reproducible between the two measurements.

CONCLUSIONS

Although they were not available for a significant number of patients, grading and Ki-67 values from cytology correlated with histology moderately to strongly.

Pathologic interpretation of endoscopic ultrasound-guided fine needle aspiration cytology/biopsy for pancreatic lesions

Pathologic interpretation of endoscopic ultrasound–guided fine needle aspiration (EUS-FNA) cytology/biopsy specimens is one of the most challenging tasks in cytology and surgical pathology practice, as the procedure often yields minimal amounts of diagnostic material and contains contaminants, such as blood cells and normal intestinal mucosa. EUS-FNA cytology/biopsy will nevertheless become a more popular procedure for evaluation of various pancreatic lesions because they are difficult to approach with conventional endoscopic procedures. Pathologists should understand the structural differences and limitations of EUS-FNA that make pathologic diagnosis difficult. Ancillary tests are available for differential diagnosis of EUS-FNA for various pancreatic lesions. Immunostains are the most commonly used ancillary tests, and pathologists should able to choose the necessary panel for differential diagnosis. Pathologists should review clinical history and radiologic and/or EUS findings before selecting an immunostain panel and making a pathologic diagnosis. In addition, one’s threshold of malignancy should be adjusted according to the appropriate clinical setting to avoid under-evaluation of pathologic diagnoses. Clinico-pathologic correlation is essential in pathologic evaluation of EUS-FNA for pancreatic lesions. Pathologists can reduce errors by correlating clinical and radiologic findings when evaluating EUS-FNA. Some molecular tests can be applied in differential diagnosis of pancreatic neoplastic and cystic lesions. Molecular data should be used as supportive evidence of a specific disease entity, rather than direct evidence, and should be correlated with clinico-pathologic findings to avoid errors in pathologic diagnosis.

A Novel Validated Recurrence Risk Score to Guide a Pragmatic Surveillance Strategy After Resection of Pancreatic Neuroendocrine Tumors: An International Study of 1006 Patients

OBJECTIVE

Despite heterogeneous biology, similar surveillance schemas are utilized after resection of all pancreatic neuroendocrine tumors (PanNETs). Given concerns regarding excess radiation exposure and financial burden, our aim was to develop a prognostic score for disease recurrence to guide individually tailored surveillance strategies.

METHODS

All patients with primary nonfunctioning, nonmetastatic well/moderately differentiated PanNETs who underwent curative-intent resection at 9-institutions from 2000 to 2016 were included (n = 1006). A Recurrence Risk Score (RRS) was developed from a randomly selected derivation cohort comprised of 67% of patients and verified on the validation-cohort comprised of the remaining 33%.

RESULTS

On multivariable analysis, patients within the derivation cohort (n = 681) with symptomatic tumors (jaundice, pain, bleeding), tumors >2 cm, Ki67 >3%, and lymph node (LN) (+) disease had increased recurrence. Each factor was assigned a score based on their weighted odds ratio that formed a RRS of 0 to 10: symptomatic = 1, tumor >2 cm = 2, Ki67 3% to 20% = 1, Ki67 >20% = 6, LN (+) = 1. Patients were grouped into low- (RRS = 0-2; n = 247), intermediate-(RRS = 3-5; n = 204), or high (RRS = 6-10; n = 9)-risk groups. At 24 months, 33% of high RRS recurred, whereas only 2% of low and 14% of intermediate RRS recurred. This persisted in the validation cohort (n = 325).

CONCLUSIONS

This international, novel, internally validated RRS accurately stratifies recurrence-free survival for patients with resected PanNETs. Given their unique recurrence patterns, surveillance intervals of 12, 6, and 3 months are proposed for low, intermediate, and high RRS patients, respectively, to minimize radiation exposure and optimize cost/resource utilization.

Grading by the Ki-67 Labeling Index of Endoscopic Ultrasound-Guided Fine Needle Aspiration Biopsy Specimens of Pancreatic Neuroendocrine Tumors Can Be Underestimated

OBJECTIVES

There is an increasing need for grading with small endoscopic ultrasound-guided fine needle aspiration biopsy (EUS-FNAB) specimens for the proper diagnosis and therapy selection of patients with unresectable pancreatic neuroendocrine tumors (PanNET). However, our understanding of EUS-FNAB specimen grading is limited compared with surgically resected specimens.

METHODS

We retrospectively determined Ki-67 labeling index (LI) of 33 matched EUS-FNAB and surgically resected PanNETs with digital image analyzer. Pairwise grades between the matched biopsy and surgically resected PanNET specimens were compared.

RESULTS

The mean Ki-67 LI was higher in surgically resected PanNET specimens (5.5%) than in biopsy specimens (3.2%; P = 0.022). There was moderate agreement between the Ki-67 LI grades when individually evaluated matched biopsy and resected specimen pairs were compared (κ value = 0.62; P < 0.0001). However, discordance was noted in 6 cases (18%), and all of them were either grade 2 or 3 in resected PanNETs.

CONCLUSIONS

Although Ki-67 LI grading of EUS-FNAB specimens may be concordant with that of matched surgically resected specimens in a large proportion of the PanNET cases, Ki-67 LI grading of EUS-FNAB specimens should be carefully applied in clinical practice because of the possibility of grading underestimation with grade 2 to 3 PanNET cases.

Imaging of pancreatic neuroendocrine tumors: recent advances, current status, and controversies

INTRODUCTION

Recently, there have been a number of advances in imaging pancreatic neuroendocrine tumors (panNETs), as well as other neuroendocrine tumors (NETs), which have had a profound effect on the management and treatment of these patients, but in some cases are also associated with controversies. Areas covered: These advances are the result of numerous studies attempting to better define the roles of both cross-sectional imaging, endoscopic ultrasound, with or without fine-needle aspiration, and molecular imaging in both sporadic and inherited panNET syndromes; the increased attempt to develop imaging parameters that correlate with tumor classification or have prognostic value; the rapidly increasing use of molecular imaging in these tumors and the attempt to develop imaging parameters that correlate with treatment/outcome results. Each of these areas and the associated controversies are reviewed. Expert commentary: There have been numerous advances in all aspects of the imaging of panNETs, as well as other NETs, in the last few years. The advances are leading to expanded roles of imaging in the management of these patients and the results being seen in panNETs/GI-NETs with these newer techniques are already being used in more common tumors.

Utility of rapid on-site evaluation for needle core biopsies and fine-needle aspiration cytology done for diagnosis of mass lesions of the liver

BACKGROUND

Fine-needle aspiration (FNA) and core biopsy (CB) are used to diagnose liver lesions. Rapid onsite evaluation (ROSE) can improve the adequacy of the procedures and help triage diagnostic material appropriately. There are very few studies evaluating the role of ROSE for CB and FNA of mass lesions of the liver.

METHODS

Liver cases with ROSE material from 2007 to 2017 were retrieved and reviewed. The ROSE material was re-evaluated by 2 cytopathologists who were blinded to the final diagnosis. Data including age, number of lesions, number of passes, adequacy assessed at time of procedure, and diagnosis made by cytopathologist on ROSE material at time of re-review was compiled.

RESULTS

A total of 82 cases were identified; 33 were primary lesions (group A) and 49 were metastatic lesions (group B). ROSE done by cytotechnologist at time of procedure showed an adequacy rate of 84%. During re-review of ROSE material by cytopathologists, the overall adequacy rates were similar, although the adequacy rates in group B increased (to 100% from 92%) and it dropped in group A (from 73% to 52%). The overall accuracy rate was 90%. Hepatocellular adenoma, regenerative nodules, well-differentiated hepatocellular carcinoma, and angiosarcoma were not possible to diagnose on smears alone during ROSE.

CONCLUSIONS

ROSE for liver lesions is useful for assessing adequacy. Certain lesions cannot be accurately diagnosed on ROSE alone. ROSE material when assessed by cytopathologist can improve adequacy rate and possibly decrease number of nondiagnostic specimens in group A, though the cost effectiveness needs to be assessed.

Fit-for-Purpose Immunohistochemical Biomarkers

There are two aspects of immunohistochemistry (IHC) that are relevant to practicing pathologist: (1) understanding of IHC biomarker panels that are suitable for diagnostic, prognostic and predictive testing, and (2) understanding of IHC quality assurance (QA), which makes sure that the tests in these panels work as they should. The two aspects are closely linked together and call for collaborative approach between pathologists and IHC laboratory technologists as both need to be involved in developing and maintaining IHC biomarkers that are "fit-for-purpose". This article reviews the most current IHC QA concepts that are imminently material to practicing pathologists with emphasis on challenges that are specific to endocrine pathology.

Can histogram analysis of MR images predict aggressiveness in pancreatic neuroendocrine tumors?

OBJECTIVES

To evaluate MRI derived whole-tumour histogram analysis parameters in predicting pancreatic neuroendocrine neoplasm (panNEN) grade and aggressiveness.

METHODS

Pre-operative MR of 42 consecutive patients with panNEN >1 cm were retrospectively analysed. T1-/T2-weighted images and ADC maps were analysed. Histogram-derived parameters were compared to histopathological features using the Mann-Whitney U test. Diagnostic accuracy was assessed by ROC-AUC analysis; sensitivity and specificity were assessed for each histogram parameter.

RESULTS

ADC_entropy was significantly higher in G2-3 tumours with ROC-AUC 0.757; sensitivity and specificity were 83.3 % (95 % CI: 61.2-94.5) and 61.1 % (95 % CI: 36.1-81.7). ADC_kurtosis was higher in panNENs with vascular involvement, nodal and hepatic metastases (p= .008, .021 and .008; ROC-AUC= 0.820, 0.709 and 0.820); sensitivity and specificity were: 85.7/74.3 % (95 % CI: 42-99.2 /56.4-86.9), 36.8/96.5 % (95 % CI: 17.2-61.4 /76-99.8) and 100/62.8 % (95 % CI: 56.1-100/44.9-78.1). No significant differences between groups were found for other histogram-derived parameters (p >.05).

CONCLUSIONS

Whole-tumour histogram analysis of ADC maps may be helpful in predicting tumour grade, vascular involvement, nodal and liver metastases in panNENs. ADC_entropy and ADC_kurtosis are the most accurate parameters for identification of panNENs with malignant behaviour.

KEY POINTS

• Whole-tumour ADC histogram analysis can predict aggressiveness in pancreatic neuroendocrine neoplasms. • ADC entropy and kurtosis are higher in aggressive tumours. • ADC histogram analysis can quantify tumour diffusion heterogeneity. • Non-invasive quantification of tumour heterogeneity can provide adjunctive information for prognostication.

Redefining the Ki-67 Index Stratification for Low-Grade Pancreatic Neuroendocrine Tumors: Improving Its Prognostic Value for Recurrence of Disease

BACKGROUND

The Ki-67 index is an established prognostic marker for recurrence after resection of pancreatic neuroendocrine tumors (PanNETs) that groups tumors into three categories: low grade (< 3%), intermediate grade (3-20%), and high grade (> 20%). Given that the majority of resected PanNETs have a Ki-67 less than 3%, this study aimed to stratify this group further to predict disease recurrence more accurately.

METHODS

The Ki-67 index was pathologically re-reviewed and scored by a pathologist blinded to all other clinicopathologic variables using tissue microarray blocks made in triplicate. All patients who underwent curative-intent resection of non-metastatic PanNETs at a single institution from 2000 to 2013 were included in the study. The primary outcome was recurrence-free survival (RFS).

RESULTS

Of 113 patients with well-differentiated PanNETs resected, 83 had tissue available for pathologic re-review. The Ki-67 index was lower than 3% for 72 tumors (87%) and between 3 and 20% for 11 tumors (13%). Considering only Ki-67 less than 3%, the tumors were further stratified by Ki-67 into three groups: group A (< 1%, n = 43), group B (1-1.99%, n = 23), and group C (2-2.99%, n = 6). Compared with group A, groups B and C more frequently had advanced T stage (T3: 44% and 67% vs 12%; p = 0.003) and lymphovascular invasion (50% and 83% vs 23%; p = 0.007). Groups B and C had similar 1- and 3-year RFS, both less than group A. After combining groups B and C, a Ki-67 of 1-2.99% was associated with decreased RFS compared with group A (< 1%). This persisted in the multivariable analysis (hazard ratio [HR] 8.6; 95% confidence interval [CI] 1.0-70.7; p = 0.045), with control used for tumor size, margin-positivity, lymph node involvement, and advanced T stage.

CONCLUSIONS

PanNETs with a Ki-67 of 1-2.99% exhibit distinct biologic behavior and earlier disease recurrence than those with a Ki-67 lower than 1%. This new stratification scheme, if externally validated, should be incorporated into future grading systems to guide both surveillance protocols and treatment strategies.