Pancreatic intraepithelial neoplasia in the background of invasive ductal carcinoma of the pancreas as a prognostic factor

CT findings and clinical effects of high grade pancreatic intraepithelial neoplasia in patients with intraductal papillary mucinous neoplasms

PURPOSE

To investigate the common CT findings of high-grade (HG) PanIN and clinical effects in the remnant pancreas in patients with intraductal papillary mucinous neoplasm (IPMN) of the pancreas.

MATERIALS AND METHODS

Two hundred fifty-one patients with surgically confirmed IPMNs (118 malignant [invasive carcinoma/high-grade dysplasia] and 133 benign [low-grade dysplasia]) were retrospectively enrolled. The grade of PanIN (233 absent/low-grade and 18 high-grade) was recorded, and all patients underwent serial CT follow-up before and after surgery. Two radiologists analyzed CT findings of high-risk stigmata or worrisome features according to 2017 international consensus guidelines. They also analyzed tumor recurrence on serial follow-up CT after surgery. Statistical analyses were performed to identify significant predictors and clinical impact on postoperative outcomes of HG PanIN.

RESULTS

PanIN grade showed a significant association with IPMN grade (p = 0.012). Enhancing mural nodules ≥5 mm, abrupt main pancreatic duct (MPD) changes with distal pancreatic atrophy, increased mural nodule size and MPD diameter were common findings in HG PanIN (P<0.05). In multivariate analysis, abrupt MPD change with distal pancreatic atrophy (odds ratio (OR) 6.59, 95% CI: 2.32-18.72, <0.001) and mural nodule size (OR, 1.05; 95% CI, 1.02-1.08, 0.004) were important predictors for HG PanIN. During postoperative follow-up, HG PanIN (OR, 4.98; 95% CI, 1.22-20.33, 0.025) was significantly associated with cancer recurrence in the remnant pancreas.

CONCLUSION

CT can be useful for predicting HG PanIN using common features, such as abrupt MPD changes and mural nodules. In HG PanIN, extra caution is needed to monitor postoperative recurrence during follow-up.

Pre-Operative Imaging and Pathological Diagnosis of Localized High-Grade Pancreatic Intra-Epithelial Neoplasia without Invasive Carcinoma

Pancreatic ductal adenocarcinoma (PDAC) arises from precursor lesions, such as pancreatic intra-epithelial neoplasia (PanIN) and intraductal papillary mucinous neoplasm (IPMN). The prognosis of high-grade precancerous lesions, including high-grade PanIN and high-grade IPMN, without invasive carcinoma is good, despite the overall poor prognosis of PDAC. High-grade PanIN, as a lesion preceding invasive PDAC, is therefore a primary target for intervention. However, detection of localized high-grade PanIN is difficult when using standard radiological approaches. Therefore, most studies of high-grade PanIN have been conducted using specimens that harbor invasive PDAC. Recently, imaging characteristics of high-grade PanIN have been revealed. Obstruction of the pancreatic duct due to high-grade PanIN may induce a loss of acinar cells replaced by fibrosis and lobular parenchymal atrophy. These changes and additional inflammation around the branch pancreatic ducts (BPDs) result in main pancreatic duct (MPD) stenosis, dilation, retention cysts (BPD dilation), focal pancreatic parenchymal atrophy, and/or hypoechoic changes around the MPD. These indirect imaging findings have become important clues for localized, high-grade PanIN detection. To obtain pre-operative histopathological confirmation of suspected cases, serial pancreatic-juice aspiration cytologic examination is effective. In this review, we outline current knowledge on imaging characteristics of high-grade PanIN.

Aggressive PDACs Show Hypomethylation of Repetitive Elements and the Execution of an Intrinsic IFN Program Linked to a Ductal Cell of Origin

Pancreatic ductal adenocarcinoma (PDAC) is characterized by extensive desmoplasia, which challenges the molecular analyses of bulk tumor samples. Here we FACS-purified epithelial cells from human PDAC and normal pancreas and derived their genome-wide transcriptome and DNA methylome landscapes. Clustering based on DNA methylation revealed two distinct PDAC groups displaying different methylation patterns at regions encoding repeat elements. Methylation^low tumors are characterized by higher expression of endogenous retroviral transcripts and double-stranded RNA sensors, which lead to a cell-intrinsic activation of an interferon signature (IFNsign). This results in a protumorigenic microenvironment and poor patient outcome. Methylation^low/IFNsign^high and Methylation^high/IFNsign^low PDAC cells preserve lineage traits, respective of normal ductal or acinar pancreatic cells. Moreover, ductal-derived Kras ^G12D/Trp53 ^-/- mouse PDACs show higher expression of IFNsign compared with acinar-derived counterparts. Collectively, our data point to two different origins and etiologies of human PDACs, with the aggressive Methylation^low/IFNsign^high subtype potentially targetable by agents blocking intrinsic IFN signaling. SIGNIFICANCE: The mutational landscapes of PDAC alone cannot explain the observed interpatient heterogeneity. We identified two PDAC subtypes characterized by differential DNA methylation, preserving traits from normal ductal/acinar cells associated with IFN signaling. Our work suggests that epigenetic traits and the cell of origin contribute to PDAC heterogeneity.This article is highlighted in the In This Issue feature, p. 521.

Concomitant Intraductal Papillary Mucinous Neoplasm in Pancreatic Ductal Adenocarcinoma Is an Independent Predictive Factor for the Occurrence of New Cancer in the Remnant Pancreas

OBJECTIVE

To determine the factors predicting the subsequent development of pancreatic ductal adenocarcinoma in remnant pancreas (PDAC-RP) after partial pancreatectomy for PDAC.

SUMMARY BACKGROUND DATA

PDAC-RP after partial pancreatectomy for PDAC is currently not so rare because of improved prognosis of PDAC patients due to recent advances in surgical techniques and adjuvant therapy. However, the predictive factors related to PDAC-RP remain unknown.

METHODS

We retrospectively reviewed the clinicopathological data of a consecutive series of 379 patients with PDAC treated by partial pancreatectomy between 1992 and 2015; 14 patients (3.69%) had PDAC-RP. Clinicopathological variables were compared between PDAC-RP and non-PDAC-RP.

RESULTS

In univariate analysis, concomitant intraductal papillary mucinous neoplasm (IPMN) (P = 0.0005), cancer location (body/tail) (P = 0.0060), and lower T factor in UICC (P = 0.0039) were correlated with PDAC-RP development. Multivariate analysis revealed concomitant IPMN (P = 0.0135) to be an independent predictive factor for PDAC-RP. PDAC concomitant with IPMN had higher cumulative incidence of PDAC-RP (47.5%/10 yrs) than PDAC without IPMN (9.96%/10 yrs) (P = 0.0071). Moreover, the density of pancreatic intraepithelial neoplasia lesions in the background pancreas of cases of PDAC concomitant with IPMN (1.86/cm) was higher than that of cases of PDAC without IPMN (0.91/cm) (P = 0.0007).

CONCLUSIONS

Concomitant IPMN in PDAC is an independent predictive factor for the development of new PDAC in remnant pancreas. Cancer susceptibility of remnant pancreas after resection for PDAC concomitant with IPMN is probably due to an increased density of pancreatic intraepithelial neoplasia lesions.

Cell of origin affects tumour development and phenotype in pancreatic ductal adenocarcinoma

OBJECTIVE

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive tumour thought to arise from ductal cells via pancreatic intraepithelial neoplasia (PanIN) precursor lesions. Modelling of different genetic events in mice suggests both ductal and acinar cells can give rise to PDAC. However, the impact of cellular context alone on tumour development and phenotype is unknown.

DESIGN

We examined the contribution of cellular origin to PDAC development by inducing PDAC-associated mutations, Kras^G12D expression and Trp53 loss, specifically in ductal cells (Sox9CreER;Kras^LSL-G12D;Trp53^flox/flox ('Duct:KP^cKO ')) or acinar cells (Ptf1a^CreER;Kras^LSL-G12D;Trp53^flox/flox ('Acinar:KP^cKO ')) in mice. We then performed a thorough analysis of the resulting histopathological changes.

RESULTS

Both mouse models developed PDAC, but Duct:KP^cKO mice developed PDAC earlier than Acinar:KP^cKO mice. Tumour development was more rapid and associated with high-grade murine PanIN (mPanIN) lesions in Duct:KP^cKO mice. In contrast, Acinar:KP^cKO mice exhibited widespread metaplasia and low-grade as well as high-grade mPanINs with delayed progression to PDAC. Acinar-cell-derived tumours also had a higher prevalence of mucinous glandular features reminiscent of early mPanIN lesions.

CONCLUSION

These findings indicate that ductal cells are primed to form carcinoma in situ that become invasive PDAC in the presence of oncogenic Kras and Trp53 deletion, while acinar cells with the same mutations appear to require a prolonged period of transition or reprogramming to initiate PDAC. Our findings illustrate that PDAC can develop in multiple ways and the cellular context in which mutations are acquired has significant impact on precursor lesion initiation, disease progression and tumour phenotype.

Clinical significance of pancreatic intraepithelial neoplasia in resectable pancreatic cancer on survivals

Purpose

Noninvasive precursor lesions for pancreatic adenocarcinoma include pancreatic intraepithelial neoplasia (PanIN), intraductal papillary mucinous neoplasm, and mucinous cystic neoplasm. PanIN is often found synchronously adjacent to resected pancreatic ductal adenocarcinoma (PDAC) tumors. However, its prognostic significance on outcome after PDAC resection is unknown. The purpose of the current study was to determine if the presence of PanIN has a prognostic or predictive effect on survival after resection for PDAC with curative intent.

Methods

We retrospectively reviewed the clinicopathologic data of patients who underwent pancreatectomy for PDAC from January 2002 to January 2013. Intraductal papillary mucinous lesions and mucinous cystic neoplasms were excluded. All available postoperative imaging and clinical follow-up data were reviewed.

Results

There were 95 patients who underwent pancreatectomy. Tumors were most commonly located in the pancreas head and as such pancreaticoduodenectomy was the most commonly performed operation. The median tumor size was 3.2 cm. An absence of PanIN lesions was identified in 39 patients (41%). Of the patients with PanIN lesions, high-grade PanIN (grade 3) was the most common type (64.3%) followed by grade 2 (28.6%). There was no significant difference in overall survival or disease-free survival between the non-PanIN and PanIN groups.

Conclusion

The presence or absence of PanIN lesions did not affect survival in patients undergoing resection for pancreatic cancer. However, patients with high-grade PanINs tended to have better overall survival. Larger studies with longer follow up are needed to accurately determine its clinical significance.

Diversity of Precursor Lesions For Pancreatic Cancer: The Genetics and Biology of Intraductal Papillary Mucinous Neoplasm

Pancreatic ductal adenocarcinoma (PDA), one of the most lethal cancers worldwide, is associated with two main types of morphologically distinct precursors—pancreatic intraepithelial neoplasia (PanIN) and intraductal papillary mucinous neoplasm (IPMN). Although the progression of PanIN into invasive cancer has been well characterized, there remains an urgent need to understand the biology of IPMNs, which are larger radiographically detectable cystic tumors. IPMNs comprise a number of subtypes with heterogeneous histopathologic and clinical features. Although frequently remaining benign, a significant proportion exhibits malignant progression. Unfortunately, there are presently no accurate prognosticators for assessing cancer risk in individuals with IPMN. Moreover, the fundamental mechanisms differentiating PanIN and IPMN remain largely obscure, as do those that distinguish IPMN subtypes. Recent studies, however, have identified distinct genetic profiles between PanIN and IPMN, providing a framework to better understand the diversity of the precursors for PDA. Here, we review the clinical, biological, and genetic properties of IPMN and discuss various models for progression of these tumors to invasive PDA.

High-grade pancreatic intraepithelial lesions: prevalence and implications in pancreatic neoplasia

BACKGROUND

High-grade pancreatic intraepithelial neoplasia (PanIN-3), a precursor of pancreatic ductal adenocarcinoma (PDAC), is not universally detected in resected pancreatic neoplasms. We sought to determine the prevalence and prognostic relevance of PanIN-3 lesions in primary surgical resections of PDACs and intraductal papillary mucinous neoplasms (IPMNs).

METHODS

A retrospective review of a tertiary care center pathology database (1/2000-6/2014) was performed. Demographics, imaging, pathology, disease-recurrence, and survival data were reviewed.

RESULTS

A total of 458 patients who underwent primary pancreatic resection were included. "PanIN-3" lesions were found in 74 (16.2%) patients who either had PDAC (n=67) or main duct (MD)-IPMN (n=7). Among IPMN-MDs, PanIN-3 lesions were exclusively found in those with pathological evidence of chronic pancreatitis. For PDACs, the median overall survival (OS) for pancreata with PanIN-3 lesions was significantly better than those without (OS 1.12 years, inter-quartile range [IQR] 0.72, 2.05 years vs OS 0.86 years, IQR 0.64, 1.60 years respectively; P=0.04). Multivariate Cox regression analysis demonstrated that the presence of PanIN-3 lesions was associated with a reduced risk of death (HR=0.43; 95% CI: 0.23-0.82; P=0.01).

CONCLUSIONS

Following primary resection of pancreatic adenocarcinoma, the lower survival observed in patients without PanIN-3 lesions might suggest a state of complete or accelerated transformation. Further investigations are necessary to validate these findings that might impact disease prognosis and management.

MicroRNA-506 is up-regulated in the development of pancreatic ductal adenocarcinoma and is associated with attenuated disease progression

BACKGROUND

MicroRNA-506 (miR-506) has been reported to function in several tumors as a tumor suppressor gene or oncogene. However, the expression and role of miR-506 in pancreatic ductal adenocarcinoma (PDAC) remains unclear. In this study, we aimed to evaluate the phenotype of miR-506 in PDAC.

METHODS

Using miRNA in situ hybridization, we examined the expression of miR-506 in 113 PDACs and 87 paired normal pancreatic tissues. We evaluated miR-506 expression in PDAC cells, normal pancreatic ducts, and acinus/islands, and we analyzed the associations between miR-506 expression and the clinicopathologic characteristics of PDAC patients.

RESULTS

miR-506 expression was higher in PDAC than in matched normal pancreatic ductal cells (P < 0.001). On the other hand, the combined group of well and moderately differentiated PDACs showed higher levels of miR-506 than the poorly differentiated ones (P = 0.023). Moreover, miR-506 expression was negatively associated with pathologic T category (P = 0.004) and lymph node metastasis (P = 0.033), suggesting that miR-506 might inhibit the progression of PDAC.

CONCLUSIONS

Our results suggest that miR-506 either plays a role as an oncogene in the tumorigenesis and a tumor suppressor in the progression or serves as a house-keeping, tumor-suppressing miRNA, whose expression can be activated by oncogenic signals in early development to hinder the progression of PDAC.