Recent Advances in Pancreatic Cancer Surgery of Relevance to the Practicing Pathologist

A Comprehensive Review of Small Interfering RNAs (siRNAs): Mechanism, Therapeutic Targets, and Delivery Strategies for Cancer Therapy

Small interfering RNA (siRNA) delivery by nanocarriers has been identified as a promising strategy in the study and treatment of cancer. Short nucleotide sequences are synthesized exogenously to create siRNA, which triggers RNA interference (RNAi) in cells and silences target gene expression in a sequence-specific way. As a nucleic acid-based medicine that has gained popularity recently, siRNA exhibits novel potential for the treatment of cancer. However, there are still many obstacles to overcome before clinical siRNA delivery devices can be developed. In this review, we discuss prospective targets for siRNA drug design, explain siRNA drug properties and benefits, and give an overview of the current clinical siRNA therapeutics for the treatment of cancer. Additionally, we introduce the siRNA chemical modifications and delivery systems that are clinically sophisticated and classify bioresponsive materials for siRNA release in a methodical manner. This review will serve as a reference for researchers in developing more precise and efficient targeted delivery systems, promoting ongoing advances in clinical applications.

Advances in the Surgical Treatment of Pancreatic Cancer

Three recent advances in the surgical approach to pancreatic cancer over the past decade have improved both short- and long-term outcomes for patients with nonmetastatic, operable pancreatic cancer. These include (1) minimally invasive pancreatectomy to reduce operative morbidity while adhering to principles of open oncologic resections, (2) neoadjuvant chemotherapy to treat radiographically occult metastatic disease and improve locoregional control, and (3) applying irreversible electroporation as an adjunct to surgery, allowing a fraction of locally advanced pancreatic cancer to be resected.

Clinical Effect of Driver Mutations of KRAS, CDKN2A/P16, TP53, and SMAD4 in Pancreatic Cancer: A Meta-Analysis

Objective: To evaluate the prognostic value of driver mutations in the KRAS, CDKN2A/P16, TP53, and SMAD4 genes in pancreatic cancer to aid in the design of therapeutic strategies. Search Strategy: A systematic search was conducted using PubMed, MEDLINE, Springer, and Cochrane library to identify eligible studies published between January 1990 and June 2018 that reported an association between driver mutations in these genes and survival data. Inclusion Criteria: Articles which passed the primary screen were further scrutinized for the presence of all the following items: (1) cohort studies or case-control studies, evaluating the relationship between driver mutations and cancer; (2) cancer diagnoses clearly proved; and (3) hazard ratios (HR) and 95% confidence intervals (CIs) were characterized by sufficient information. Data Extraction and Analysis: Selection of included articles, data extraction, and methodological quality assessments were, respectively, conducted by two authors. Results: The meta-analysis was composed of 17 studies on the P53, 8 on SMAD4, 7 on CDKN2A/P16, and 2 on KRAS, containing 3373 samples. Our pooled results demonstrated that the patients with overexpression of the P53 (HR = 1.249, 95% CI = 1.003-1.554, p = 0.047), SMAD4 (HR = 1.397, 95% CI = 1.015-1.922, p = 0.040), CDKN2A/P16 (HR = 0.916, 95% CI = 0.583-1.439, p = 0.704), and KRAS (HR = 1.68, 95% CI = 1.27-2.22, p < 0.001) mutations all had poorer overall survival. Conclusion: This systematic review and meta-analysis supports the use of driver mutations in the P53, SMAD4, and KRAS genes as prognostic markers for pancreatic cancer.

Pancreatic Frozen Section Guides Operative Management With Few Deferrals and Errors

CONTEXT.—

Pancreatic adenocarcinoma is the third leading cause of cancer death in the United States. Surgery remains the mainstay of treatment, and frozen section analysis is used to confirm diagnosis and determine resectability and margin status.

OBJECTIVE.—

To evaluate use and accuracy of frozen section and how diagnosis impacts surgical procedure.

DESIGN.—

We reviewed patients with planned pancreatic resections between January 2014 and March 2019 with at least 1 frozen section. Pathology reports including frozen sections, preoperative cytology, and operative notes were reviewed. Frozen sections were categorized by margin, primary pancreatic diagnosis, metastasis, or vascular resectability. The deferral and error rates and surgeons' response were noted.

RESULTS.—

We identified 898 planned pancreatic resections and 221 frozen sections that were performed on 152 cases for 102 margins, 94 metastatic lesions, 20 primary diagnoses, and 5 to confirm vascular resectability. The diagnosis was deferred to permanent sections in 13 of 152 cases (8.6%) on 16 of 221 frozen sections (7.2%): 6 for metastasis, 8 for margins, and 2 for primary diagnosis. Discrepancies/errors were identified in 4 of 152 cases (2.6%) and 4 of 221 frozen sections (1.8%). Surgeon's response was different than expected in 8 of 221 frozen sections (3.6%), but their actions were explained by other intraoperative findings in 6 of 8.

CONCLUSIONS.—

Frozen section remains an important diagnostic tool used primarily for evaluation of margins and metastasis during pancreatectomy. In most cases, a definitive diagnosis is rendered, with occasional deferrals and few errors. Intraoperative findings explain most cases where surgeons act differently than expected based on frozen section diagnosis.

Pancreatic Ductal Adenocarcinoma and Its Precursor Lesions: Histopathology, Cytopathology, and Molecular Pathology

Pancreatic ductal adenocarcinoma is one of the most aggressive malignant neoplasms with poor outcomes. At the time of diagnosis, the disease is usually at an advanced stage and only a minority is eligible for surgical resection. To improve the prognosis, it is essential to diagnose and treat the disease in an early stage before its progression into an invasive disease. This article reviews clinical features, histopathology, cytopathology, and molecular alterations of pancreatic ductal adenocarcinoma and its precursors. Moreover, we review a recently updated two-tier classification system for precursor lesions, new findings in premalignant cystic neoplasms, and recently updated staging criteria for invasive carcinoma based on the Cancer Staging Manual, eighth edition, from the American Joint Committee on Cancer. Finally, we discuss the potential clinical applications of the rapidly growing molecular and genetic information of pancreatic cancer and its precursors.

B7-H3 combats apoptosis induced by chemotherapy by delivering signals to pancreatic cancer cells

Objective

This study aimed to investigate the role of B7-H3 in chemotherapy resistance of pancreatic cancer cells and discover the potential signal transduction pathway and molecular targets involved.

Methods

Immunohistochemical staining and real-time polymerase chain reaction (PCR) were used to determine the expression of B7-H3 in clinical specimens. Clinical data were applied to survival analysis. Phosphoprotein was purified from cultured Patu8988 cells using the Phosphoprotein Purification Kit. Cell apoptosis was detected using propidium iodide–Annexin V staining to investigate the relation between the expression of B7-H3 and Patu8988 cells treated with gemcitabine. Western blot was used to determine the effect of B7-H3 on the expression of proteins including extracellular signal–regulated kinase (ERK)1/2, epidermal growth factor receptor (EGFR), and Inhibitor of NF-κB(IκB) in Patu8988 cells; B7-H3 was activated by 4H7, which as an agonist monoclonal antibody to B7-H3.

Results

The expression of B7-H3 was found to be higher in tumor tissues than in normal tissues of pancreatic carcinoma. Survival analysis revealed that patients in the low-B7-H3 expression group were likely to have a longer overall survival compared with those in the high-expression group (P < 0.05). B7-H3 activated by 4H7 could reduce gemcitabine-induced apoptosis in Patu8988 cells. Activation of B7-H3 by 4H7 induced variations in p-ERK1/2, EGFR, and IκB protein levels. When B7-H3 was upregulated, the expression levels of EGFR and p-ERK1/2 proteins significantly increased (P < 0.05), but the expression level of IκB significantly decreased (P < 0.05), especially in the gemcitabine-treated group.

Conclusion

This study demonstrated that B7-H3 could deliver signals to pancreatic cancer cells to combat apoptosis induced by gemcitabine.