APC alterations are frequently involved in the pathogenesis of acinar cell carcinoma of the pancreas, mainly through gene loss and promoter hypermethylation

A narrative review on rare types of pancreatic cancer: should they be treated as pancreatic ductal adenocarcinomas?

Pancreatic cancer is one of the deadliest malignancies in humans and it is expected to play a bigger part in cancer burden in the years to come. Pancreatic ductal adenocarcinoma (PDAC) represents 85% of all primary pancreatic malignancies. Recently, much attention has been given to PDAC, with significant advances in the understanding of the mechanisms underpinning disease initiation and progression, along with noticeable improvements in overall survival in both localized and metastatic settings. However, given their rarity, rare histological subtypes of pancreatic cancer have been underappreciated and are frequently treated as PDAC, even though they might present non-overlapping molecular alterations and clinical behavior. While some of these rare histological subtypes are true variants of PDAC that should be treated likewise, others represent separate clinicopathological entities, warranting a different therapeutic approach. In this review, we highlight clinical, pathological, and molecular aspects of rare histological types of pancreatic cancer, along with the currently available data to guide treatment decisions.

Exceptional Response of BRAFV600E-Mutated Acinar Cell CUP to BRAF/MEK Inhibition

Complete remission of BRAF V600E-driven ACC CUP by BRAF/MEK inhibition underscores importance of precision oncology.

Solid pseudopapillary neoplasms of the pancreas in childhood and adolescence-an analysis of the German Registry for Rare Pediatric Tumors (STEP)

Solid pseudopapillary neoplasms (SPNs) are the most common entity among pediatric pancreatic tumors. Still, these are rare tumors with an annual incidence of 0.1-0.2/1,000,000, and little is known about their optimal treatment. This analysis aimed to increase knowledge about the occurrence and treatment strategies of SPN in childhood. Data regarding diagnostics, treatment, and outcome of children aged 0-18 years with SPN recorded in the German Registry for Rare Pediatric Tumors (STEP) were analyzed. Thirty-eight patients were identified with a median age of 14.5 years at diagnosis (range: 8-18) and a female preponderance (81.6%). The most frequent location of the tumor was the pancreatic tail. In histopathological and immunohistochemical examination, pseudopapillary, solid, and cystic lesions as well as expression of beta-catenin, progesterone receptors, and cyclin D1 were the most common findings. All patients underwent surgical resection. Most patients underwent open resection, predominantly tail resection for tumors in the tail region and pylorus-preserving pancreaticoduodenectomy for tumors in the head region. The main postoperative sequela was exogenous pancreatic insufficiency (23.7%), especially with SPN in the pancreatic head. No recurrence occurred during follow-up, although two patients underwent resection with microscopic residue.

CONCLUSION

SPN of the pancreas in childhood are low-grade malignancies with usually favorable treatment outcomes. However, therapy can lead to relevant long-term sequelae. To prevent recurrence, complete surgical resection is recommended, sparing as much healthy pancreatic tissue as possible. Interdisciplinary collaboration between specialists is essential to optimize treatment. Molecular genetic analysis of these tumors could improve understanding of their genesis.

WHAT IS KNOWN

• Solid pseudopapillary neoplasms (SPNs) of the pancreas are very rare tumors in childhood. • Little is known about tumorigenesis, and there are no specific guidelines for treatment and follow-up in pediatric patients.

WHAT IS NEW

• Characteristics, treatment, and outcome were comprehensively assessed in a large cohort of pediatric patients with SPN. • We propose recommendations for diagnosis, treatment, and follow-up of children with SPN, based on our analysis and considering published experience.

Molecular features of pancreaticobiliary neoplasms: Implications for diagnosis, prognostication, and therapy selection

BACKGROUND

Molecular diagnostics has impacted the diagnosis, prediction of prognosis, and selection of targeted therapy for many tumor types. While pulmonary adenocarcinomas and melanomas are among the neoplasms most associated with molecular diagnostics and targeted therapy, malignancies of the pancreaticobiliary system have also been impacted by precision medicine.

METHODS

We undertook an electronic search using PubMed and Embase to review the published literature to determine what forms of molecular testing, mutations and oncogenetic pathways are associated with neoplasms of the pancreaticobiliary system. Keywords utilized were pancreas, bile duct, mutations, ERCP, FNA, KRAS, SMAD4, TP53, next-generation sequencing, serous cystadenoma, pancreatic ductal adenocarcinoma, intraductal papillary mucinous neoplasm, cystic mucinous neoplasm, solid pseudo-papillary neoplasm.

RESULTS

A search between 1999 and 2022 yielded 6874 manuscripts. Screening of these yielded 302 more focused manuscripts of which 55 were used for the study. Ductal adenocarcinoma of the pancreas is associated with a progression of mutations beginning wit KRAS mutations and ending with a set of mutations in the TP53, SMAD4, and DPC4 genes. Similar mutations are found in neoplastic mucinous cysts. Specific mutations characterize serous cystadenomas, solid, and pseudo papillary neoplasms and adenocarcinomas of the bile ducts.

CONCLUSIONS

Mutational analysis of cytologic specimens obtained by fine-needle aspiration, and duct brushings and washings are helpful in the diagnosis of pancreaticobiliary neoplasms and may supply prognostic information.

Refined pancreatobiliary UroVysion criteria and an approach for further optimization

Pancreatobiliary strictures are a common source of false negatives for malignancy detection. UroVysion is more sensitive than any other method but remains underutilized because of conflicting sensitivities and specificities due to a lack of standardized cutoff criteria and confusion in interpreting results in the context of primary sclerosing cholangitis. We set out to determine the sensitivities and specificities of UroVysion, brushing cytology, forceps biopsies, and fine needle aspiration (FNAs) for pancreatobiliary stricture malignancy detection. A retrospective review was performed of all biopsied pancreatobiliary strictures at our institution over 5 years. UroVysion was unquestionably the most sensitive method and all methods were highly specific. Sensitivity was highest while maintaining specificity when a malignant interpretation was limited to cases with 5+ cells with the same polysomic signal pattern and/or loss of one or both 9p21 signals. Only UroVysion detected the metastases and a neuroendocrine tumor. In reviewing and analyzing the signal patterns, we noticed trends according to location and diagnosis. Herein we describe our method for analyzing signal patterns and propose cutoff criteria based upon observations gleaned from such analysis.

[Rare pancreatic tumors]

Beyond pancreatic ductal adenocarcinoma, which is by far the most frequent pancreatic neoplasm, a great variety of tumors occur in the pancreas. They include solid and cystic masses and epithelial and nonepithelial neoplasms, and they show a great diversity in their biological behavior, ranging from benign tumors to highly aggressive neoplasms. As examples of rare pancreatic tumors, clinical, morphological, and molecular aspects of acinar cell carcinoma, pancreatoblastoma, solid pseudopapillary neoplasm, and serous cystic neoplasms are presented and discussed.

Exome Sequencing of Pancreatic Acinar Carcinoma Identified Distinctive Mutation Patterns

OBJECTIVES

Pancreatic acinar cell carcinoma (ACC) is a rare pancreatic cancer. The advancement of treatment is hampered because of the limited knowledge of its molecular mechanism.

METHODS

Whole-exome sequencing was performed on DNA extracted from 11 pure ACC surgical samples. Potential germline variants were removed on the basis of polymorphic databases, alternative allele frequency, coverage depth, and Catalogue of Somatic Mutations in Cancer (COSMIC) annotations after variant calling procedure. Mutation profiles and signatures were assessed through the Mutational Patterns package.

RESULTS

A median of 34 somatic mutations were detected (range, 19-60). Three novel recurrent small deletions were identified. Common pancreatic ductal adenocarcinoma mutations or neuroendocrine tumor mutants were not found. FAT atypical cadherin 4, mucin 5B, titin, and zinc finger homeobox 3 were consistently mutated across 4 independent ACC studies. A high contribution of COSMIC mutational signature 1 was seen in ACC, indicating deamination of 5-methylcytosine. The majority of the patients had COSMIC signatures 6, 15, or 20, relating to defective DNA mismatch repair. Six patients showed COSMIC mutational signature 10 because of the altered activity of DNA polymerase epsilon.

CONCLUSIONS

Distinct mutational signatures pathways were found in ACC and targeting them may improve clinical outcome.

Targeting the NTRK Fusion Gene in Pancreatic Acinar Cell Carcinoma: A Case Report and Review of the Literature

Pancreatic acinar cell carcinoma (PACC) is a rare pancreatic exocrine malignancy. Compared with the more common pancreatic ductal adenocarcinoma (PDAC), PACC is more common in younger White men, has earlier stages and a lower mean age (56 vs 70 years) at the time of presentation, and has a better prognosis. In addition to differences in demographic, histologic, and clinical characteristics, PACC has a genomic profile distinct from PDAC, with only rare mutations in TP53, KRAS, and p16 that are commonly found in PDAC. This case report presents a man aged 81 years who presented with a pancreatic body mass with peripancreatic lymph node enlargement. Biopsy of the mass showed acinar cell carcinoma. The patient underwent upfront surgical resection, followed by one cycle of adjuvant gemcitabine, with stoppage of therapy due to poor tolerance. Lower-dose gemcitabine was reintroduced after disease progression 6 months later. Nab-paclitaxel was added to gemcitabine after 6 cycles because of a continued increase in the size of peripancreatic lymph nodes. Combination chemotherapy was stopped after 4 cycles because of further disease progression with new liver metastasis. Molecular testing showed the presence of an SEL1L-NTRK1 fusion. Targeted therapy was started with the oral neurotrophic tropomyosin receptor kinase (NTRK) inhibitor larotrectinib at a dosage of 100 mg twice daily. At the time of writing, the patient has been on therapy for 13 months with an exceptional radiographic response and has not experienced any grade 3 adverse effects. To our knowledge, this is the first clinical report of an NTRK gene fusion in a patient with PACC. This case study highlights the significance of tumor molecular profiling in patients with pancreatic tumors, especially rare histologies.

Multicenter Retrospective Analysis of Chemotherapy for Advanced Pancreatic Acinar Cell Carcinoma: Potential Efficacy of Platinum- and Irinotecan-Containing Regimens

OBJECTIVES

The aim of this multicenter retrospective study was to identify the optimal chemotherapeutic regimen for advanced pancreatic acinar cell carcinoma (PACC).

METHODS

Fifty-eight patients with histopathologically confirmed advanced PACC who had received chemotherapy between 1996 and 2013 were enrolled. The clinical characteristics of the patients and the treatment efficacy data were collected from the medical records at 16 Japanese institutions, using standardized data collection instrument.

RESULTS

The most commonly selected treatment regimens were gemcitabine-, fluoropyrimidine-, platinum-, and irinotecan-containing regimens. The overall response rate in the patients who received first-line chemotherapy were 7% and 38%, respectively, and the median overall survival was 13.2 months. When the data for all the treatment lines were aggregated, the response rates to gemcitabine-, fluoropyrimidine-, platinum-, and irinotecan-containing regimens were 7%, 18%, 40%, and 29%, respectively. The overall survival tended to be better in patients who had received a platinum-containing regimen (hazard ratio, 0.50; 95% confidence interval, 0.23-1.11; P = 0.08) or irinotecan-containing regimen (hazard ratio, 0.42; 95% confidence interval, 0.15-1.19; P = 0.09) at least once in the treatment course as compared with those who had not.

CONCLUSIONS

Our findings suggested that platinum- and irinotecan-containing regimens exhibited some potential efficacy in patients with advanced PACC.

Looking into digestive mixed neuroendocrine - nonneuroendocrine neoplasms: subtypes, prognosis, and predictive factors

Mixed neuroendocrine - nonneuroendocrine neoplasms (MiNENs) of the digestive system represent a challenge for both pathologists and clinicians. Their nomenclature has changed several times, and their diagnostic criteria, classification and clinical behaviour have been matter of debate over the years. Although several attempts have been made to elucidate the pathogenesis and biology of MiNENs, some issues remain open. This review will provide: a historical background that helps in understanding the evolution of the concept and nomenclature of mixed neoplasms; a revision of the knowledge on this topic, including molecular aspects, to give the reader a comprehensive and practical overview on this challenging field of pathology; a focus on the diagnostic criteria and on the determination of prognostic and predictive factors; and a description of the different tumour types in the different sites of origin.

Malignant epithelial/exocrine tumors of the pancreas

Pancreatic malignant exocrine tumors represent the most important cause of cancer-related death for pancreatic neoplasms. The most common tumor type in this category is represented by pancreatic ductal adenocarcinoma (PDAC), an ill defined, stroma-rich, scirrhous neoplasm with glandular differentiation. Here we present the relevant characteristics of the most important PDAC variants, namely adenosquamous carcinoma, colloid carcinoma, undifferentiated carcinoma, undifferentiated carcinoma with osteoclast-like giant cells, signet ring carcinoma, medullary carcinoma and hepatoid carcinoma. The other categories of malignant exocrine tumors, characterized by fleshy, stroma-poor, circumscribed neoplasms, include acinar cell carcinoma (pure and mixed), pancreatoblastoma, and solid pseudopapillary neoplasms. The most important macroscopic, histologic, immunohistochemical and molecular hallmarks of all these tumors, highlighting their key diagnostic/pathological features are presented. Lastly, standardized indications regarding gross sampling and how to compile a formal pathology report for pancreatic malignant exocrine tumors will be provided.

Successful BRAF/MEK inhibition in a patient with BRAF V600E-mutated extrapancreatic acinar cell carcinoma

Pancreatic acinar cell carcinoma (PAC) is a rare disease with a poor prognosis. Treatment options for metastatic PAC are limited and often follow chemotherapeutic regimens for pancreatic ductal adenocarcinoma. Although recurrent genomic alterations, such as BRAF fusions and defects in genes involved in homologous recombination DNA repair, have been described in PAC, data on the clinical efficacy of molecularly guided, targeted treatment are scarce. Here we describe the case of a 27-yr-old patient with BRAF^V600E-mutated PAC who was successfully treated with a combination of BRAF and MEK inhibitors. The patient presented to our clinic with abdominal pain and weight loss. Imaging showed extensive retroperitoneal disease as well as mediastinal lymphadenopathy. Because of elevated α-fetoprotein (AFP) levels and inconclusive histologic findings, a germ cell tumor was suspected; however, PEI chemotherapy was unsuccessful. A repeat biopsy yielded the diagnosis of PAC and treatment with FOLFIRINOX was initiated. Comprehensive molecular profiling within the MASTER (Molecularly Aided Stratification for Tumor Eradication Research) precision oncology program revealed a somatic BRAF^V600E mutation and a germline PALB2 stop-gain mutation. Therapy was therefore switched to BRAF/MEK inhibition, resulting in almost complete remission and disease control for 12 mo and a remarkable improvement in the patient's general condition. These results indicate that BRAF alterations are a valid therapeutic target in PAC that should be routinely assessed in this patient population.

Long-term survival of two patients with recurrent pancreatic acinar cell carcinoma treated with radiofrequency ablation: A case report

BACKGROUND

Pancreatic acinar cell carcinoma (PACC) is a rare type of malignant pancreatic cancer that represents approximately 1% of all pancreatic neoplasms. Due to its very low incidence, only a few retrospective studies are available. Although surgery is the first choice for treatment, most patients experience recurrence (mainly in the liver) and there are no clear recommendations for patients with advanced disease.

CASE SUMMARY

We report two patients with PACC treated with surgery who experienced tumour recurrence in the liver. Patient 1 carried a germline mutation in the APC gene. Both patients were treated with gemcitabine plus oxaliplatin and gemcitabine plus capecitabine as first- and second-line therapies, respectively. After a favourable response to chemotherapy, the patients underwent radiofrequency ablation of the remaining liver metastases. For patient 1, we documented a relapse in the liver after a disease-free period of 9 mo, and treatment with gemcitabine plus capecitabine was restarted. The patient achieved a complete response, and he remains alive without evidence of disease recurrence after six years. After radiofrequency ablation, patient 2 experienced disease-free survival for 21 mo, when peritoneal relapse was diagnosed and treated with chemotherapy. The patient achieved a stable disease state for nearly two years; nevertheless, further progressive disease was documented, and he died seven years after the first relapse.

CONCLUSION

PACC presents different biological behaviours than pancreatic adenocarcinoma. Multidisciplinary treatment involving local ablative therapies may be considered for PACC.

RAS in pancreatic cancer

The pancreas is a gland composed mainly by endocrine and exocrine cells, giving rise to three main tumour types. Pancreatic neuroendocrine tumour or PNET arise from the endocrine portion of the pancreas. On the contrary, pancreatic exocrine neoplasms include pancreatic ductal adenocarcinoma (PDAC) and acinar cell carcinoma. PDAC is the most common type of pancreatic cancer and one of the leading causes of cancer-related death. It has been shown that less than 3% of PDAC patients have an overall survival of up to 5 years in the U.K. This mainly arises since the majority of patients diagnosed with PDAC present with advanced unresectable disease, which is highly resistant to all forms of chemotherapy and radiotherapy. Activating mutations of an isoform of the RAS protein, KRAS, are found in almost all PDAC cases and occur during early stages of malignant transformation. KRAS mutations play a critical role as they are involved in both initiating and maintaining PDAC development. The interaction of RAS with GDP/GTP along with its recruitment to the membrane affects transduction of its activating signals to downstream effectors. In this review, we aim to summarise different mutations of RAS and their prevalence in pancreatic cancer along with other RAS-induced tumours. In addition, we briefly discuss the genetically engineered mouse models that have been developed to study KRAS-mutated adenocarcinomas in the pancreas. These provide an opportunity to also address the importance of targeting RAS for better treatment response in PDAC patients along with the challenges incurred herein.

Acinar cell carcinoma of the pancreas with thyroid-like follicular features: first description of a new diagnostic challenging subtype

Acinar cell carcinomas (ACCs) of the pancreas are a heterogeneous group of neoplasms showing a wide spectrum of morphological features including acinar, solid, glandular, and trabecular architecture. In addition, uncommon cytological aspects have recently been described and include oncocytic, spindle, clear, and pleomorphic cell types. This wide histological spectrum represents a challenge in the diagnostic task for pathologists. Molecular mechanisms involved in the onset and progression of ACCs are not completely known, but, in general, they differ from those observed in ductal adenocarcinomas or neuroendocrine neoplasms of the pancreas and frequently include alterations in the APC/β-catenin pathway. In the present paper, we describe a new variant of ACC showing thyroid-like follicular features and CTNNB1 mutation. This phenotype needs to be included in the spectrum of morphological presentation of ACC.

Ancillary Techniques in Cytologic Specimens Obtained from Solid Lesions of the Pancreas: A Review

Advanced methods of molecular characterization have elucidated the genetic, epigenetic, and proteomic alterations associated with the broad spectrum of pancreatic disease, particularly neoplasia. Next-generation sequencing, in particular, has revealed the genomic diversity among pancreatic ductal adenocarcinoma, neuroendocrine and acinar tumors, solid pseudopapillary neoplasm, and other pancreatico-biliary neoplasms. Differentiating these entities from one another by morphologic analysis alone may be challenging, especially when examining the small quantities of diagnostic material inherent to cytologic specimens. In order to enhance the sensitivity and specificity of pancreatic cytomorphology, multiple diagnostic, prognostic, and predictive ancillary tests have been and continue to be developed. Although a great number of such tests have been developed for evaluation of specimens collected from cystic lesions and strictures, ancillary techniques also play a significant role in the evaluation of cytologic specimens obtained from solid lesions of the pancreas. Furthermore, while some tests have been developed to differentiate diagnostic entities from one another, others have been developed to simply identify dysplasia and malignancy. Ancillary studies are particularly important in the subset of cases for which cytomorphologic analysis provides a result that is equivocal or insufficient to guide clinical management. Selection of appropriate ancillary testing modalities requires familiarity with both their methodology and the molecular basis of the pancreatic diseases for which testing is being performed.

Molecular Diagnostics in the Neoplasms of the Pancreas, Liver, Gallbladder, and Extrahepatic Biliary Tract: 2018 Update

Pancreatic neoplasms, including ductal adenocarcinoma, solid pseudopapillary neoplasm, pancreatic endocrine neoplasms, acinar cell carcinoma, and pancreatoblastoma, are associated with different genetic abnormalities. Hepatic adenomas with beta-catenin exon 3 mutation are associated with a high risk of malignancy. Hepatic adenoma with arginosuccinate synthetase 1 expression or sonic hedgehog mutations are associated with a risk of bleeding. Hepatocellular carcinoma and choangiocarcinoma display heterogeneity at both morphologic and molecular levels Cholangiocellular carcinoma is most commonly associated with IDH 1/2 mutations.

Liver and Pancreas: Do Similar Embryonic Development and Tissue Organization Lead to Similar Mechanisms of Tumorigenesis?

The liver and pancreas are closely associated organs that share a common embryological origin. They display amphicrine properties and have similar exocrine organization with parenchymal cells, namely, hepatocytes and acinar cells, secreting bile and pancreatic juice into the duodenum via a converging network of bile ducts and pancreatic ducts. Here we compare and highlight the similarities of molecular mechanisms leading to liver and pancreatic cancer development. We suggest that unraveling tumor development in an organ may provide insight into our understanding of carcinogenesis in the other organ.

c-MYC amplification and c-myc protein expression in pancreatic acinar cell carcinomas. New insights into the molecular signature of these rare cancers

The molecular alterations of pancreatic acinar cell carcinomas (ACCs) and mixed acinar-neuroendocrine carcinomas (MANECs) are not completely understood, and the possible role of c-MYC amplification in tumor development, progression, and prognosis is not known. We have investigated c-MYC gene amplification in a series of 35 ACCs and 4 MANECs to evaluate its frequency and a possible prognostic role. Gene amplification was investigated using interphasic fluorescence in situ hybridization analysis simultaneously hybridizing c-MYC and the centromere of chromosome 8 probes. Protein expression was immunohistochemically investigated using a specific monoclonal anti-c-myc antibody. Twenty cases had clones with different polysomies of chromosome 8 in absence of c-MYC amplification, and 5 cases had one amplified clone and other clones with chromosome 8 polysomy, while the remaining 14 cases were diploid for chromosome 8 and lacked c-MYC amplification. All MANECs showed c-MYC amplification and/or polysomy which were observed in 54% pure ACCs. Six cases (15.3%) showed nuclear immunoreactivity for c-myc, but only 4/39 cases showed simultaneous c-MYC amplification/polysomy and nuclear protein expression. c-myc immunoreactivity as well as c-MYC amplification and/or chromosome 8 polysomy was not statistically associated with prognosis. Our study demonstrates that a subset of ACCs shows c-MYC alterations including gene amplification and chromosome 8 polysomy. Although they are not associated with a different prognostic signature, the fact that these alterations are present in all MANECs suggests a role in the acinar-neuroendocrine differentiation possibly involved in the pathogenesis of MANECs.

Case report: primary acinar cell carcinoma of the liver treated with multimodality therapy

We describe a case of primary acinar cell carcinoma (ACC) originating in the liver in a 54-year-old female, diagnosed following persistent abnormal elevated liver function. Imaging revealed two masses, one dominant lesion in the right hepatic lobe and another in segment IVA. A right hepatectomy was performed to remove the larger lesion, while the mass in segment IVA was unresectable due to its proximity to the left hepatic vein. Immunohistochemical staining showed positivity for trypsin and chymotrypsin. Postoperatively the patient underwent hepatic arterial embolization of the other unresectable lesion followed by FOLFOX chemotherapy. At 20 months from diagnosis the patient is currently under observation with a decreasing necrotic mass and no other disease evident. Based on histology, immunohistochemistry and radiological findings a diagnosis of primary ACC of the liver was made. Genomic assessment of somatic mutations within the patient's tumor was also performed through next generation sequencing and findings were consistent with an acinar malignancy. This case highlights a rare tumor subtype treated with a combination of therapeutic modalities through a multidisciplinary approach.

Pancreatic Cancer: Molecular Characterization, Clonal Evolution and Cancer Stem Cells

Pancreatic Ductal Adenocarcinoma (PDAC) is the fourth most common cause of cancer-related death and is the most lethal of common malignancies with a five-year survival rate of <10%. PDAC arises from different types of non-invasive precursor lesions: intraductal papillary mucinous neoplasms, mucinous cystic neoplasms and pancreatic intraepithelial neoplasia. The genetic landscape of PDAC is characterized by the presence of four frequently-mutated genes: KRAS, CDKN2A, TP53 and SMAD4. The development of mouse models of PDAC has greatly contributed to the understanding of the molecular and cellular mechanisms through which driver genes contribute to pancreatic cancer development. Particularly, oncogenic KRAS-driven genetically-engineered mouse models that phenotypically and genetically recapitulate human pancreatic cancer have clarified the mechanisms through which various mutated genes act in neoplasia induction and progression and have led to identifying the possible cellular origin of these neoplasias. Patient-derived xenografts are increasingly used for preclinical studies and for the development of personalized medicine strategies. The studies of the purification and characterization of pancreatic cancer stem cells have suggested that a minority cell population is responsible for initiation and maintenance of pancreatic adenocarcinomas. The study of these cells could contribute to the identification and clinical development of more efficacious drug treatments.

Genome-wide genetic and epigenetic analyses of pancreatic acinar cell carcinomas reveal aberrations in genome stability

Pancreatic acinar cell carcinoma (ACC) is an aggressive exocrine tumor with largely unknown biology. Here, to identify potential targets for personalized treatment, we perform integrative genome-wide and epigenome-wide analyses. The results show frequently aberrant DNA methylation, abundant chromosomal amplifications and deletions, and mutational signatures suggesting defective DNA repair. In contrast to pancreatic ductal adenocarcinoma, no recurrent point mutations are detected. The tumor suppressors ID3, ARID1A, APC, and CDKN2A are frequently impaired also on the protein level and thus potentially affect ACC tumorigenesis. Consequently, this work identifies promising therapeutic targets in ACC for drugs recently approved for precision cancer therapy.

Clinical outcomes of patients with resectable pancreatic acinar cell carcinoma

OBJECTIVE

Given the rarity of the disease, the post-resection clinical course of localized pancreatic acinar cell carcinoma (ACC) is largely unknown. Therefore, we aimed to analyze the outcomes of patients with localized pancreatic ACC who underwent curative surgical resection.

METHODS

We retrospectively analyzed the outcomes of 20 patients with resectable pancreatic ACC who underwent surgery.

RESULTS

Altogether 20 patients were included in the study, with a median age of 57 years and a male predominance. There were eight pure ACC, 10 mixed acinar-neuroendocrine carcinomas and two mixed acinar-ductal adenocarcinomas. Among the 15 patients who were staged histologically, 3, 8 and 4 were at stages IB, IIA and IIB, respectively. Eleven patients received adjuvant chemotherapy (5-fluorouracil-based [n = 9]; gemcitabine [n = 1]; etoposide plus cisplatin [n = 1]). In a median follow-up period of 27.1 months, disease recurred in 10 patients, most commonly in the liver (90%). Median recurrence-free survival and overall survival were 16.9 months and 75.0 months, respectively. Elevation of cancer antigen 19-9 (CA19-9), lymph node metastasis and neural invasion were significantly associated with poor overall survival (P = 0.007, P = 0.027 and P = 0.016, respectively).

CONCLUSIONS

Compared with ductal adenocarcinoma, resectable pancreatic ACC has a favorable prognosis after surgery. Considering that distant metastasis is the most common pattern of recurrence, further studies are necessary to define the role of adjuvant chemotherapy for improving survival outcomes.

Systematic Review and Case Series Report of Acinar Cell Carcinoma of the Pancreas

BACKGROUND

Acinar cell carcinoma of the pancreas is a rare malignancy representing less than 1% of all pancreatic malignancies.

METHODS

We report on a case series of 21 patients with acinar cell carcinoma of the pancreas treated at a high-volume quaternary center. A systematic review of the medical literature was performed that described typical therapeutic management approaches for acinar cell carcinoma of the pancreas and reported on disease control and survival rates. Data for the case series were obtained from a prospective database.

RESULTS

In our systematic review of 6 articles, study patients had a median age of 61 years, 66% were male, 52% had stage I/II disease, and 55% of lesions were located in the pancreatic head. The rates of median survival were approximately 47 months after resection with adjuvant therapy, 38 months for nonmetastatic, locally unresectable disease, and 17 months for metastatic disease treated with chemotherapy. Combination fluoropyrimidine-based chemotherapy regimens had better rates of disease control than other therapies. Our case series included 21 study patients, 14 of whom required resection and 7 who had metastatic disease. The rates of median survival were 40.2 ± 31.9 months in those who underwent surgery and were treated with adjuvant therapy and 13.8 ± 11.3 months for patients with metastatic disease.

CONCLUSIONS

Multidisciplinary treatment for acinar cell carcinoma of the pancreas should be considered due to the rarity of the disease and its lack of high-level therapeutic data. Progress in the molecular analysis of this tumor may improve outcomes through the use of personalized therapy based on underlying tumor mutations.

The Evolving Role of Pathology in New Developments, Classification, Terminology, and Diagnosis of Pancreatobiliary Neoplasms

Pancreatobiliary tract lesions are increasingly being discovered because of more sensitive imaging modalities. Magnetic resonance imaging has identified incidental pancreatic cysts in 13.5% of patients of progressively increasing age. Pancreatobiliary tissue is more accessible through endoscopic ultrasound and magnetic resonance imaging-guided biopsy procedures, and is now an integral part of pathologists' routine practice. Accordingly, several new tumor categories have been recently recognized, including intraductal tubulopapillary neoplasm, a new addition to tumoral intraepithelial neoplasms. Other entities have been reclassified, including the recent transition to 2-tiered grading of preinvasive neoplasms, as well as new perspectives on the distinctive biologic behavior of oncocytic intraductal papillary mucinous neoplasms (IPMNs) compared with other IPMN subtypes. This has led to proposals for revised staging of virtually every segment of the pancreatobiliary tree, with theranostic markers becoming an integral part of workup. Ki-67 is now an integral part of the classification of neuroendocrine tumors, with new definitions of "high-grade neuroendocrine carcinoma." Although bile duct brushings have opened new avenues for diagnosis, their sensitivity remains low and often requires concomitant fluorescent in situ hybridization to better define ambiguous cases. Various molecular pathways have been elucidated for pancreatic cysts, including KRAS for ductal neoplasia, GNAS for intestinal IPMNs, RNF3 for mucinous cysts, and VHL for serous cystic neoplasms, all key players in diagnostic workup. Integration of these updates into our understanding of pancreatobiliary disease requires active engagement of pathologists for appropriate specimen triage, judicious interpretation of results, and incorporation into reporting and staging. They also provide exciting opportunities for targeted therapy.

Regulatory single nucleotide polymorphisms (rSNPs) at the promoters 1A and 1B of the human APC gene

Background

Germline mutations in the coding sequence of the tumour suppressor APC gene give rise to familial adenomatous polyposis (which leads to colorectal cancer) and are associated with many other oncopathologies. The loss of APC function because of deletion of putative promoter 1A or 1B also results in the development of colorectal cancer. Since the regions of promoters 1A and 1B contain many single nucleotide polymorphisms (SNPs), the aim of this study was to perform functional analysis of some of these SNPs by means of an electrophoretic mobility shift assay (EMSA) and a luciferase reporter assay.

Results

First, it was shown that both putative promoters of APC (1A and 1B) drive transcription in an in vitro reporter experiment. From eleven randomly selected SNPs of promoter 1A and four SNPs of promoter 1B, nine and two respectively showed differential patterns of binding of nuclear proteins to oligonucleotide probes corresponding to alternative alleles. The luciferase reporter assay showed that among the six SNPs tested, the rs75612255 C allele and rs113017087 C allele in promoter 1A as well as the rs138386816 T allele and rs115658307 T allele in promoter 1B significantly increased luciferase activity in the human erythromyeloblastoid leukaemia cell line K562. In human colorectal cancer HCT-116 cells, none of the substitutions under study had any effect, with the exception of minor allele G of rs79896135 in promoter 1B. This allele significantly decreased the luciferase reporter’s activity

Conclusion

Our results indicate that many SNPs in APC promoters 1A and 1B are functionally relevant and that allele G of rs79896135 may be associated with the predisposition to colorectal cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12863-016-0460-8) contains supplementary material, which is available to authorized users.

Efficacy of Chemotherapy in Patients with Unresectable or Metastatic Pancreatic Acinar Cell Carcinoma: Potentially Improved Efficacy with Oxaliplatin-Containing Regimen

Purpose

Pancreatic acinar cell carcinoma (ACC) is a rare cancer of the exocrine pancreas. Because of its rare incidence, the efficacy of chemotherapy in this patient population has been largely unknown. Therefore, we retrospectively analyzed the outcomes of patients with advanced pancreatic ACC who received chemotherapy.

Materials and Methods

Between January 1997 and March 2015, 15 patients with unresectable or metastatic pancreatic ACC who received systemic chemotherapy were identified in Asan Medical Center, Korea.

Results

The median age was 58 years. Eleven and four patients had recurrent/metastatic and locally advanced unresectable disease. The median overall survival in all patients was 20.9 months (95% confidence interval [CI], 15.7 to 26.1). As first-line therapy, intravenous 5-fluorouracil were administered in four patients (27%), gemcitabine in five (33%), gemcitabine plus capecitabine in two (13%), oxaliplatin plus 5-fluorouracil/leucovorin (FOLFOX) in two (13%), and concurrent chemoradiotherapy followed by capecitabine maintenance therapy in two (13%). The objective response rate (ORR) to chemotherapy alone was 23% and the median progression-free survival (PFS) was 5.6 months (95% CI, 2.8 to 8.4). After progression, second-line chemotherapy was administered in eight patients, while four patients received FOLFOX and the other four patients received gemcitabine. The ORR was 38%, and patients administered FOLFOX had significantly better PFS than those administered gemcitabine (median, 6.5 months vs. 1.4 months; p=0.007). The ratio of time to tumor progression (TTP) during first-line chemotherapy to TTP at second-line chemotherapy was significantly higher in patients administered FOLFOX (4.07; range, 0.87 to 8.30) than in those administered gemcitabine (0.12; range, 0.08 to 0.25; p=0.029).

Conclusion

Our results suggest that oxaliplatin-containing regimens may have improved activity against pancreatic ACC.

Nonductal Pancreatic Cancers

Nonductal pancreatic neoplasms, including solid pseudopapillary neoplasms, acinar cell carcinomas, and pancreatoblastomas, are uncommon. These entities share overlapping gross, microscopic, and immunohistochemical features, such as well-demarcated solid neoplasms, monotonous cellular tumor cells with little intervening stroma, and abnormal beta-catenin expression. Each tumor also has unique clinicopathologic characteristics with diverse clinical behavior. To differentiate nonductal pancreatic neoplasms, identification of histologic findings, such as pseudopapillae, acinar cell features, and squamoid corpuscles, is important. Immunostainings for acinar cell or neuroendocrine markers are helpful for differential diagnosis. This article describes the clinicopathologic and immunohistochemical features of nonductal pancreatic cancers.

Molecular Genetics of Pancreatic Neoplasms

Pancreatic neoplasms have a wide range of histologic types with distinct clinical outcomes. Recent advances in high-throughput sequencing technologies have greatly deepened our understanding of pancreatic neoplasms. Now, the exomes of major histologic types of pancreatic neoplasms have been sequenced, and their genetic landscapes have been revealed. This article reviews the molecular changes underlying pancreatic neoplasms, with a special focus on the genetic changes that characterize the histologic types of pancreatic neoplasms. Emphasis is also made on the molecular features of key genes that have the potential for therapeutic targets.

p53 and p16Ink4a/p19Arf Loss Promotes Different Pancreatic Tumor Types from PyMT-Expressing Progenitor Cells

In human studies and mouse models, the contributions of p53 and p16^Ink4a/p19^Arf loss are well established in pancreatic ductal adenocarcinoma (PDAC). Although loss of functional p53 pathway and loss of Ink4a/Arf in human pancreatic acinar cell carcinoma (PACC) and pancreatic neuroendocrine tumor (PanNET) are identified, their direct roles in tumorigenesis of PACC and PanNET remain to be determined. Using transgenic mouse models expressing the viral oncogene polyoma middle T antigen (PyMT), we demonstrate that p53 loss in pancreatic Pdx1+ progenitor cells results in aggressive PACC, whereas Ink4a/Arf loss results in PanNETs. Concurrent loss of p53 and Ink4a/Arf resembles loss of p53 alone, suggesting that Ink4a/Arf loss has no additive effect to PACC progression. Our results show that specific tumor suppressor genotypes provocatively influence the tumor biological phenotypes in pancreatic progenitor cells. Additionally, in a mouse model of β-cell hyperplasia, we demonstrate that p53 and Ink4a/Arf play cooperative roles in constraining the progression of PanNETs.

A comparison study of pancreatic acinar cell carcinoma with ductal adenocarcinoma using computed tomography in Chinese patients

Pancreatic acinar cell carcinoma (ACC) is a rare tumor that is difficult to diagnose preoperatively. The aim of this study was to evaluate and describe the computed tomography (CT) features of ACC and compare the results with pancreatic ductal adenocarcinoma (DAC) for improving preoperative diagnosis. The control group consisted of 34 patients with DAC collected from the pathology electronic database. The CT imaging from nine patients with pathologically confirmed ACC was retrospectively reviewed. Two radiologists independently assessed the tumor location, size, texture, and enhancement patterns. We found that 64.3% (9/14) of ACC tumors were homogeneous and 35.7% (5/14) had necrosis. The percentage of common bile duct and pancreatic ductal dilation was 14.3% (2/14) and 7.1% (1/14), respectively. The mean size of ACC was 50.1±24.2 mm. The mean attenuation of ACC was 35.4±3.9 Hounsfield unit (HU) before enhancement, 73.1±42.9 HU in arterial phase, and 71.8±15.6 HU in port venous phase. It is difficult to distinguish ACC from DAC preoperatively only based on CT findings. However, compared with DAC, we found that ACC tumors are likely to be larger and contain more heterogeneous intratumoral necrotic hypovascular regions, and less pancreatic ductal and common biliary dilation.

Surgical and molecular pathology of pancreatic neoplasms

BACKGROUND

Histologic characteristics have proven to be very useful for classifying different types of tumors of the pancreas. As a result, the major tumor types in the pancreas have long been classified based on their microscopic appearance.

MAIN BODY

Recent advances in whole exome sequencing, gene expression profiling, and knowledge of tumorigenic pathways have deepened our understanding of the underlying biology of pancreatic neoplasia. These advances have not only confirmed the traditional histologic classification system, but also opened new doors to early diagnosis and targeted treatment.

CONCLUSION

This review discusses the histopathology, genetic and epigenetic alterations and potential treatment targets of the five major malignant pancreatic tumors - pancreatic ductal adenocarcinoma, pancreatic neuroendocrine tumor, solid-pseudopapillary neoplasm, acinar cell carcinoma and pancreatoblastoma.

TP53 alterations in pancreatic acinar cell carcinoma: new insights into the molecular pathology of this rare cancer

The molecular alterations of pancreatic acinar cell carcinomas (ACCs) are poorly understood and have been reported as being different from those in ductal adenocarcinomas. Loss of TP53 gene function in the pathogenesis of ACCs is controversial since contradictory findings have been published. A comprehensive analysis of the different possible genetic and epigenetic mechanisms leading to TP53 alteration in ACC has never been reported and hence the role of TP53 in the pathogenesis and/or progression of ACC remains unclear. We investigated TP53 alterations in 54 tumor samples from 44 patients, including primary and metastatic ACC, using sequencing analysis, methylation-specific multiplex ligation probe amplification, fluorescence in situ hybridization, and immunohistochemistry. TP53 mutations were found in 13 % of primary ACCs and in 31 % of metastases. Primary ACCs and metastases showed the same mutational profile, with the exception of one case, characterized by a wild-type sequence in the primary carcinoma and a mutation in the corresponding metastasis. FISH analysis revealed deletion of the TP53 region in 53 % of primary ACCs and in 50 % of metastases. Promoter hypermethylation was found in one case. The molecular alterations correlated well with the immunohistochemical findings. A statistically significant association was found between the combination of mutation of one allele and loss of the other allele of TP53 and worse survival.

Aberrant DNA methylation profiles of inherited and sporadic colorectal cancer

Background

Aberrant DNA methylation has been widely investigated in sporadic colorectal carcinomas (CRCs), and extensive work has been performed to characterize different methylation profiles of CRC. Less information is available about the role of epigenetics in hereditary CRC and about the possible clinical use of epigenetic biomarkers in CRC, regardless of the etiopathogenesis. Long interspersed nucleotide element 1 (LINE-1) hypomethylation and gene-specific hypermethylation of 38 promoters were analyzed in multicenter series of 220 CRCs including 71 Lynch (Lynch colorectal cancer with microsatellite instability (LS-MSI)), 23 CRCs of patients under 40 years in which the main inherited CRC syndromes had been excluded (early-onset colorectal cancer with microsatellite stability (EO-MSS)), and 126 sporadic CRCs, comprising 28 cases with microsatellite instability (S-MSI) and 98 that were microsatellite stable (S-MSS). All tumor methylation patterns were integrated with clinico-pathological and genetic characteristics, namely chromosomal instability (CIN), TP53 loss, BRAF, and KRAS mutations.

Results

LS-MSI mainly showed absence of extensive DNA hypo- and hypermethylation. LINE-1 hypomethylation was observed in a subset of LS-MSI that were associated with the worse prognosis. Genetically, they commonly displayed G:A transition in the KRAS gene and absence of a CIN phenotype and of TP53 loss. S-MSI exhibited a specific epigenetic profile showing low rates of LINE-1 hypomethylation and extensive gene hypermethylation. S-MSI were mainly characterized by MLH1 methylation, BRAF mutation, and absence of a CIN phenotype and of TP53 loss. By contrast, S-MSS showed a high frequency of LINE-1 hypomethylation and of CIN, and they were associated with a worse prognosis. EO-MSS were a genetically and epigenetically heterogeneous group of CRCs. Like LS-MSI, some EO-MSS displayed low rates of DNA hypo- or hypermethylation and frequent G:A transitions in the KRAS gene, suggesting that a genetic syndrome might still be unrevealed in these patients. By contrast, some EO-MSS showed similar features to those observed in S-MSS, such as LINE-1 hypomethylation, CIN, and TP53 deletion. In all four classes, hypermethylation of ESR1, GATA5, and WT1 was very common.

Conclusions

Aberrant DNA methylation analysis allows the identification of different subsets of CRCs. This study confirms the potential utility of methylation tests for early detection of CRC and suggests that LINE-1 hypomethylation may be a useful prognostic marker in both sporadic and inherited CRCs.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-015-0165-2) contains supplementary material, which is available to authorized users.

Disruption of the APC gene by t(5;7) translocation in a Turcot family

Turcot syndrome (TS) refers to the combination of colorectal polyps and primary tumours of the central nervous system. TS is a heterogeneous genetic condition due to APC and/or mismatch repair germline mutations. When APC is involved the vast majority of mutations are truncating, but in approximately 20%-30% of patients with familial polyposis no germline mutation can be found. A 30-year-old Caucasian woman with a positive pedigree for TS was referred to our Genetic Counselling Service. She was negative for APC and MUTYH but showed a reciprocal balanced translocation t(5;7)(q22;p15) at chromosome analysis. FISH analysis using specific BAC probes demonstrated that 5q22 breakpoint disrupted the APC gene. Transcript analysis by MLPA and digital PCR revealed that the cytogenetic rearrangement involving the 3' end of the APC gene caused a defective expression of a truncated transcript. This result allowed cytogenetic analysis to be offered to all the other family members and segregation analysis clearly demonstrated that all the carriers were affected, whereas non-carriers did not have the polyposis. A cytogenetic approach permitted the identification of the mutation-causing disease in this family, and the segregation analysis together with the transcript study supported the pathogenetic role of this mutation. Karyotype analysis was used as a predictive test in all members of this family. This family suggests that clinically positive TS and FAP cases, which test negative with standard molecular analysis, could be easily and cost-effectively resolved by a classical and molecular cytogenetic approach.

A Revised Classification System and Recommendations From the Baltimore Consensus Meeting for Neoplastic Precursor Lesions in the Pancreas

International experts met to discuss recent advances and to revise the 2004 recommendations for assessing and reporting precursor lesions to invasive carcinomas of the pancreas, including pancreatic intraepithelial neoplasia (PanIN), intraductal papillary mucinous neoplasm (IPMN), mucinous cystic neoplasm, and other lesions. Consensus recommendations include the following: (1) To improve concordance and to align with practical consequences, a 2-tiered system (low vs. high grade) is proposed for all precursor lesions, with the provision that the current PanIN-2 and neoplasms with intermediate-grade dysplasia now be categorized as low grade. Thus, "high-grade dysplasia" is to be reserved for only the uppermost end of the spectrum ("carcinoma in situ"-type lesions). (2) Current data indicate that PanIN of any grade at a margin of a resected pancreas with invasive carcinoma does not have prognostic implications; the clinical significance of dysplasia at a margin in a resected pancreas with IPMN lacking invasive carcinoma remains to be determined. (3) Intraductal lesions 0.5 to 1 cm can be either large PanINs or small IPMNs. The term "incipient IPMN" should be reserved for lesions in this size with intestinal or oncocytic papillae or GNAS mutations. (4) Measurement of the distance between an IPMN and invasive carcinoma and sampling of intervening tissue are recommended to assess concomitant versus associated status. Conceptually, concomitant invasive carcinoma (in contrast with the "associated" group) ought to be genetically distinct from an IPMN elsewhere in the gland. (5) "Intraductal spread of invasive carcinoma" (aka, "colonization") is recommended to describe lesions of invasive carcinoma invading back into and extending along the ductal system, which may morphologically mimic high-grade PanIN or even IPMN. (6) "Simple mucinous cyst" is recommended to describe cysts >1 cm having gastric-type flat mucinous lining at most minimal atypia without ovarian-type stroma to distinguish them from IPMN. (7) Human lesions resembling the acinar to ductal metaplasia and atypical flat lesions of genetically engineered mouse models exist and may reflect an alternate pathway of carcinogenesis; however, their biological significance requires further study. These revised recommendations are expected to improve our management and understanding of precursor lesions in the pancreas.

Molecular Features and Methylation Status in Early Onset (≤40 Years) Colorectal Cancer: A Population Based, Case-Control Study

Colorectal cancer is usually considered a disease of the elderly. However, a small fraction of patients develops colorectal cancer earlier. The aim of our study was to define the frequency of known hereditary colorectal syndromes and to characterise genetic and epigenetic features of early nonhereditary tumors. Thirty-three patients ≤40 years with diagnosis of colorectal cancer and 41 patients with disease at >60 years of age were investigated for MSI, Mismatch Repair proteins expression, KRAS and BRAF mutations, hypermethylation, and LINE-1 hypomethylation. Detection of germline mutations was performed in Mismatch Repair, APC and MUTYH genes. Early onset colorectal cancer showed a high incidence of hereditary forms (18%). KRAS mutations were detected in 36% of early nonhereditary tumors. Early onset colorectal cancer disclosed an average number of methylated genes significantly lower when compared to the controls (p = 0.02). Finally both of the two groups were highly methylated in ESR1, GATA5, and WT1 genes and were similar for LINE-1 hypomethylation. The genetic make-up of carcinomas differs from young to elderly patients. Early onset tumors showed more frequently a constitutional defective of Mismatch Repair System and a minor number of methylated genes. Hypermethylation of ESR1, GATA5, and WT1 genes suggests possible markers in the earlier diagnosis of colorectal tumorigenesis.

The APC I1307K allele conveys a significant increased risk for cancer

This study is the first attempt to evaluate the association between the APC I1307K variant and overall cancer risk. It is unique in both its large sample size and in the reliability of data in the control group. The findings described in this article have major implications in terms of identifying asymptomatic individuals who are at increased risk to harbor cancer and therefore targeted to be enrolled in specific early detection and prevention programs. The prevalence of the APC I1307K missense mutation among Ashkenazi Jews is ∼ 6%. Carriers are at an increased risk for colorectal neoplasia. In this study, we examined the association of this variant with non-colorectal cancers. Consecutive 13,013 healthy subjects who underwent screening at the Integrated Cancer Prevention Center between 2006 and 2014 were enrolled. This population was supplemented with 1,611 cancer patients from the same institution. Demographics, medical history, and pathological data were recorded. Mortality data were obtained from the Ministry of Health's registry. The prevalence of APC I1307K in cancer patients and healthy subjects was compared. The APC I1307K variant was detected in 189 (11.8%) cancer patients compared to 614 (4.7%) healthy subjects, reflecting an adjusted age and sex odds ratio (OR) of 2.53 (p < 0.0001). History of two or more cancer types was associated with a positive carrier prevalence (OR = 4.38 p < 0.0001). Males had significantly increased carrier prevalence in lung, urologic, pancreatic, and skin cancers. The carrier prevalence among females was significantly higher only in breast and skin cancers. Female carriers developed cancer at a significantly older age compared to non-carriers (average 62.7 years vs. 57.8, respectively, p = 0.027), had better survival rates (HR = 0.58, p = 0.022) and overall increased longevity (average age of death 78.8 vs. 70.4 years, respectively, p = 0.003). In conclusion, the APC I1307K variant is a reliable marker for overall cancer risk (OR 2.53). Further studies are needed to evaluate its use for specific cancer types-particularly in males. Female carriers have better prognosis and increased lifespan.

Durable recurrence-free survival after pneumonectomy for late lung metastasis from rectal cancer: case report with genetic and epigenetic analyses

BACKGROUND

Treatment of pulmonary recurrence from colorectal cancer involving the main bronchus usually entails palliation using interventional bronchoscopy, because the prognosis is generally very poor. Surgical experience has clarified that in this setting pneumonectomy should only be performed in carefully selected patients showing favorable prognostic profiles (defined by low carcinoembryonic antigen serum levels pre-thoracotomy), solitary and completely resectable pulmonary metastasis, and long disease-free intervals. In the few long-term survivors after pneumonectomy for late-recurrent colorectal cancer, the disease has a relatively indolent metastatic course and genetic and epigenetic profiling may provide further insight regarding tumor evolution.

CASE PRESENTATION

We describe a rare case of late hilar-endobronchial and lymph nodal recurrence of rectal cancer, sequential to hepatic metastasectomy, that we successfully treated with pneumonectomy and chemotherapy (leucovorin, 5-fluorouracil and oxaliplatin regimen); the patient achieved 7-year relapse-free survival after lung metastasectomy and 24-year overall survival after primary rectal cancer resection. To our knowledge, this is the longest survival reported after sequential liver resection and pneumonectomy for recurrent colorectal cancer. In our case the primary rectal cancer and its recurrences showed identical immunohistochemical patterns. The primary rectal cancer and the matched metastases (hepatic, pulmonary and lymph nodal) demonstrated no KRAS, NRAS, BRAF and PIK3CA mutations, a microsatellite stable phenotype, and no tumor protein p53 alterations or recurrent copy number alterations on chromosome 8. High genetic concordances between the paired primary tumor and metastases suggest that the key tumor biological traits remained relatively conserved in the three metastatic sites. Minor differences in gene specific hypermethylation were observed between the primary tumor and lung and nodal metastases. These differences suggest that epigenetic mechanisms may be causally involved in the microenvironmental regulation of cancer metastasis.

CONCLUSION

The exceptionally long survival of the patient in our case study involving favorable clinical features was related to an excellent response to surgery and adjuvant chemotherapy; however, genetic or epigenetic factors that remain unidentified cannot be excluded as contributory factors. Our findings support the concept of a common clonal origin of the primary cancer and synchronous and late metastases, and suggest that aberrant DNA methylation may regulate tumor dormancy mechanisms.

Role of cellular cytoskeleton in epithelial-mesenchymal transition process during cancer progression

Currently, cancer metastases remain a major clinical problem that highlights the importance of recognition of the metastatic process in cancer diagnosis and treatment. A critical process associated with the metastasis process is the transformation of epithelial cells toward the motile mesenchymal state, a process called epithelial-mesenchymal transition (EMT). Increasing evidence suggests the crucial role of the cytoskeleton in the EMT process. The cytoskeleton is composed of the actin cytoskeleton, the microtubule network and the intermediate filaments that provide structural design and mechanical strength that is necessary for the EMT. The dynamic reorganization of the actin cytoskeleton is a prerequisite for the morphology, migration and invasion of cancer cells. The microtubule network is the cytoskeleton that provides the driving force during cell migration. Intermediate filaments are significantly rearranged, typically switching from cytokeratin-rich to vimentin-rich networks during the EMT process, accompanied by a greatly enhanced cell motility capacity. In the present review, the recent novel insights into the different cytoskeleton underlying EMT are summarized. There are numerous advances in our understanding of the fundamental role of the cytoskeleton in cancer cell invasion and migration.

Acinar Cell Carcinoma of the Pancreas: Overview of Clinicopathologic Features and Insights into the Molecular Pathology

Acinar cell carcinomas (ACCs) of the pancreas are rare pancreatic neoplasms accounting for about 1–2% of pancreatic tumors in adults and about 15% in pediatric subjects. They show different clinical symptoms at presentation, different morphological features, different outcomes, and different molecular alterations. This heterogeneous clinicopathological spectrum may give rise to difficulties in the clinical and pathological diagnosis with consequential therapeutic and prognostic implications. The molecular mechanisms involved in the onset and progression of ACCs are still not completely understood, although in recent years, several attempts have been made to clarify the molecular mechanisms involved in ACC biology. In this paper, we will review the main clinicopathological and molecular features of pancreatic ACCs of both adult and pediatric subjects to give the reader a comprehensive overview of this rare tumor type.

Acinar cell carcinomas of the pancreas: a molecular analysis in a series of 57 cases

Pancreatic acinar cell carcinomas (PACs) are rare but are distinct aggressive neoplasms that phenotypically differ from pancreatic ductal adenocarcinomas (PDACs) and pancreatic neuroendocrine neoplasms (PNENs). Despite recent work on the genetic changes of PACs, their molecular pathogenesis is still poorly understood. In this study, we focus on a comparative genomic hybridization analysis. Based on frequent chromosomal imbalances, the involvement of DCC and c-MYC in the pathogenesis of PACs is further investigated. Moreover, we examine markers harboring potential therapeutic relevance (K-RAS, BRAF, EGFR, MGMT, HSP90, L1CAM, Her2). PACs revealed a microsatellite stable, chromosomal unstable genotype, defined by recurrent chromosomal losses of 1p, 3p, 4q, 5q, 6q, 8p, 9p, 11q, 13q, 16q, and 18, as well as gains of 1q, 7, 8q, 12, 17q, and 20q. Subsets of PAC displayed reduction/loss of DCC (79 %) and c-MYC-amplification (17 %). Significant EGFR expression occurred in 42 %, HSP90 expression in 98 %, L1CAM expression in 72 %, and loss of MGMT in 26 %. Two cases carried a K-RAS mutation. Mutations of EGFR or BRAF were not detected. All cases were Her2/neu-negative. PACs display characteristic chromosomal imbalances which are distinctly different from those in pancreatic ductal adenocarcinomas and pancreatic neuroendocrine neoplasms. Our findings suggest that DCC and c-MYC alterations may play an important role in the pathogenesis of PACs. Furthermore, EGFR, MGMT, HSP90, and L1CAM may be useful as therapeutic markers and predictors of response to therapy in a subset of PACs.

Pathology and genetics of pancreatic neoplasms with acinar differentiation

Pancreatic neoplasms with acinar differentiation, including acinar cell carcinoma, pancreatoblastoma, and carcinomas with mixed differentiation, are distinctive pancreatic neoplasms with a poor prognosis. These neoplasms are clinically, pathologically, and genetically unique when compared to other more common pancreatic neoplasms. Most occur in adults, although pancreatoblastomas usually affect children under 10 years old. All of these neoplasms exhibit characteristic histologic features including a solid or acinar growth pattern, dense neoplastic cellularity, uniform nuclei with prominent nucleoli, and granular eosinophilic cytoplasm. Exocrine enzymes are detectable by immunohistochemistry and, for carcinomas with mixed differentiation, neuroendocrine or ductal lineage markers are also expressed. The genetic alterations of this family of neoplasms largely differ from conventional ductal adenocarcinomas, with only rare mutations in TP53, KRAS, and p16, but no single gene or neoplastic pathway is consistently altered in acinar neoplasms. Instead, there is striking genomic instability, and a subset of cases has mutations in the APC/β-catenin pathway, mutations in SMAD4, RAF gene family fusions, or microsatellite instability. Therapeutically targetable mutations are often present. This review summarizes the clinical and pathologic features of acinar neoplasms and reviews the current molecular data on these uncommon tumors.

Diagnosis and molecular aspects of solid-pseudopapillary neoplasms of the pancreas

Solid-pseudopapillary neoplasm of the pancreas (SPN) is an uncommon low-grade malignant neoplasm occurring mostly in young women. In addition to its distinctive pathological appearance of pseudopapillae with poorly cohesive neoplastic cells, rare variants exist raising the differential diagnosis especially with neuroendocrine neoplasms. The overall prognosis for patients with SPNs is excellent after surgical resection. Nevertheless, 10% of cases may have malignant behavior characterized by tumor recurrence and/or metastasis. Despite numerous studies, the histogenesis of this neoplasm remains unclear. Distinctive molecular alterations such as the presence of CTNNB1 mutations are observed in nearly all cases, while mutations classically observed in ductal adenocarcinoma, such as KRAS, TP53, and SMAD4, are not observed in SPNs, reinforcing its distinct nature compared to all other pancreatic neoplasms. Recent transcriptional studies have shown that activation of the Wnt/beta-catenin pathway in these tumors is associated with the upregulation of genes belonging to Notch, Hedgehog, and androgen receptor signaling pathways.

Prognostic relevance of aberrant DNA methylation in g1 and g2 pancreatic neuroendocrine tumors

BACKGROUND/AIMS

The occurrence and clinical relevance of DNA hypermethylation and global hypomethylation in pancreatic neuroendocrine tumours (PanNETs) are still unknown. We evaluated the frequency of both epigenetic alterations in PanNETs to assess the relationship between methylation profiles and chromosomal instability, tumour phenotypes and prognosis.

METHODS

In a well-characterized series of 56 sporadic G1 and G2 PanNETs, methylation-sensitive multiple ligation-dependent probe amplification was performed to assess hypermethylayion of 33 genes and copy number alterations (CNAs) of 53 chromosomal regions. Long interspersed nucleotide element-1 (LINE-1) hypomethylation was quantified by pyrosequencing.

RESULTS

Unsupervised hierarchical clustering allowed to identify a subset of 22 PanNETs (39%) exhibiting high frequency of gene-specific methylation and low CNA percentages. This tumour cluster was significantly associated with stage IV (p = 0.04) and with poor prognosis in univariable analysis (p = 0.004). LINE-1 methylation levels in PanNETs were significantly lower than in normal samples (p < 0.01) and were approximately normally distributed. 12 tumours (21%) were highly hypomethylated, showing variable levels of CNA. Interestingly, only 5 PanNETs (9%) were observed to show simultaneously LINE-1 hypomethylation and high frequency of gene-specific methylation. LINE-1 hypomethylation was strongly correlated with advanced stage (p = 0.002) and with poor prognosis (p < 0.0001). In the multivariable analysis, low LINE-1 methylation status and methylation clusters were the only independent significant predictors of outcome (p = 0.034 and p = 0.029, respectively).

CONCLUSION

The combination of global DNA hypomethylation and gene hypermethylation analyses may be useful to define distinct subsets of PanNETs. Both alterations are common in PanNETs and could be directly correlated with tumour progression.