David S. Klimstra

Cetuximab Shows Activity in Colorectal Cancer Patients With Tumors That Do Not Express the Epidermal Growth Factor Receptor by Immunohistochemistry

PURPOSE To establish evidence of activity, or lack thereof, of cetuximab-based therapy in patients with refractory colorectal cancer with tumors that do not demonstrate epidermal growth factor receptor (EGFR) expression by immunohistochemistry (IHC). PATIENTS AND METHODS Pharmacy computer records were reviewed to identify all patients who received cetuximab at Memorial Sloan-Kettering Cancer Center in a nonstudy setting during the first 3 months of cetuximabs commercial availability. Medical records of these patients were then reviewed to identify colorectal cancer patients who had experienced failure with a prior irinotecan-based regimen and who had a pathology report indicating an EGFR-negative tumor by IHC. Pathology slides from these patients were reviewed by a reference pathologist to confirm EGFR negativity, and computed tomography scans during cetuximab-based therapy were reviewed by a reference radiologist. Response rates were reported using WHO criteria. RESULTS Sixteen chemotherapy-refractory, EGFR-negative colorectal cancer patients who received cetuximab in a nonstudy setting were identified. Fourteen of these patients received cetuximab plus irinotecan, and two received cetuximab monotherapy. In the 16 patients, four major objective responses were seen (response rate, 25%; 95% CI, 4% to 46%). CONCLUSION Colorectal cancer patients with EGFR-negative tumors have the potential to respond to cetuximab-based therapies. EGFR analysis by current IHC techniques does not seem to have predictive value, and selection or exclusion of patients for cetuximab therapy on the basis of currently available EGFR IHC does not seem warranted.

DAXX/ATRX, MEN1, and mTOR pathway genes are frequently altered in pancreatic neuroendocrine tumors.

A rare but deadly form of human pancreatic cancer harbors mutations in chromatin remodeling genes. Pancreatic neuroendocrine tumors (PanNETs) are a rare but clinically important form of pancreatic neoplasia. To explore the genetic basis of PanNETs, we determined the exomic sequences of 10 nonfamilial PanNETs and then screened the most commonly mutated genes in 58 additional PanNETs. The most frequently mutated genes specify proteins implicated in chromatin remodeling: 44% of the tumors had somatic inactivating mutations in MEN1, which encodes menin, a component of a histone methyltransferase complex, and 43% had mutations in genes encoding either of the two subunits of a transcription/chromatin remodeling complex consisting of DAXX (death-domain–associated protein) and ATRX (α thalassemia/mental retardation syndrome X-linked). Clinically, mutations in the MEN1 and DAXX/ATRX genes were associated with better prognosis. We also found mutations in genes in the mTOR (mammalian target of rapamycin) pathway in 14% of the tumors, a finding that could potentially be used to stratify patients for treatment with mTOR inhibitors.

Pancreatic intraepithelial neoplasia: a new nomenclature and classification system for pancreatic duct lesions.

Proliferative epithelial lesions in the smaller caliber pancreatic ducts and ductules have been the subject of numerous morphologic, clinical, and genetic studies; however, a standard nomenclature and diagnostic criteria for classifying these lesion have not been established. To evaluate the uniformity of existing systems for grading duct lesions in the pancreas, 35 microscopic slides with 35 representative duct lesions were sent to eight expert pathologists from the United States, Canada, and Europe. Kappa values for interobserver agreement could not be calculated initially because more than 70 different diagnostic terms were used by the eight pathologists. In several cases, the diagnoses rendered for a single duct lesion ranged from “hyperplasia,” to “metaplasia,” to “dysplasia,” to “carcinoma in situ.” This review therefore demonstrated the need for a standard nomenclature and classification system. Subsequently, during a working group meeting, the pathologists agreed to adopt a single standard system. The terminology pancreatic intraepithelial neoplasia (or PanIN) was selected, and diagnostic criteria for each grade of PanIN were established (http://pathology.jhu.edu/pancreas_panin). This new system was then evaluated by having the eight pathologists rereview the original 35 cases. Only seven different diagnoses were rendered, and kappa values of 0.43, 0.14, and 0.42 were obtained for PanINs 1, 2, and 3 respectively. Cases assigned other diagnoses (e.g., squamous metaplasia) collectively had a kappa value of 0.41. These results show both the potential of the classification system, and also the difficulty of classifying these lesions even with a consistent nomenclature. However, even when there is lack of consensus, having a restricted set of descriptions and terms allows a better understanding of the reasons for disagreement. It is suggested that we adopt and apply this system uniformly, with continued study of its reliability and use, and possibly further refinement. The acceptance of a standard classification system will facilitate the study of pancreatic duct lesions, and will lead ultimately to a better understanding of their biologic importance.

Staging, Resectability, and Outcome in 225 Patients With Hilar Cholangiocarcinoma

ObjectiveTo analyze resectability and survival in patients with hilar cholangiocarcinoma according to a proposed preoperative staging scheme that fully integrates local, tumor-related factors. Summary Background DataIn patients with hilar cholangiocarcinoma, long-term survival depends critically on complete tumor resection. The current staging systems ignore factors related to local tumor extent, preclude accurate preoperative disease assessment, and correlate poorly with resectability and survival. MethodsDemographics, results of imaging studies, surgical findings, pathology, and survival were analyzed prospectively in consecutive patients. Using data from imaging studies, all patients were placed into one of three stages based on the extent of ductal involvement by tumor, the presence or absence of portal vein compromise, and the presence or absence of hepatic lobar atrophy. ResultsFrom March 1991 through December 2000, 225 patients were evaluated, 77% of whom were seen and treated within the last 6 years. Sixty-five patients had unresectable disease; 160 patients underwent exploration with curative intent. Eighty patients underwent resection: 62 (78%) had a concomitant hepatic resection and 62 (78%) had an R0 resection (negative histologic margins). Negative histologic margins, concomitant partial hepatectomy, and well-differentiated tumor histology were associated with improved outcome after all resections. However, in patients who underwent an R0 resection, concomitant partial hepatectomy was the only independent predictor of long-term survival. Of the 9 actual 5-year survivors (of 30 at risk), all had a concomitant hepatic resection and none had tumor-involved margins; 3 of these 9 patients remained free of disease at a median follow-up of 88 months. The rates of complications and death after resection were 64% and 10%, respectively. In the 219 patients whose disease could be staged, the proposed system predicted resectability and the likelihood of an R0 resection and correlated with metastatic disease and survival. ConclusionBy taking full account of local tumor extent, the proposed staging system for hilar cholangiocarcinoma accurately predicts resectability, the likelihood of metastatic disease, and survival. Complete resection remains the only therapy that offers the possibility of long-term survival, and hepatic resection is a critical component of the surgical approach.

An illustrated consensus on the classification of pancreatic intraepithelial neoplasia and intraductal papillary mucinous neoplasms

Invasive pancreatic ductal adenocarcinoma is an almost uniformly fatal disease. Several distinct noninvasive precursor lesions can give rise to invasive adenocarcinoma of the pancreas, and the prevention, detection, and treatment of these noninvasive lesions offers the potential to cure early pancreatic cancers. Noninvasive precursors of invasive ductal adenocarcinoma of the pancreas include pancreatic intraepithelial neoplasias (PanINs), intraductal papillary mucinous neoplasms (IPMNs), and mucinous cystic neoplasms. Diagnostic criteria, including a distinct ovarian-type stroma, and a consistent nomenclature are well established for mucinous cystic neoplasms. By contrast, consistent nomenclatures and diagnostic criteria have been more difficult to establish for PanINs and IPMNs. Because both PanINs and IPMNs consist of intraductal neoplastic proliferations of columnar, mucin-containing cells with a variable degree of papilla formation, the distinction between these two classes of precursor lesions remains problematic. Thus, considerable ambiguities still exist in the classification of noninvasive neoplasms in the pancreatic ducts. A meeting of international experts on precursor lesions of pancreatic cancer was held at The Johns Hopkins Hospital from August 18 to 19, 2003. The purpose of this meeting was to define an international acceptable set of diagnostic criteria for PanINs and IPMNs and to address a number of ambiguities that exist in the previously reported classification systems for these neoplasms. We present a consensus classification of the precursor lesions in the pancreatic ducts, PanINs and IPMNs.

The Pathologic Classification of Neuroendocrine Tumors A Review of Nomenclature, Grading, and Staging Systems

Neuroendocrine tumors (NETs) arise in most organs of the body and share many common pathologic features. However, a variety of different organ-specific systems have been developed for nomenclature, grading, and staging of NETs, causing much confusion. This review examines issues in the pathologic assessment of NETs that are common among primaries of different sites. The various systems of nomenclature are compared along with new proposal for grading and staging NETs. Although differences persist, there are many common themes, such as the distinction of well-differentiated (low and intermediate-grade) from poorly differentiated (high-grade) NETs and the significance of proliferative rate in prognostic assessment. A recently published minimum pathology data set is presented to help standardize the information in pathology reports. Although an ultimate goal of standardizing the pathologic classification of all NETs, irrespective of primary site, remains elusive, an understanding of the common themes among the different current systems will permit easier translation of information relevant to prognosis and treatment.

Classification of types of intraductal papillary-mucinous neoplasm of the pancreas: a consensus study

Now that more than two decades have passed since the first reports of intraductal papillary-mucinous neoplasms (IPMNs), it has become clear that IPMN consists of a spectrum of neoplasms with both morphological and immunohistochemical variations. At a meeting of international experts on pancreatic precursor lesions held in 2003, it was agreed that a consensus classification of IPMN subtypes should be established to enable a more detailed analysis of the clinicopathological significance of the variations. Based on our experience and on information from the literature, we selected representative histological examples of IPMNs and defined a consensus nomenclature and criteria for classifying variants as distinctive IPMN subtypes including gastric type, intestinal type, pancreatobiliary type, and oncocytic type. These definitions can be used for further analyses of the clinicopathological significance of the variations of IPMN.

Acinar Cell Carcinoma of the Pancreas: A Clinicopathologic Study of 28 Cases

We have examined the microscopic appearance, immunohistochemical staining properties, and clinical behavior of 28 cases of acinar cell carcinoma of the pancreas. Two of the tumors occurred in children. The adult patients ranged in age from 40 to 81 years (mean, 62 years). Males greatly outnumbered females, and most of the patients were white. Presenting symptoms were nonspecific, and jaundice was infrequent. The frequently reported complications from increased serum lipase levels (i.e., arthralgias and subcutaneous fat necrosis) were present in only 16% of the patients. Grossly, the tumors were relatively circumscribed and fleshy, averaging 10.8 cm, with occasionally extensive hemorrhage and necrosis. Microscopically, the tumors were very cellular and characteristically lacked a desmoplastic stroma. Acinar, solid, trabecular, and glandular patterns of growth were identified; individual tumors were usually mixed. Nuclei were round to oval, with minimal pleomorphism and single prominent nucleoli. Mitotic activity was variable. In general the cytoplasm was moderately abundant, eosinophilic, and granular, but many of the solid tumors had cells with scanty cytoplasm. Characteristic periodic acid-Schiffpositive, diastase-resistant cytoplasmic granules were demonstrated in >90% of the cases, and the butyrate esterase histochemical stain for lipase activity was positive in 73%. Immunohistochemically, there was positivity for trypsin in 100% of the cases, for lipase in 77%, for chymotrypsin in 38%, and for amylase in 31%. A minor endocrine component was recognized with antibodies against chromogranin or islet cell hormones in 42% of the tumors. Ultrastructurally, exocrine secretory features were present, with polarized cells showing microvillilined lumina, abundant rough endoplasmic reticulum, and 125-1,000-nm zymogen-like granules. In addition, many cases showed pleomorphic electron-dense granules measuring up to 3,500 nm and containing fibrillary internal structures. Follow-up information was available in 88% of the cases. Half of the patients had metastatic disease at presentation and an additional 23% subsequently developed metastases, which were usually restricted to the regional lymph nodes and liver. The mean survival for all cases was 18 months, with 1- and 3-year survivals of 57 and 26%, respectively. Patients presenting before age 60 years survived nearly twice as long as older patients did. Stage also influenced prognosis, whereas the histologic subtype of the tumors and the location within the pancreas correlated only weakly with survival.

Solid-Pseudopapillary Tumors of the Pancreas Are Genetically Distinct from Pancreatic Ductal Adenocarcinomas and Almost Always Harbor β-catenin Mutations

Solid-pseudopapillary tumors (SPTs) are unusual pancreatic neoplasms of low malignant potential that most frequently affect young women. Genetic events contributing to the development of SPTs are unknown. Whereas the more common ductal adenocarcinomas of the pancreas essentially never harbor beta-catenin or APC gene mutations, we have recently identified alterations of the APC/beta-catenin pathway in other nonductal pancreatic neoplasms including pancreatoblastomas and acinar cell carcinomas. We analyzed a series of 20 SPTs for somatic alterations of the APC/beta-catenin pathway using immunohistochemistry for beta-catenin protein accumulation, direct DNA sequencing of beta-catenin exon 3, and direct DNA sequencing of the mutation cluster region in exon 15 of the APC gene in those SPTs that did not harbor beta-catenin mutations. Immunohistochemical labeling for cyclin D1 was performed to evaluate the overexpression of this cell-cycle protein as one of the putative downstream effectors of beta-catenin dysregulation. In addition, we analyzed the SPTs for genetic alterations commonly found in pancreatic ductal adenocarcinomas, including mutations in the K-ras oncogene and p53 and DPC4 tumor suppressor genes, using direct DNA sequencing of K-ras and immunostaining for p53 and Dpc4. Almost all SPTs harbored alterations in the APC/beta-catenin pathway. Nuclear accumulation of beta-catenin protein was present in 95% (19 of 20), and activating beta-catenin oncogene mutations were identified in 90% (18 of 20) of the SPTs. Seventy-four percent (14 of 19) showed overexpression of cyclin D1, ranging from 10 to 70% of tumor nuclei. In contrast, no K-ras mutations were present in any of the 20 SPTs, and Dpc4 expression was intact in all 16 SPTs for which immunohistochemical labeling was successful. Overexpression of p53 was limited to only 3 of 19 (15.8%) SPTs. These results emphasize the two distinct, divergent genetic pathways of neoplastic progression in pancreatic ductal and nonductal neoplasms.

Intrahepatic Cholangiocarcinoma : Rising Frequency, Improved Survival, and Determinants of Outcome After Resection

Background:Despite data suggesting a rising worldwide incidence, intrahepatic cholangiocarcinoma (IHC) remains an uncommon disease. This study analyzes changes in IHC frequency, demographics, and treatment outcome in a consecutive and single institutional cohort. Methods:Consecutive patients with confirmed IHC seen and treated over a 16-year period were included. The trend in IHC frequency over the study period was compared with that of hilar cholangiocarcinoma patients (HCCA) seen during the same time. Demographics and patient disposition, histopathologic, treatment, recurrence, and survival data were analyzed; changes in these variables over time were assessed. Results:From December 1990 through July 2006, 594 patients were evaluated (IHC = 270, HCCA = 324). Over the study period, the average annual increase in new IHC patients was 14.2% (P < 0.001). Relative to HCCA, the proportional increase in IHC was nearly 3-fold, and new IHC patients have outnumbered those with HCCA by 2:1 over the last 3 years. Conditions associated with IHC were rarely seen, with only 7 patients having a history of sclerosing cholangitis and/or inflammatory bowel disease and none with hepatolithiasis or biliary parasitic disease; however, heavy tobacco use (27%) and diabetes mellitus (16.4%) were particularly prevalent. The majority of patients were not candidates for resection, most commonly because of advanced hepatic disease. After resection (n = 82), median disease-specific survival was 36 months; recurrence was observed in 62.2% of patients at a median follow-up of 26 months, with the liver remnant involved most frequently (62.7%). Multiple hepatic tumors (P < 0.001), regional nodal involvement (P = 0.012), and large tumor size (P = 0.016) independently predicted poor recurrence-free survival. Most patients (n = 115, 73.7%) with unresectable disease were treated with chemotherapy, either systemic alone (n = 75) or combined with regional hepatic arterial floxuridine (FUDR) (n = 28). Compared with the first 10 years of the study (1990–2000), the last 6 years saw an overall improvement in disease-specific survival for all patients (22 vs. 12 months, P = 0.002), which was particularly notable for patients with unresectable disease (15 vs. 6 months, P = 0.003). Conclusions:At Memorial Sloan-Kettering Cancer Center, IHC incidence has increased dramatically in the last 16 years. Resection offers the best opportunity for long-term survival but is possible in the minority, and patients with large, node-positive or multifocal IHC seem to derive little benefit. Establishing and maintaining control of the intrahepatic disease remains the biggest problem for all IHC patients. The recent increase in survival seems largely because of improved nonoperative therapy for unresectable disease.