Karen R. Cleary

Bio: Karen R. Cleary is an academic researcher from University of Texas MD Anderson Cancer Center. The author has contributed to research in topics: Metastasis & Adenocarcinoma. The author has an hindex of 67, co-authored 158 publications receiving 20453 citations. Previous affiliations of Karen R. Cleary include University of Texas Health Science Center at Houston & University of Florida.

Mutations in the p53 gene occur in diverse human tumour types

Abstract: The p53 gene has been a constant source of fascination since its discovery nearly a decade ago. Originally considered to be an oncogene, several convergent lines of research have indicated that the wild-type gene product actually functions as a tumour suppressor gene. For example, expression of the neoplastic phenotype is inhibited, rather than promoted, when rat cells are transfected with the murine wild-type p53 gene together with mutant p53 genes and/or other oncogenes. Moreover, in human tumours, the short arm of chromosome 17 is often deleted. In colorectal cancers, the smallest common region of deletion is centred at 17p13.1; this region harbours the p53 gene, and in two tumours examined in detail, the remaining (non-deleted) p53 alleles were found to contain mutations. This result was provocative because allelic deletion coupled with mutation of the remaining allele is a theoretical hallmark of tumour-suppressor genes. In the present report, we have attempted to determine the generality of this observation; that is, whether tumours with allelic deletions of chromosome 17p contain mutant p53 genes in the allele that is retained. Our results suggest that (1) most tumours with such allelic deletions contain p53 point mutations resulting in amino-acid substitutions, (2) such mutations are not confined to tumours with allelic deletion, but also occur in at least some tumours that have retained both parental 17p alleles, and (3) p53 gene mutations are clustered in four 'hot-spots' which exactly coincide with the four most highly conserved regions of the gene. These results suggest that p53 mutations play a role in the development of many common human malignancies.

Expression of vascular endothelial growth factor and its receptor, KDR, correlates with vascularity, metastasis, and proliferation of human colon cancer.

Abstract: We studied the correlation between expression of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and their receptors with vascularity, metastasis, and proliferative index of human colon cancers. Immunohistochemical analyses using antibodies against VEGF, bFGF, their receptors (KDR, flt-1, bek, and flg), factor VIII, and proliferating cell nuclear antigen were carried out on archival specimens of 52 human colon carcinomas and 10 adenomas. Vessels were quantitated by light microscopy (x200), and the intensity of staining for VEGF and bFGF was assessed on a scale of 0-3+. The presence or absence of immunostaining for KDR, flt-1, bek, and flg was evaluated in endothelial cells, and proliferation was determined by counting the number of proliferating cell nuclear antigen-positive cells per 500 tumor cells. Expression of VEGF and KDR was higher in metastatic than in nonmetastatic neoplasms and directly correlated with the extent of neovascularization and the degree of proliferation, whereas expression of bFGF, flt-1, bek, and flg did not differ among tumor types. Vessel counts were greater in metastatic tumors than in nonmetastatic tumors. These findings support the hypothesis that VEGF is an important angiogenic factor in primary and metastatic human colon cancer. VEGF expression and vessel counts may aid in predicting patients at risk for metastasis from colon cancer.

Preoperative Gemcitabine-Based Chemoradiation for Patients With Resectable Adenocarcinoma of the Pancreatic Head

Abstract: Purpose We conducted a phase II trial to assess the outcomes of patients who received preoperative gemcitabine-based chemoradiation and pancreaticoduodenectomy (PD) for stage I/II pancreatic adenocarcinoma. Patients and Methods Eligible patients with pancreatic head/uncinate process adenocarcinoma and radiographically defined potentially resectable disease received chemoradiation with 7 weekly intravenous (IV) infusions of gemcitabine (400 mg/m 2 IV over 30 minutes) plus radiation therapy (30 Gy in 10 fractions over 2 weeks). Patients underwent restaging 4 to 6 weeks after completion of chemoradiation and, in the absence of disease progression, were taken to surgery. Results The study enrolled 86 patients. At the time of restaging, disease progression or a decline in performance status precluded 13 patients from surgery. Seventy-three (85%) of 86 patients were taken to surgery, extrapancreatic disease was found in nine, and 64 (74%) of 86 underwent a successful PD. Median overall survival (86 patients) was 22.7 months with a 27% 5-year survival. Median survival was 34 months for the 64 patients who underwent PD and 7 months for the 22 unresected patients (P .001). The 5-year survival for those who did and did not undergo PD was 36% and 0%, respectively. Conclusion Preoperative gemcitabine-based chemoradiation followed by restaging and evaluation for surgery separated the study population into two different subsets: patients likely to benefit from PD (n 64) and those in whom surgery would be unlikely to provide clinical benefit (n 22). Furthermore, the encouraging overall survival observed in this large trial supports the continued investigation of gemcitabine-based preoperative therapy in resectable pancreatic cancer. J Clin Oncol 26:3496-3502. © 2008 by American Society of Clinical Oncology

Preoperative chemoradiation and pancreaticoduodenectomy for adenocarcinoma of the pancreas.

Abstract: Chemoradiation prior to pancreaticoduodenectomy ensures that all patients who undergo resection complete multimodality therapy, avoids resection in patients with rapidly progressive disease, and allows radiation therapy to be delivered to well-oxygenated cells before surgical devascularization. Twenty-eight patients with cytologic or histologic proof of localized adenocarcinoma of the pancreatic head received preoperative chemoradiation (fluorouracil, 300 mg/m2 per day, and 50.4 Gy) with the intent of proceeding to resection; all 28 completed this preoperative therapy. Hospital admission because of gastrointestinal toxic effects was required in nine patients, yet no patient experienced a delay in operation. Restaging was performed 4 to 5 weeks after completion of chemoradiation, and five patients were found to have metastatic disease; the 23 patients without evidence of progressive disease underwent laparotomy. At laparotomy, three patients were found to have unsuspected metastatic disease, three patients had unresectable locally advanced disease, and 17 patients were able to undergo pancreaticoduodenectomy. One perioperative death resulted from myocardial infarction, and perioperative complications occurred in three patients. Histologic evidence of tumor cell injury was present in all resected specimens. Our results suggest that pancreaticoduodenectomy can be performed with a low incidence of complications after chemoradiation for localized adenocarcinoma of the pancreas.

Simplified Staging for Hepatocellular Carcinoma

Abstract: PURPOSE: The current American Joint Committee on Cancer (AJCC) staging system for hepatocellular carcinoma (HCC) fails to stratify patients adequately with respect to prognosis. PATIENTS AND METHOD...

p53 mutations in human cancers

Abstract: Mutations in the evolutionarily conserved codons of the p53 tumor suppressor gene are common in diverse types of human cancer. The p53 mutational spectrum differs among cancers of the colon, lung, esophagus, breast, liver, brain, reticuloendothelial tissues, and hemopoietic tissues. Analysis of these mutations can provide clues to the etiology of these diverse tumors and to the function of specific regions of p53. Transitions predominate in colon, brain, and lymphoid malignancies, whereas G:C to T:A transversions are the most frequent substitutions observed in cancers of the lung and liver. Mutations at A:T base pairs are seen more frequently in esophageal carcinomas than in other solid tumors. Most transitions in colorectal carcinomas, brain tumors, leukemias, and lymphomas are at CpG dinucleotide mutational hot spots. G to T transversions in lung, breast, and esophageal carcinomas are dispersed among numerous codons. In liver tumors in persons from geographic areas in which both aflatoxin B1 and hepatitis B virus are cancer risk factors, most mutations are at one nucleotide pair of codon 249. These differences may reflect the etiological contributions of both exogenous and endogenous factors to human carcinogenesis.

AASLD PRACTICE GUIDELINE Management of Hepatocellular Carcinoma: An Update

Abstract: Since the publication of the American Association for the Study of Liver Diseases (AASLD) practice guidelines on the management of hepatocellular carcinoma (HCC) in 2005, new information has emerged that requires that the guidelines be updated. The full version of the new guidelines is available on the AASLD Web site at http://www.aasld.org/practiceguidelines/ Documents/Bookmarked%20Practice%20Guidelines/ HCCUpdate2010.pdf. Here, we briefly describe only new or changed recommendations.

Cancer Cell Cycles

Abstract: Uncontrolled cell proliferation is the hallmark of cancer, and tumor cells have typically acquired damage to genes that directly regulate their cell cycles. Genetic alterations affecting p16(INK4a) and cyclin D1, proteins that govern phosphorylation of the retinoblastoma protein (RB) and control exit from the G1 phase of the cell cycle, are so frequent in human cancers that inactivation of this pathway may well be necessary for tumor development. Like the tumor suppressor protein p53, components of this "RB pathway," although not essential for the cell cycle per se, may participate in checkpoint functions that regulate homeostatic tissue renewal throughout life.