A genetic model for colorectal tumorigenesis

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.

https://zenodo.org/record/1230948/files/article.pdf

p53 mutations in human cancers

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.

/pdf/aasld-practice-guideline-management-of-hepatocellular-51bocalv0r.pdf

AASLD PRACTICE GUIDELINE Management of Hepatocellular Carcinoma: An Update

https://aasldpubs.onlinelibrary.wiley.com/doi/pdf/10.1002/hep.20933

Management of hepatocellular carcinoma.

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.

http://science.sciencemag.org/content/sci/274/5293/1672.full.pdf

Cancer Cell Cycles

Molecular genetics of pancreatic cancer

Tumor cell kinetics of human rectal cancer: Relationship between potential doubling time, response to irradiation and chemotherapy, and patterns of failure

Purpose: Preoperative combined-modality therapy for rectal cancer may allow for sphincter preservation, while decreasing recurrence rates and improving the overall prognosis. Oral chemotherapy with uracil and tegafur (UFT) plus leucovorin (LV) may reduce costs and complications associated with protracted infusions of fluorouracil. Our goal was to evaluate the safety of UFT plus LV combined with preoperative radiation and determine the maximum-tolerated dose (MTD) and doselimiting toxicity (DLT) of UFT plus LV in this setting. Patients and Methods: Patients with tumor-nodemetastasis stage II or III rectal cancer received escalating doses of UFT (starting at 250 mg/m 2 /d, with 50mg/m 2 /d increments between consecutive cohorts) and fixed doses of LV (90 mg/d). The UFT and LV combination was given 5 days per week concurrently with a 5-week course of preoperative radiation totaling 45 Gy (1.8 Gy/fraction). Surgery was performed 4 to 6 weeks after radiation and was followed by four 35-day cycles of fixed doses of UFT and LV (28 days of therapy each cycle). Results: Fifteen patients were treated, and 13 received the full preoperative chemotherapy. All planned radiation was delivered successfully. The MTD of UFT with radiation was 350 mg/m 2 /d with 90 mg/d of LV. Diarrhea was the DLT. Sphincter-preserving surgery was performed in 12 of 14 patients. One patient had progressive disease before surgery. Pathologic evaluation of 14 resected specimens showed a complete response in three cases. Conclusion: Preoperative chemoradiation with oral UFT plus LV is feasible and well tolerated and should be further investigated. J Clin Oncol 18:3529-3534. © 2000 by American Society of Clinical Oncology.

Karen R. Cleary

Papers

Molecular genetics of pancreatic cancer

Tumor cell kinetics of human rectal cancer: Relationship between potential doubling time, response to irradiation and chemotherapy, and patterns of failure

Phase I S tudy o f P reoperative O ral U racil a nd T egafur Plus L eucovorin a nd R adiation T herapy i n R ectal C ancer