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Volume 3, No 4 - Fall 2003

Volume 3, No 4 - Fall 2003

Table of Contents

A Modern Approach to Malignant Hilar Biliary Obstruction
Management of patients with malignant hilar biliary obstruction is challenging for all specialists involved in their care. Evaluation should focus on potential surgical resection, which offers the principal chance of cure; liver transplantation is offered as an experimental treatment at a few centers. Attempt at curative surgical resection is appropriate for selected tumors and often requires partial hepatectomy. Diagnosis and staging is now facilitated by the use of magnetic resonance cholangiopancreatography (MRCP), spiral computed tomography, and endoscopic ultrasonography, which should largely supplant invasive cholangiography. Use of endoscopic retrograde cholangiopancreatography and percutaneous transhepatic cholangiography should be limited primarily to palliation of jaundice in patients with unresectable tumors and to establish tissue diagnoses in ambiguous cases. Palliation of jaundice is optimal with self-expanding metallic stents. Safe and effective drainage can be achieved by using MRCP for targeted endoscopic placement of unilateral metal stents in most cases, with bilateral stents rarely required unless undrained ducts are contaminated. Other palliative modalities for bile duct tumors include surgical bypass, intraluminal and external beam radiation therapy, chemotherapy, and photodynamic therapy. [Rev Gastroenterol Disord. 2003;3(4):187-201]
Postpolypectomy and Post-Cancer Resection Surveillance
Recent guidelines on postpolypectomy surveillance have focused on identifying patients with adenomas who are at high risk for development of significant neoplasms (cancer or “advanced adenoma”) after clearing colonoscopy and should undergo frequent follow-up examinations and those at low risk who require infrequent follow-up examinations. This article reviews the guideline recommendations from the American College of Gastroenterology, American Gastroenterological Association consortium, and the American Cancer Society, and discusses the rationale for the recommended intervals of colonoscopic examinations in low and high-risk postpolypectomy patients. When colorectal cancer is identified, the initial colonoscopic goal in the peri-operative period is to clear the colon of synchronous neoplasms. After this is accomplished, the goal shifts to performance of colonoscopy at intervals that are appropriate for prevention and early detection of second cancers. These intervals often approximate those used in postpolypectomy surveillance. An exception to this approach is patients with rectal cancer operated by traditional blunt dissection techniques, for which there is a rationale for interval flexible sigmoidoscopy and/or rectal ultrasound to look for local recurrences. [Rev Gastroenterol Disord. 2003;3(4):202–209]
The Efficacy of Oral 5-ASAs in the Treatment of Active Ulcerative Colitis: A Systematic Review
The authors set out to critically review the current data on the efficacy of oral 5-aminosalicylic acid (5-ASA) agents for active ulcerative colitis (UC). Thirty-one studies were identified; 19 met entry criteria. Three trials with mesalamine showed statistical significance versus placebo; those with olsalazine or balsalazide did not. No agent was statistically different from sulfasalazine. In 2 of 3 trials of balsalazide versus mesalamine, results for defined primary and secondary endpoints failed to demonstrate statistically significant differences. Studies suggest that mesalamine is superior to placebo for treating active UC. Five-ASA products appear to be as effective as sulfasalazine, but available data do not suggest a difference in efficacy between any of the 5-ASA preparations. [Rev Gastroenterol Disord. 2003;3(4):210-218]
Bioequivalence of Azathioprine Products
All azathioprine oral tablets are considered bioequivalent by the Food and Drug Administration based on traditional testing. However, since these tests were conducted, it has been determined that some patients have a deficiency of the enzyme most responsible for the metabolism of 6-mercaptopurine— thiopurine methyltransferase (TPMT). Azathioprine is rapidly converted to 6-mercaptopurine, its active metabolite. So it is possible that differences in TPMT activity may influence the bioequivalence of azathioprine products among individuals, especially those patients deficient in TPMT enzyme activity. However, this possibility has not been evaluated. [Rev Gastroenterol Disord. 2003;3(4):219-223]