Web sites and blogs are advising patients that periodic "cleansing" of the colon is necessary to rid the body of toxins.

Levamisole (Janssen), an old antiparasitic drug widely used for treatment of ascariasis in animals, is now available from the National Cancer Institute (NCI) for investigational use with fluorouracil (5-FU; Adrucil; and others) as an adjuvant for treatment of resectable colon cancer that has metastasized to regional lymph nodes (Dukes stage C).

Cetuximab (Erbitux - ImClone Systems/Bristol-Myers Squibb), an epidermal growth factor receptor (EGFR) inhibitor, and bevacizumab (Avastin - Genentech), the first vascular endothelial growth factor angiogenesis inhibitor, have recently been approved by the FDA for treatment of patients with metastatic colorectal cancer. Cetuximab is approved for treatment of patients with EGFR-expressing tumors, either in combination regimens with irinotecan (Camptosar)when the cancer has progressed on irinotecan-based therapy, or as monotherapy for those who cannot tolerate irinotecan. Bevacizumab is approved...

Oxaliplatin (Eloxatin -Sanofi-Synthelabo) has been approved by the FDA for use in combination with fluorouracil (5-FU; Adrucil, and others) and leucovorin (LV; Wellcovorin) for patients with metastatic colorectal cancer whose disease has recurred or progressed despite treatment with 5-FU/LV plus irinotecan (Camptosar - Medical Letter 1997; 39:8).

Currently available techniques for colorectal cancer screening include fecal occult-blood testing, flexible sigmoidoscopy, double contrast barium enema (DCBE) and traditional optical colonoscopy. Optical colonoscopy requires bowel cleansing and sedation, and involves some risk, but is generally accepted as the best available method for detection of lesions and offers the advantage that polyps can be removed when they are identified. A less invasive screening tool, computed tomography (CT) colonography, also known as virtual colonoscopy (VC), offers an additional option.

Options in screening for colon cancer include fecal occult blood tests, flexible sigmoidoscopy, colonoscopy, computed tomography (CT) colonography and fecal DNA tests. Since the last Medical Letter article on this subject, more data have become available on colonography.

An oral formulation of mesalamine (5-aminosalicylic acid, 5-ASA, Asacol - Proctor & Gamble), was recently approved by the US Food and Drug Administration (FDA) for treatment of mildly to moderately active ulcerative colitis; it has not been approved for maintenance of remissions. Olsalazine (Dipentum), a similar drug (Medical Letter, 32:105, 1990), is approved for maintenance of remissions but not for treatment.

Most colorectal cancers arise from localized adenomatous polyps in a process that may take 10 years or more. Early detection and removal of a precancerous colonic lesion (polyp) can prevent cancer from developing.

Balsalazide disodium (Colazal), a prodrug of mesalamine, was marketed in the US this year for oral treatment of mildly to moderately active ulcerative colitis. Oral formulations of mesalamine have been available in the US for nine years for treatment and maintenance of remissions and olsalazine, which is a dimer of mesalamine, is marketed for maintenance of remissions but not for treatment. Balsalazide has been available in Europe for four years.

The FDA has approved Clenpiq (Ferring), a low-volume oral solution that contains sodium picosulfate, magnesium oxide, and anhydrous citric acid, for colon cleansing prior to colonoscopy in adults. The ready-to-drink solution contains the same ingredients as Prepopik, which is supplied as a powder for reconstitution.