HLA and genetic marker studies in adenomatous polyposis

Abstract

of cancer is small, less than 5 per cent. However, only 13 per cent of patients in these series were followed for 20 years as opposed to 46 per cent in Adson's study. Thus, Adson's study has not only an older patient population, but also a significantly longer period of follow up. Both these factors are likely to result in the greater risk for rectal cancer which he observes. The concerns raised in the Mayo series were recently echoed by Watne from the University of West Virginia where rectal cancer has developed in 22 per cent of 32 patients followed up to 20 years with a mean of 14 years.Of greatest interest is how this concern translates into practice at the Mayo Clinic. Since 1950, 299 patients have been seen with familial polyposis. Twenty-six patients presented with metastatic carcinoma or refused treatment, leaving 273 who underwent surgery. One hundred and seventy-three had a colectomy with ileorectostomy, predominantly in more recent years. Clearly this is a well-accepted procedure. If the rectum has many polyps (more than 20) and particularly if these polyps are clustered, rectal excision is preferred. Among the 173 patients having ileorectostomy, 43 developed extensive and increasing rectal polyposis and underwent proctectomy; 26 with a Brook ileostomy, 4 with a Kock pouch, and 13 with an ileoanal anastomosis. DiscussionIt would seem that the concerns raised by the Mayo experience do not necessarily translate into a dramatically different surgical experience. If a patient presents with polyps carpeting the distal rectum, removal is indicated. Fulguration may not adequately remove these multiple polyps, which is not the usual presentation. Most patients will have few polyps in their distal rectum and are good candidates for an ileorectostomy. Careful follow-up will then be required. If clustering or carpeting of the rectum begins to develop, proctectomy is considered, with or without continence preservation.All surgeons recognize the malignant potential of the retained rectum and although the emphasis on malignant potential may vary from one institution to another, I suspect that most surgeons manage their patients by very similar criteria for proctectomy and rectal preservation. References 1.2. 3. 4. 5.6. 7.Moertel CG, Hill

Current status of tumor markers in large bowel cancer

“…The elucidation of the genetic mechanisms underlying them has implications for the screening and detection of the sporadic disease, the etiology of which should be considered to include a genetic as well as an environmental component, although the former may not be evident, for reasons to be discussed, from the apparent population distribution. The search for informative genotypic markers to date has included blood group [32] and histocompatibility (HLA) polymorphisms [33], chromosome analyses [34--36], and extensive studies of skin fibroblasts [37][38][39][40]. Until recently, gene mapping--the identification of linked genetic loci and their assignment to specific chromosomes--has largely relied on the classical approaches of family linkage studies and somatic cell genetics.…”

“…Recently, the intensive search for specific chromosomal and gene abnormalities in the hereditary colon cancer syndromes [33,62] has provided some exciting and promising leads with long-term implications for the identification of individuals at risk not only for the hereditary, but also for the sporadic forms of the disease.…”

Familial adenomatous polyposis: from bedside to bench and vice versa

“…This foundation was able to operate nationwide, and nowadays several autosomal dominant tumor syndromes, including FAP, have been registered (Vasen et al, 1990). In 1979 a possible linkage between FAP and HLA was suggested (Meyers et al, 1979), but subsequent studies failed to confirm this observation (Bodmer et al, 1985;Sasaki et al, 1987). Although the investigation of classical genetic markers, such as blood groups and enzyme polymorphisms, in FAP families has not proven to be helpful in the identification of FAP gene carriers, such studies provided a firm foundation for the successful implementation of linkage analyses and subsequent DNA studies at the level of the adenomatous polyposis coli (APC) gene in those families.…”