Genetic diagnosis of Lynch syndrome II in an extended colorectal cancer-prone family.

Knowledge of colon cancer genetics, with particular attention to precision in hereditary cancer syndrome diagnosis, can often enable highly targeted surveillance and management strategies for patients at high genetic risk. Unfortunately, the patient's family history of cancer is often given minimal attention, and knowledge of hereditary cancer syndromes is frequently limited. Indeed, many physicians still consider familial adenomatous polyposis (FAP) as the only genetic risk factor for colorectal cancer. This concern with FAP was noted in a colorectal cancer-prone kindred which for decades had been thought to manifest that syndrome. However, after meticulous genetic, medical, and pathologic studies, the cardinal phenotypic characteristics of Lynch syndrome II were observed. The potential for cancer control in current and future generations of families like this one clearly mandates the need for computerized registries which could transmit current information about hereditary colon cancer syndrome diagnosis, surveillance, and management.

Phenotypic variation in colorectal adenoma/cancer expression in two families. Hereditary flat adenoma syndrome.

Clinical, pathologic, and genetic studies on two colorectal cancer-prone families have disclosed right-sided colonic flat adenomas and colorectal cancer. Adenomatous polyp counts exceeded those found in hereditary nonpolyposis colorectal cancer (HNPCC) but were fewer than in familial adenomatous polyposis (FAP). Colon cancer occurred at a later age than in HNPCC or FAP and showed right-sided predominance. The older age of patients with colonic cancer, the right-sided predominance of colon cancer, and the paucity of rectal adenomas make FAP unlikely. Vertical transmission of polyps and colon cancer fit the pattern of autosomal dominant inheritance. A characteristic feature of this phenotype is the predominance of flat adenomas. Molecular genetic studies, with careful description of phenotype, should help clarify classification.

Colorectal adenomas in the Lynch syndromes. Results of a colonoscopy screening program.

Forty-four asymptomatic putative Lynch syndrome patients participated in a colonoscopy screening program. There were 18 men and 26 women; mean age was 44 yr. Thirty percent of Lynch syndrome patients had at least one adenoma; 20% had multiple adenomas. In 18% of the patients, adenomas were discovered proximal to the splenic flexure. In a reference group of 88 age- and sex-matched patients, 11% had adenomas, 4% had multiple adenomas, and 1% had right-sided adenomas. Twenty-one Lynch syndrome patients had follow-up colonoscopies. Of 7 patients with adenomas on initial examinations, 6 had adenomas at follow-up. Of 14 patients with negative initial examination results, 3 had adenomas at follow-up. The prevalence of adenomas in the Lynch syndromes is greater than in an unselected reference group. The adenomas are more proximally located, corresponding to the site of cancer distribution in the Lynch syndromes. A high rate of synchronous and metachronous lesions is found. Our findings support the hypothesis that adenomatous changes are the premalignant lesion in the Lynch syndromes. We also found evidence of heterogeneity among Lynch syndrome families in adenoma incidence.

Adenocarcinoma of the small bowel in lynch syndrome II.

Adenocarcinoma of the small bowel is rare and accounts for about 1% of all gastrointestinal tract cancer. This disorder has been identified in association with Crohn's disease, celiac disease, Peutz-Jegher's syndrome, and familial adenomatous polyposis. We report adenocarcinoma of the small bowel in nine patients from eight Lynch syndrome II extended pedigrees. Each affected patient was in the direct genetic lineage or manifested multiple primary cancers (stomach, colon, endometrium, and ovary) consonant with the tumor spectrum of Lynch syndrome II. The average age of onset for small bowel cancer was 47 years (range 31 to 56 years), versus the general population peak occurrence after the sixth decade. We conclude that small bowel cancer may be an integral component of the tumor spectrum of Lynch syndrome II.