Adenomas

Familial Polyposis Syndrome

* 500-2500 colonic adenomas * Most are tubular adenomas * Almost 100% risk of colonic ca * Genetic defect on chromosome 5q21 * Become evident in adolescence or early adulthood

Colorectal carcinogenesis

* Adenomatous polyposis coli: APC tumor suppressor gene, FAP, Gardner's syndrome * Hereditary nonpolyposis colon carcinoma: mutations in several genes involved in DNA repair * Methylation abnormalities : loss of methyl groups in DNA of colonic neoplasms * K-ras Gene: Mutated gene that plays a role in intracellular signal transduction * P53: tumor suppressor gene which is mutated

Adenomas clinical features

* All arise from epithelial proliferation and dysplasia * Dysplasia ranges from mild to severe * Most invasive colorectal ca arise from adentomatous lesions

Gardener's Syndrome

* Colonic polyposis * Multiple osteomas of the skull and mandible * Keratinous cysts of skin * Soft tissue tumors: fibromatosis * Almost 100% risk of colonic ca

Hereditary non-polyposis colorectal cancer

* Increased risk of colorectal ca * Increased risk of extraintestinal ca esp. Endometrial ca * Adenomas occur in low numbers but earlier than in general pop. * Colonic malignancies do not arise in preexisting adenomas

Adenomas - clinical features

* Smaller adenomas usually asymptomatic * Villous adenomas more symptomatic due to increased bleeding * Distal villous adenomas may secrete protein and potassium leading to hypoproteinemia or hypokalemia * Because of malignant potential all adenomas should be removed and examined histologically

Tubulovillous Adenomas

* broad mix of tubular and villous area * villous component must be examined carefully for signs of dysplasia

Villous adenomas

* larger, more ominous, sessile may have marked dysplasia * invasive ca also found * frequency of ca correlates with size of polyp

Tubular Adenomas

* most common, most are small and pedunculated * least likely to have cancer

Colorectal adenocarcinoma has many predisposing factors such as

* ulcerative colitis * familial polyposis syndrome * adenomatous villous polyps * genetic factors * low fiber/high fat diet

Adenomas occur most often over the age of

60

Colorectal adenocarcinoma peaks at what age?

60th and 70th

Are males and females equally affected by Adenomas?

Yes

Adenomas most often occur in the following organ

colon

Colorectal adenocarcinoma is the most common malignancy found in the

colon