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Colon Carcinoma

Risk Factors

           • Adenomatous polyp

             • Family history of benign or malignant colon tumors

             • Chronic ulcerative colitis

             • Crohn’s disease

             • Prior pelvic radiation

             • In women who have carcinoma of breast or uterus

             • Retinitis pigmentosa

             • Familial polyposis

             • Gardener’s syndrome

             • For synchronous lesions=1% (two or more colon ca’s at same time)

             • For metachronous lesions=4-5% (likelihood of a person with colon ca developing 2nd)

Pathology

             • Adenocarcinomas make up the vast majority

             • Squamous cell carcinoma can start at the anal verge

             • Cloacogenic carcinoma spreads most by direct invasion

Clinical

             • Peak age 50-70 years

             • Weight loss

             • Blood in stool

             • Loss of appetite

             • Change in  bowel habits

Location

             • Rectum (15%), sigmoid (20%), descending colon (10%), transverse colon (12%), ascending colon (8%), cecum (8%)

             • Location seems to be changing and moving back to cecum

             • More common in right colon with advancing years

             • More common in left colon with chronic ulcerative colitis

X-Ray Manifestations

• 90-95% rate of detection by BE

             • Polypoid filling defect

             • Annular constricting=apple-core lesion

             • Scirrhous ca-rare infiltrating type which gives lead-pipe appearance seen especially in ulcerative colitis

             • Calcifications-rare

             • May have retrograde without antegrade obstruction

Mets to colon

             • Stomach, breast, pancreas, and GU pelvic malignancies via blood

             • May also spread via intraperitoneal seeding, especially from ovary

Complications

             • Obstruction-antegrade/retrograde or both

             • Perforation is relatively common

             • Carcinomas of the transverse colon can spread via direct extension to stomach

             • Intussusception of lesions in TI or cecum

             • Ischemic colitis may occur if chronic obstruction

Metastases

              • Liver (25%)

                • Retroperitoneal and mesenteric nodes (15%)

                • Hydronephrosis (13%)

                • Adrenal (10%)

                • Ovarian mets

                • Ascites

Complications

                • Obstruction-may be retrograde but not antegrade

                        • More likely to be left-sided than right-sided

                • Perforation

                • Intussusception

                • Pneumatosis intestinalis

WH/93

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