·        Risk Factors

o          Adenomatous polyp

o          Family history of benign or malignant colon tumors

o          Chronic ulcerative colitis

o          Crohn’s disease

o          Prior pelvic radiation

o          In women who have carcinoma of breast or uterus

o          Retinitis pigmentosa

o          Familial polyposis

o          Gardener’s syndrome

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

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

 

·        Pathology

o          Adenocarcinomas make up the vast majority

o          Squamous cell carcinoma can start at the anal verge

o          Cloacogenic carcinoma spreads mostly by direct invasion

 

·        Clinical

o          Peak age 50-70 years

o          Weight loss

o          Blood in stool

o          Loss of appetite

o          Change in  bowel habits

 

·        Location

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

o          Location seems to be changing and moving back to cecum

o          More common in right colon with advancing years

o          More common in left colon with chronic ulcerative colitis

 

 ·        Imaging findings 

o                90-95% rate of detection by BE

o                Polypoid filling defect

o                Annular constricting=apple-core lesion

 

Spot film from a double contrast barium enema of the rectum and distal sigmoid colon
demonstrates a typical annular constricting carcinoma of the colon
with overhanging edges on both the proximal and distal margins forming a so called "apple-core" lesion.

Click here for enlarged photo

 

 

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

o                Calcifications-rare

o                May have retrograde without antegrade obstruction

 

·        Mets to colon

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

o                May also spread via intraperitoneal seeding, especially from ovary

 

·        Complications

o                Obstruction-antegrade/retrograde or both

o                Perforation is relatively common

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

o                Intussusception of lesions in TI or cecum

o                Ischemic colitis may occur if chronic obstruction 

 

·        Metastases

o                Liver (25%)

o                Retroperitoneal and mesenteric nodes (15%)

o                Hydronephrosis (13%)

o                Adrenal (10%)

o                Ovarian mets

o               Ascites

 

·        Complications

o                Obstruction-may be retrograde but not antegrade

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

o                Perforation

o                Intussusception

o                Pneumatosis intestinalis