Learning Radiology xray montage

Carcinoma of the Colon


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 uterine ca
  • 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)


  • Adenocarcinomas make up the vast majority
  • Squamous cell carcinoma can start at the anal verge
  • Cloacogenic carcinoma spreads mostly by direct invasion

Clinical Findings

  • Peak age 50-70 years
  • Weight loss
  • Blood in stool
  • Loss of appetite
  • Change in  bowel habits  


  • 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 

Imaging findings 

  • 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 


  • 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 from Colon Cancer

  • Liver (25%)
  • Retroperitoneal and mesenteric nodes (15%)
  • Hydronephrosis (13%)
  • Adrenal (10%)
  • Ovarian mets
  • Ascites 

 carcinoma colon

Colonic Carcinoma, Apple-Core Sign. An encircling mass in the mid-transverse colon (red arrow) mostly obstructs the retrograde flow of the barium in this single-contrast barium enema. The shelf-like defect caused by the distal end of the mass (white arrows) produces half of the "apple-core" sign of colon carcinoma.