4. Colon cancers result from a series of pathologic changes that
transform normal epithelium into invasive carcinoma. Specific genetic
events, shown by vertical arrows, accompany this multistep process.
5. WHO Classification of CRC
• Adenocarcinoma in situ / severe dysplasia
• Adenocarcinoma
• Mucinous (colloid) adenocarcinoma (>50%
mucinous)
• Signet ring cell carcinoma (>50% signet ring
cells)
• Squamous cell (epidermoid) carcinoma
• Adenosquamous carcinoma
• Small-cell (oat cell) carcinoma
• Medullary carcinoma
• Undifferentiated Carcinoma
6. Risk factors for CRC
• Age
• Adenomas, Polyps
• Sedentary lifestyle, Diet, Obesity
• Family History of CRC
• Inflammatory Bowel Disease (IBD)
• Hereditary Syndromes (familial adenomatous
polyposis (FAP))
7. Dietary factors implicated in
colorectal carcinogenesis
Increased risk
• consumption of red
meat
• animal and saturated
fat
• refined carbohydrates
• alcohol
11. Familial polyposis in which mucosal surface of the colon is a carpet of
small adenomatous polyps. Even though they are small , there is a 100%
risk over time for development of adenocarcinoma, for which total
colectomy is recommended
13. Staging of CRC
• TNM system
• Primary tumor (T)
• Regional lymph nodes (N)
• Distant metastasis (M)
*Note: Tis includes cancer cells confined within the glandular basement
membrane (intraepithelial) or lamina propria (intramucosal) with no
extension through the muscularis mucosae into the submucosa.
**Note: Direct invasion in T4 includes invasion of other segments of the
colorectum by way of the serosa; for example, invasion of the sigmoid colon
by a carcinoma of the cecum.
14. Dukes staging system
A Mucosa 80%
B Into or through M. propria 50%
C1 Into M. propria, + LN ! 40%
C2 Through M. propria, + LN! 12%
D distant metastatic spread <5%
16. Diagnosis
• Colonoscopy is the preferred diagnostic test for
colorectal cancer
• Barium enema and fl exible sigmoidoscopy.
• Biopsy of suspicious lesions is required to establish
a diagnosis.
• Tumor markers such as carcinoembryonic antigen
(cea) or carbohydrate antigen (ca).
• Radiologic studies are used to evaluate the extent of
local disease and to screen for metastatic disease.
17.
18.
19.
20.
21. Therapy
• Surgical resection the only curative treatment
• Likelihood of cure is greater when disease is
detected at an early stage
• Early detection and screening is of pivotal
importance
