Colorectal cancer is the third most common cancer worldwide and in Kenya. It occurs due to uncontrolled cell growth in the colon. Risk factors include family history, inflammatory bowel disease, older age, diet high in red meat and low in fiber, obesity, smoking, and alcohol. Staging involves classifying the tumor size and spread, with stage 4 being tumors that have metastasized to distant organs. Treatment depends on location and stage of the cancer, and may involve surgery, chemotherapy, and radiation therapy. Follow-up care includes regular blood tests, imaging scans, and colonoscopies to monitor for recurrence or spread of the cancer.

1. COLORECTAL CANCER
Dr Winston Makanga, M.B.Ch.B., M.Med. (Surg)
Consultant General and Laparoscopic Surgeon

2. Outline
• Introduction and epidemiology of Colorectal cancer (CRC)
• Surgical anatomy of the colon and rectum
• Classification of colorectal tumors
• Risk factors
• Pathology
• Staging
• Clinical presentation and examination
• Investigation
• Differential diagnosis
• Treatment and follow-up
©Dr Winston

3. Introduction & epidemiology
• Uncontrolled multiplication of cells in the layers of the colon
• Third commonest cancer worldwide (WHO 2022)
• Third commonest cause of cancer related mortality
• Fourth commonest cancer in Kenya (KEMRI)
• M:F ratio 1:1
©Dr Winston

4. Surgical Anatomy
©Dr Winston

5. Surgical anatomy 2 - Mesorectum
©Dr Winston

6. Classification
• Benign tumors
• Polyps (Inflammatory, PZP, Harmatoma, Adenomatous)
• Lipoma
• Hemangioma
• Papilloma
• Neurofibroma
• Malignant
• Primary
• Carcinoma/epithelial
• Lymphoma
• Carcinoid tumor
• Secondary: Direct invasion from adjacent organs, transcoelomic spread
©Dr Winston

7. Risk factors
• Family history…
• Hereditary (10-20%)… the rest are sporadic
• FAPC (polyps) – 1%, AD, APC gene, 21 y/o, Rx - colectomy
• HNPCC (Lynch Syndrome) – 5%, AD, MMR gene
• Inflammatory bowel disease (UC, CD)
• Age >50
• Diet high in animal fat and red meat, low in fibre
• Obesity and sedentary lifestyle
• Smoking, alcohol
• Pelvic irradiation
Preventative
©Dr Winston

8. Pathology
• Most malignancies are epithelial in origin (adenocarcinoma)
• Adenoma to carcinoma sequence ~ 10 years
• Metachronous vs synchronous tumor (5%)
• Macroscopically
• Eccentric mass
• Ulcer
• Annular
• Diffuse infiltrating growth
• Microscopically
• Adenocarcinoma (95%)
• Medullary
• Micropapillary
• Mucinous
• Signet ring
• Others: Lymphoma, GIST, carcinoid
©Dr Winston

9. Spread
• Local
• Lymphatic
• Hematogenous
• Trans-coelomic
©Dr Winston

10. Staging
• Tumor
• T1 – Superficial to muscle layer
• T2 – Invading muscle layer
• T3 – Beyond muscle layer to pericolorectal tissue
• T4 – Invading other organs
• Node
• N0 – no nodal metastasis
• N1 – 1-3 nodes
• N2 – 4 or more nodes
• Metastasis
• M0 – no distant metastasis
• M1 – metastasis to distant organ
Stage 1 – T1/2, N0, M0
Stage 2 – T3/4, N0, M0
Stage 3 – Any T, N1/2, M0
Stage 4 – Any T, Any N, M1
©Dr Winston

11. Clinical presentation
• Right colon
• Anemia, abdominal mass, wasting
• Left colon
• Change in bowel habits
• Altered blood/mucous
• Obstruction
• Rectum
• Tenesmus
• Hematochezia
• Rectal pain or mass
• Secondaries and general symptoms
• Perforation
• Ascites
• Hepatomegaly
• Jaundice , anorexia
©Dr Winston

12. Examination
• Look for pallor, jaundice, edema, lymph nodes, weight loss
• Abdominal distension due to ? Intestinal obstruction
• Elicit hepatomegaly and or ascites
• DRE for palpable mass, blood on EF, presence of hemorrhoids,
absence of stool
• Examine other systems for fitness of surgery/chemo/radio
©Dr Winston

13. Investigation
• Blood count
• Fecal occult blood (FOBT, FIT)
• Barium enema – apple core deformity
• Colonoscopy/Sigmoidoscopy
• CT abdomen, CT Colography
• MRI pelvis
©Dr Winston

14. Differential diagnosis
• Diverticulosis
• Inflamatory bowel disease – UC or CD
• Dysentery
• Ileus/chronic constipation
• Bowel ischemia
• Infectious colitis (amoebic colitis)
©Dr Winston

15. Treatment
• Mainstay is surgery if tumor is colonic
• Right, extended right colectomy
• Left colectomy
• Large disease in rectum – Neo-adjuvant treatment with chemoradiotherapy
• Surgery for rectal ca
• Local transrectal resections (TEM, TAMIS)
• Anterior or low anterior resection
• Abdomino-perineal resection (APR)
• Adjuvant chemotherapy
• Oxaliplatin, 5 Fluorouracil, Leukovorin, capecitabine
• Second-line chemo – irinotecan, taxanes
• Targeted therapy: bevacizumab
• Palliation
• Local resection, bypass, colostomy
• Irradiation and ? Palliative chemotherapy
• Ascitic drainage, analgesics
©Dr Winston

16. Anatomical basis of
types of colectomy
©Dr Winston

17. Local surgery for small rectal cancer
©Dr Winston

18. Follow-up and surveillance
First 2 years
• CEA levels 3 monthly
• CT abdomen annually
• Colonoscopy annually (with polypectomy)
Subsequent 3 years
• CEA 6 monthly
• Annual CT
• Annual colonoscopy (with polypectomy)
©Dr Winston

19. Screening
Risk Procedure Age Frequency
Low
(no RFs)
FOBT
Colonoscopy
50
50
Yearly
Every 5 years
Moderate – RFs present
(Colon ca in 10 relative, large polyp in colonoscopy)
FOBT
Colonoscopy
45
45
Yearly
Every 3 years
High
(FAP, HNPCC, IBD,)
Colonoscopy 20-40 Yearly
*RFs – risk factors
©Dr Winston

20. Review
• Epidemiology of CRC
• Surgical anatomy of the colon and rectum
• Classification of colorectal tumors
• Risk factors
• Pathology
• Staging
• Clinical presentation and examination
• Investigation
• Differential diagnosis
• Treatment and follow-up
©Dr Winston

21. Thank you