Contents
Introduction
Colorectal cancer (CRC), also known as bowel cancer and colon cancer, is the development of cancer from the colon or rectum (parts of the large intestine).
- #2 M/C cancer
- M/C GI cancer
Etiology
- DIET
- ↑ Risk: Red meat, saturated fat
- ↑ Cholesterol → ↑ Bile acid (cocarcinogen)
- ↓ Risk: High fibre diet, calcium, Vitamin A, C, E & Zn
- ↑ Risk: Red meat, saturated fat
- GENETIC
- Family history
- Common in people with,
- Adenoma colon
- Familial adenomatous polyposis (FAP)
- Gardner’s syndrome
- Turcot’s syndrome
- IBD (Ulcerative colitis/Crohn’s disease)
- Alcohol & cigarette smoking
- HNCC (Hereditary nonpolyposis colonic cancer)
- Radiation
- OTHER TREATMENTS:
- After cholecystectomy & ileal resection
- Ureterosigmoidostomy
- Acromegaly
Pathophysiology


Spread:
- LOCAL SPREAD
- Circumferential spread
- Surrounding viscera:
- Liver, stomach, kidney, spleen, diaphragm, mesentery, stomach, pancreas
- Bladder
- Obstruct ureter → Hydronephrosis
- Peritoneum
- Peritonitis/pericolic abscess/faecal fistula
- Psoas muscle
- Ureter, ovary, uterus
- Colovesical/colovaginal fistula
- LYMPHATIC SPREAD
- Upward spread
- Pericolic, epicolic, intermediate & principal group of lymph nodes
- HEMATOGENOUS SPREAD
- Liver (34%)
- Lungs (22%)
- Adrenals (11%)
- Rarely: Other sites of secondary metastasis including brain
- PERITONEAL DISSEMINATION
Classification
Aetiological classification:
- NON HEREDITARY COLON CANCER
- Sporadic colon cancer (60%)
- Familial colon cancer (30%)
- HEREDITARY COLON CANCER
- FAP
- HNCC
- Peutz Jeghers syndrome
- Cronkite-Canada syndrome
- Juvenile polyposis syndrome
Anatomical classification:
- Synchronous
- de novo multiple primary carcinomas in different parts at the same time
- Metachronous
- growth in different parts in different periods
- Annular (stenosing) type
- Ulcerative type
- Cauliflower (proliferative) type
Presentation
- Pericolic abscess/obstruction/perforation/peritonitis
- Secondaries:
- Multiple umbilicated liver secondaries. rectovesical secondaries, palpable left supraclavicular lymph nodes
Right-sided (Ascending colon) location
- Loss of weight & appetite
- Anaemia
- Abdominal discomfort
- Mass per abdomen
- Other presentations:
- Acute intestinal obstruction
- Acute appendicitis
- Intussusception with intestinal obstruction
Left-sided (Descending colon-sigmoid) location
- Dark-red mixed stools ± clots
- Bloating & flatulence
- ↑ Bowel frequency
Rectal region
- Bleeding (Earliest & M/C symptom)
- Tenesmus
- Distressing straining to empty bowels without resultant evacuation
- Spurious diarrhoea
- Often with bloody slime (flatus + blood-stained mucus)
- Altered bowel habits (alternating constipation & diarrhoea)
- Early-morning bloody diarrhoea
- Use of aperient
- Colicky pain (Late symptom)
- Severe (if erodes prostate/bladder)
- When cancer invades sacral plexus,
- Radiation to back or sciatica
- Subacute/chronic intestinal obstruction
- Other presentations:
- Bladder symptoms
Closed-loop obstruction (Transverse Colon)
- Enormously dilated right colon:
- Stercoral ulcer
- Perforation
- Faecal peritonitis
Complications
- LOCAL COMPLICATIONS:
- Intestinal obstruction
- Closed loop obstruction
- Perforation & peritonitis
- Vesicocolic Fistula
- Invasion of ureter
- Perocolic abscess
Diagnosis
- Digital rectal examination
- Flexible sigmoidoscopy
- Identify adenoma
- Colonoscopy (M/accurate & complete investigation)
- Biopsy, polypectomy, control of bleeding, stricture dilation
Lab studies:
- Faecal occult blood test (FOBT)
- Nonspecific test for peroxidase in Hb
- ↑ CEA (Chorioembryonic antigen)
- Nonspecific test for cell-surface glycoprotein for cell-adhesion
- > 5 ng/ml (SIGNIFICANT)
- Normal: < 2.5 ng/ml
- Also found in:
- Pancreatic, gastric, lung, breast carcinomas
- Nonspecific test for cell-surface glycoprotein for cell-adhesion
- Routine blood test
- Hb%, PCV, hematocrit, ESR
- Stool examination
- Occult blood
- LFT
- Alkaline phosphatase, SGPT
Histopathology (Biopsy):




Imaging:
- CT Colonography (Virtual Colonoscopy)
- Barium enema
- Irregular filling defect
- Apple core lesion (left-sided)
- Constriction of lumen (like an apple core after being eaten)
- USG
- Secondaries in liver, peritoneum, lymph node status, retrovesical secondaries


Modified Duke’s Classification
- Growth up to submucosa (rectal wall)
- Growth up to submucosa + extra rectal tissue
- B1: Invading muscularis mucosa
- B2: Invading into/through serosa
- Lymph node secondaries
- Distant metastasis (liver, lungs, bone, brain)
TNM staging
Histological classification
- Low-grade
- Average-grade
- High-grade
Differential diagnosis:
- Ileocaecal TB
- Appendicular mass
- Actinomycosis
- Ectopic kidney
- Mesenteric lymph nodes
- Ovarian tumour (Females)
- Retroperitoneal tumour
- Amoeoboma
Management
Right-sided CRC:
- Early growth:
- Right radical hemicolectomy + ileo-transverse anastomosis
- Inoperable growth:
- (Bypass surgery) ileo-transverse anastomosis
Transverse colon growth:
- Extended right hemicolectomy
Left-sided CRC:
- Early growth:
- Left radical hemicolectomy
- Stenosing type of growth
- 3 stage operation:
- Colostomy
- Proper procedure
- Colostomy closure
- 3 stage operation:
- With obstruction:
- Resection of tumour
- Saline lavage
- Catheterization
- Primary anastomosis
- Multiple synchronous primaries:
- Total abdominal colectomy + ileorectal anastomosis
- Liver secondaries:
- Segmental hepatic resection
- Hhemihepatectomy
- Metastasectomy
- Owen Wangensteen’s Second-look Surgery
Adjuvant therapy:
- CHEMOTHERAPY
- Indications:
- Positive Nodes
- T4-lesions
- Hematogenous spread
- Signet type cell
- Poorly differentiated tumour/aneuploidy
- CEA level changes
- Regimes:
- FOLFOX regimen (Treatment of choice)
- Folinic acid (LV)/5FU/Oxaliplatin
- 5FU (fluorouracil) + folinic acid (leucovorin/LV)
- Levamisole + 5FU
- FOLFOX regimen (Treatment of choice)
- Indications:
- EGFR & VEGF blockers
- In combination with chemotherapy
- Cetuximab (EGFR blocker) & bevacizumab (VEGF blocker)
- RADIOTHERAPY
- Colorectal cancer is radioresistant
- Indications:
- Locally advanced tumour
- Inoperable recurrent tumour
Follow-up:
- Once 3-6 months for 3 years


Summary
Final words