Colorectal neoplasms

COLORECTAL

NEOPLASMS

By

Dr. Abdul QadeerMBBS; FCPS; FICS

Assistant Professor in Surgery

King Faisal University College of Medicine

Kingdom of Saudi Arabia

OBJECTIVES

1. Clinical anatomy of colon & rectum

2. Physiology of colon

3. Colorectal polyps

4. Adenoma-carcinoma sequence

5. Classification of colorectal cancer

6. Signs & symptoms

7. Causes

8. Pathogenesis

OBJECTIVES (CONTD….)

9. Diagnosis

10. Prevention: Lifestyle, medication, screening

11. Management: surgery, chemotherapy,

radiation, palliative care

12. Prognosis

13. Follow-up

14. Epidemiology

1. CLINICAL ANATOMY OF COLON & RECTUM

Large intestine (Colon & rectum) begins at ileo-caecal valve and extends up to the anus

Consists of:

1. Caecum (with appendix attached),

2. Ascending colon,

3. Hepatic flexure,

4. Transverse colon with attached greater omentum,

5. Splenic flexure,

6. Descending colon,

7. Sigmoid colon and

8. Rectum (begins at sacral promontry)

Transverse and sigmoid colon are mobile

Ascending, descending colon and rectum are

fixed

Apendices epiploicae

Taenia coli

Haustrations

ANATOMICAL RELATIONS

Posterior relations of cecum & ascending

colon are:

1. Right ureter

2. Right gonadal vessels

3. Duodenum

Posterior relations of left colon are:

1. Left ureter

2. Left gonadal vessels

3. Tail of pancreas

Rectum is 12-18 cm long in adults, encircled

by the puborectalis muscle, creating an

anorectal ring (120o)

It has three curves, 2 on right side and 1 on

left side

Theses curves make semicircular folds

(Houston’s valves) from inside

ANATOMICAL RELATIONS OF THE RECTUM

Its upper 1/3rd = peritoneum anteriorly +

laterally

Its middle 1/3rd = peritoneum anteriorly

Its lower 1/3rd = no peritoneum covering

Anteriorly = prostate/vagina separated by the

Denonvilliers’ fascia

Posteriorly = sacrum & coccyx separated by

Waldeyer’s fascia

BLOOD SUPPLY OF LARGE INTESTINE

Branches of:

a) Superior and inferior mesenteric arteries

b) Marginal artery of Drummond

Watershed area at the splenic flexure

renders it vulnerable to ischemic colitis

Venous and lymphatic drainage of colon

follow the arterial supply

Venous blood is drained into the portal

system

BLOOD SUPPLY OF RECTUM

1. Superior rectal artery: a direct continuation of inferior mesenteric artery

2. Middle rectal artery: on each side from the internal iliac artery

3. Inferior rectal artery: on each side from the internal iliac artery

4. Upper ½: superior hemorrhoidal veins superior rectal vein inferior mesenteric vein

5. Middle rectal veins (unimportant) occasionally exist

LYMPHATIC DRAINAGE OF RECTUM

Follow the upward route of superior rectal

vessels (the inferior mesenteric vessels),

hence important for surgical clearance in

malignancy

If it is blocked, then reverse flow may occur

to the nodes along with middle rectal vessels

or the inguinal region via inferior rectal

vessels

NERVE SUPPLY OF THE LARGE INTESTINE

Sympathetic nerves via splanchnic nerves

surrounding the superior and inferior

mesenteric arteries

Parasympathetic nerves via vagus and pelvic

splanchnic (S2-4) nerves

2. PYHSIOLOGY OF LARGE INTESTINE

Absorption of water is the principal function

of the colon

Out of 1000 ml of ileal contents, 150-250 is

excreted as feces.

Sodium is actively absorbed

Chloride and water are passively absorbed

by the sodium pump

A tiny amount of glucose, fatty acids, amino

acids and vitamins are also absorbed

Dietary fiber is fermented by normal colonic

microflora (anaerobes e.g. bacteroides and

bifidobacteria) producing short chain fatty

acids (SCFAs) e.g. butyrate which provides

fuel for colonic mucosa

Diversion of the fecal stream e.g. loop

ileostomy may cause diversion colitis

COLONIC MOTILITY

It is variable

Fecal residue reaches the caecum 4 hours,

and rectum 24 hours after meals

Some residue may still be passed after 4

days through the rectum

3. CLASSIFICATION OF INTESTINAL POLYPS

NO

.

TYPE OF

POLYP

EXAMPLE

1. Inflammatory Pseudopolyps in ulcerative colitis

2. Metaplastic Metaplastic or hyperplastic polyps

3. Hamartomatous Peutz-Jeghers polyp, Juvenile polyp

4. Neoplastic A. Adenoma i. Tubular

ii. Tubulovillous

iii. Villous

B. Adenocarcinoma

C. Carcinoid tumor

4. ADENOMA-CARCINOMA SEQUENCE

Colorectal cancer arises in a stepwise

progression from adenomas in which

increasing dysplasia in the adenoma is due

to an accumulation of genetic abnormalities.

This is known as adenoma-carcinoma

sequence

5. CLASSIFICATION OF COLORECTAL CANCER

Mostly adenocarcinomas

Rarely, carcinoid tumor, leiomyosarcomas

etc.

Colorectal cancers are staged by:

Duke’s staging

Astler-Coller staging

TNM staging

It is also graded into low (well-differentiated),

average and high (undifferentiated)

histological grades

DUKE’S STAGING

STAG

E

DEFINITION PROGNOSIS

A The growth limited to the intestinal

wall

Excellent (90% year survival rate

B The growth is extended to the extra-

intestinal tissues

No metastasis to the regional lymph

nodes

Reasonable (70% year survival

rate)

C There are secondary deposits in the

regional lymph nodes

C1: local pararectal lymph nodes only

involved

C2: lymph nodes along the vascular

trunks are involved e.g. inf. Mesenteric

group

Poor (40% year survival rate)

D Distant metastasis e.g. hepatic

TNM STAGING

T N M

T1: tumor invasion through the

muscularis mucosa but not

into the muscularis propria

N0:No lymph node

involvement

M0:No distant metastasis

T2: Tumor invasion into but not

through the muscularis

propria

N1:Between one & three lymph

nodes involvement

M1:Distant metastasis

T3: Tumor invasion through the

muscularis propria but not

through the serosa or

mesorectal fascia

N2:Four or more lymph nodes

involvement

T4: Tumor invasion through the

serosa or mesorectal fascia

6. SIGNS & SYMPTOMS

Age: usually above 55

bleeding per rectum

Sense of incomplete defecation:

tenesmus, spurious diarrhea, bloody slime

Alteration in bowel habit: early morning

bloody diarrhea

Pain: a late symptom

Weight loss: suggests liver metastasis

7. ETIOLOGY

Adenoma-carcinoma sequence

Mutation of APC gene, K-ras gene, p53 gene

Diet: red meat, animal fat. Fiber is protective

Smoking

Alcohol

Long-standing ulcerative colitis & Crohn’sdisease

After cholecystectomy and ureterosigmoidostomy?

8. PATHOGENESIS

Macroscopically: 4 forms

1. Annular

2. Tubular

3. Ulcerative

4. Cauliflower

Microscopically:

1. Adenocarcinoma commonly

2. Lymphoma, GIST (leiomyosarcoma) rarely

SPREAD OF COLORECTAL CARCINOMA

1. Direct spread: longitudinal, transverse or

radial

2. Lymphatic spread

3. Hematogenous spread: commonly to the

liver, lungs, brian, bone, ovary, kidney are

rare

4. Transcoelomic spread: other structures

within the peritoneum e.g. omentum

9. DIAGNOSIS / INVESTIGATIONS

Screening: testing for fecal occult blood

followed by colonoscopy in 60-69 aged

people. A guaiac-based test is used which

detects the peroxidase like activity of fecal

hematin.

Endoscopy: fiberoptic, flexible

sigmoidoscopy / colonoscopy ± biopsy

Radiology: double-contrast barium enema

may show a filling defect. CT scan of

abdomen / chest

CONTRAST RADIOGRAPHY (APPLE-CORE

APPEARANCE)

10. PREVENTION

Change the dietary habits

Quit smoking and alcohol

Early diagnosis of intestinal polyps

11. MANAGEMENT (SURGERY)

Pre-operative preparation±

Prevention of thromboembolism by anti-

embolic stockings or s/c LMW heparin

Operations for colon:

1. Right hemicolectomy

2. Extended right hemicolectomy

3. Left hemicolectomy

4. Emergency surgery e.g. Hartmann’s

procedure

MANAGEMENT (SURGERY)

Operations for rectum:

1. Anterior resection

2. Abdomino-perineal excision of the rectum

3. Endoluminal stenting

4. Palliative colostomy/laser

5. Pelvic exenteration (Brunschwig’s

operation)

6. Liver resection

MANAGEMENT (CHEMOTHERAPY)

May be used combined with radiotherapy to

make the advanced tumor operable

5-FU as adjuvant therapy in node-positive

disease (Duke’s stage C/N1,2). It may be

combined with oxaliplatin

MANAGEMENT (RADIOTHERAPY)

Palliative irradiation for inoperable, painful

tumors

Brachyradiotherapy

12. PROGNOSIS (5-YEAR SURVIVAL RATE)

Overall 5-year survival for colorectal cancer

is 50%

Duke’s stage A: by surgical resection alone,

90%

Tumor spread beyond the bowel wall: 60-

70%

Tumor with lymph node metastasis: 30%

Metastatic disease: 10%

13. FOLLOW-UP

Surveillance colonoscopy

Regular imaging of liver (US, CTS) for

metastasis

Measurement of CEA

14. EPIDEMIOLOGY

In UK, colorectal cancer is second most

cause of cancer death

About 35000 patients are diagnosed with

colorectal cancer every year in UK; 1/3rd of

rectum and 2/3rd of colon

M:F = same

Less frequent in developing countries than in

industrialized countries