Colorectal Carcinoma And Polyps

Colorectal Carcinoma and Polyps SENG Jingjing Department of General Surgery

Surgical Anatomy

•Large intestine •Cecum and the ileocecal valve

•Ascending colon and hepatic flexure •Transverse colon •Splenic flexure

•Descending colon •Sigmoid colon •Rectum •Anus

Average Length: 135-150cm

The function of the colon •Water absorption •Evacuation of fecal waste

Three Gross Characteristic •Taeniae coli •Haustra •Appendices epiploicae

Taeniae coli The outer longitudinal muscular coat is concentrated into three separate longitudinal scrips

Haustra of the colon Which are sacculations or protrusions of the bowel wall between the taeniae

Appendices epiploicae Which are extensions of peritoneal fat

Their appearance on simple radiographs of the abdomen is characteristic and often allows distinction of the colon from the small intestine

Blood supply of the colon

Ileocolic,right colic middle colic branches of the superior mesenteric artery the cecum assending colon hepatic flexure and proximal portion of the transverse colon

The inferior mesenteric artery distal transverse colon, splenic flexure descending colon

The left colic artery and branches of the sigmoid and superior hemorrhoidal vessels ->sigmoid

The middle hemorrhoidal and the inferior hemorrhoidal arteries ->rectum

Colorectal Carcinoma and Polyps

Introduction Cancer of the colon and rectum is the second most common malignancy in men and the third most common in women in the western world

Adenocarcinomas majority Carcinoid tumour Others rare • Lymphoma • Squamous carcinomas ---anus and canal skin

Polyp nasal polyps endometrial polyps polyps of peutzJehger syndrome

Colorectal Polyps

•Polys are a common finding in the large bowel •Their great importance is in relation to malignant change

•Most colorectal polyps are adenomas and all of these have potential for malignant change

Pathological Classification of Colorectal Polyps

Neoplasms Adenomas Early Carcinomas Lymphomas Leiomyomas and leiomyosarcomas Lipomas and liposarcomas Carinoid Tumors Hyperplasias Metaplastic mucosal Polyps Lymphoid Aggregations Hamartomas Angiomas Juvenile Polyps Inflammatory Polyps

Adenomatous polyps(adenomas)

Malignant potential •Adenomas are clinically important because they undergo malignant change

Histological Patterns •Tubular adenomas •Villous adenomas •Tubulo-villous adenomas

Familial adenomatous polyposis(FAP)

•When multiple tububar adenomas occur throughout the large bowel ,in this inherited condittion there is a very high risk of early malignant transformation

Symptoms and signs of coloretal polyps

Early stages: no symptoms

Rectal bleeding Anaemia Tenesmus Prolapse

Diagnosis of colorectal polyps

Colonoscopy and Biopsy Barium Enema Examination

Management •Remove the polyps •Resect the bowel

Adenocarcinoma of Colon and Rectum

Epidemiology

•The diease is rare before the age of 40,but it is common after the age of 60

•There is little difference in incidence between the sexes

•First degree relatives of patients with colorectal cancer have a twofold increased risk of developing this malignancy

•It is a disease of developed countries

•Western lowfibre,high-fat diet is the related factor

Metastasis •Lymphatic spread •The bloodstream spread-liver

Presentation

•The right colon is larger in diameter and the faecal stream more fluid .therofore tumors of the right colon rarely cause obstruction unless the ileo-caecal valve is involved

•Occult bleeding from the tumor surface commonly causes iron deficiency anaemia and these these patients typically present with anaemia and a polyable mass in the right iliac fossa

• The stool in the left colon is more solid than on the right and so left-sided cancers usually present with a change in bowel habit or precipitate an emergency admission to hospital with large bowel obstruction which may be partial or complete

•Blood is often visible in the stool and the character of the blood and its mixing with stool depends on how far the lesion is from the anus

•Lesions(carcinomas or polyps) in the lower two-thirds of the rectum may be preceired as a mass of faeces. This stimulates a persistent defaecation response causing the symptom of tenesmus

•A cancer eroding through the bowel wall may stimulate a vigorous local inflammatory process resulting in a pericolic abscess.

•This occurs in the rectosigmoid area and usually presents with left iliac fossa pain and tenderness and a swinging fever. Differential diagnosis is acute diverticulitis or divertialar

•A carcinoma anywhere in the colon may peritonitis . Occasionally a malignant fistula occurs into stomach bladder,uterus,vagina or to the skin

Clinical Signs

Rectal Examination •Carcinomas occur in the lowest 12cm of the large bowel and can be reached with an examining finger.

General Examination •Anaemia •Obvious weight loss •Supraclavicular node enlargement

Abdominal examination •Colonic mass •Liver enlargement due to metastases or ascites

Investigation •Proctoscopy •Sigmoidscopy •Colonoscopy •Barium enema •Ultrasound or CT scanning

•Many patients,especially the eldly,presents as emergencies with complete large bowel obstruction ,often in the sigmiod colon or rectosigmoid junction

Differential diagnosis

• Benign tumours • Ovarian or uterine tumours • Extension from carcinoma of the prostate or cervix • Diverticular disease • Endometriosis • Lymphogranuloma inguinale • Amoebic granuloma • faeces

MANAGEMENT

•Surgical resection is the main treatment for colorectal carcinoma

Rectum cancer • Surgery depends upon the distance of the tumour from the anal verge

• Uppers-third tumours can be resected with restorative anastomosis between the sigmoid colon and the lower rectum(anterior resection)

• Lower-third tumours, less than 5cm from the anal verge, are usually treated by abdomino-perineal excision of the rectum,with a terminal colostomy.

• Mid-third rectal tumours can usually be treated by anterior resection,provided that satisfactory distal cleanrance can be obtained.The operation is easier in the female ,where the wider pelvis facilitates dissection.

•Adjuvant radiotherapy and chemotherapy are sometimes used but benefits are as yet equivocal

Staging

Dukes’classification

Dukes’A •Tumour confined to the bowel wall with no extension in to the extrarectal or extracolic tissues and no lymph node metastases

Dukes’B •Tumour spread confined to the extrarectal or extracolic tissues by direct continuity but without lymph node metastases

Dukes’C •lymph node metastases

•C1 in which only a few nodes are involved near the primary growth ,leaving proximal nodes free from metastases

•C2 in which there is a continuous string of involved lymph nodes up to the proximal limit of resection

Dukes’D •This is a later addition to duke’s staging ,based on clinical rather than pathological evidence.

•These patients are found at operation to have distant metastases or such extensive local or nodal spread that the lesion is surgically incurable whatever the pathological staging

5-year survival rates •Dukes’A •Dukes’B •Dukes’C1 •Dukes’C2

97% 80% 65% 35%

Complications of large bowel surgery

Early Complications

•Wound infections •Intra-abdominal abscess •Systemic sepsis and multi-organ failure

•Anastomotic leak breakdown •Inadvertent damage to other organs •Stoma problems

Later complications

Diarrhoea •Division of pelvic parasympathetic nerves small bowel obstruction

Bowel Cleaning Techniques 1 、 Withdrawal of solid foods 2 、 Purgation 3 、 Enemas and distal bowel washouts.