COLON AND RECTUM

ANATOMI DAN FISIOLOGI

cecum, right colon, and midtransverse colon MIDGUT ORIGIN superior mesenteric artery and vein.

distal transverse colon, splenic flexure, descending colon, and sigmoid colon HINDGUT ORIGIN inferior mesenteric artery and vein

Invasion to muscularis mucosa Lymphatic drainage at lamina propia (ikuti jalur pembuluh darah) metastasis.

major functions of the colon : Absorption Storage Propulsion Digestion

rectum 12 to 15 cm, from the rectosigmoid junction, (marked by the fusion of the taenia) to the anal canal, (marked by the passage of the bowel into the pelvic floor musculature)

VALVES OF HOUSTON

MALIGNANT DISEASE

second leading cause of death 15% of all malignancies

30% rectum 28% sigmoid 9% descending colon 11% transverse colon 9% ascending colon 13% in the cecum.

SCREENING AND SURVEILANCE For colorectal cancer, surveillance : patients

with IBD, family cancer syndromes, APC disorders, and a previous history of colorectal cancer or colorectal adenomas.

The presentation of large-bowel malignancy :1. insidious onset of chronic symptoms (77-

92%): bleeding2. acute onset of intestinal obstruction (6-

16%) : change in bowel habit.3. and acute perforation with local or diffuse

peritonitis (2–7%).

STAGING FOR : predicting outcomes, selecting therapies, and

comparing therapies invasive cancer penetrate through the

muscularis mucosa. Dukes :

Dukes’ A lesions are those in which the depth of penetration of the primary tumor is confined to the bowel wall.

Dukes’ B lesions have primary tumor penetration through the full thickness of the bowel to include serosa or fat.

Dukes’ C lesions have local (C1) or regional (C2) nodal involvement

distant spread (D) outside the resected specimen. TNM to incorporate findings at laparotomy. Correlate

to the stages of Dukes’ C; stage 4 is the equivalent of Dukes’ D

(AJCC) : low grade (well and moderately

differentiated) and high grade (poorly and

undifferentiated) DNA in cells.

Diploidy good prognoses; aneuploidy poor prognoses.

(CEA) poorer prognosis.

PREOPERATIVE STAGING FOR COLORECTAL CANCER

Cancer of the Cecum, Ascending Colon, or Hepatic Flexureright hemicolectomy. involving the hepatic flexure “an extended right

hemicolectomy.” Cancer of the Transverse Colon

transverse colon is resected, including either the hepatic or splenic flexure.

Cancer of the Splenic Flexureremoval of the distal half of the transverse colon and the descending colon.

Cancer of the Sigmoid Colonremoval of the sigmoid colon.

Subtotal colectomy synchronous lesions at different sites.

If synchronous lesions in the same anatomic region a conventional resection may be performed.

CANCER OF THE RECTUM

abdominal perineal resection, which removes the whole rectum and anus.

with and without radiation

Cancer Arising in a Colon Polyp There is now a general consensus

that most colon cancers arise from preexisting polyps.

The lifetime risk of an adenoma transforming into a malignancy is estimated to be 5% to 10%,

time for transforming is estimated to be 5 to 15 years.

no potential for metastases.

metastases : liver, the lung, the bone, and the brain

Patients with disseminated disease beyond the scope of surgical resection are eligible for chemotherapy.

POLYPOSIS COLI SYNDROMES

Familial Adenomatous Polyposis inherited, non–sex-linked, progressive development of hundreds of polyps. The mutated gene is called the APC gene. The condition is characterized by the

development of hundreds to thousands of colonic adenomatous polyps and an

extreme risk of colon cancer. at a mean age of 16 years, have cancer by age 21, 50% by age 39, and 90% by the

age of 45 years.

POLYPOSIS COLI SYNDROMES

Hereditary Nonpolyposis Coli Syndromes I and II (HNPCC)

an autosomal-dominant inherited high risk of colon cancer. 45 years Screening not only should be directed at the

colon but also at the pancreas, breast, cervix, ovary, and bladder.

Colonoscopic every year until 30 years of age and annually thereafter.