Transcript
CA COLONBy
Dr. MANISH DUTT[PG 1st yr. ]
Dept. of RADIATION ONCOLOGY
• ANATOMY• EPIDEMIOLOGY• PRESENTATION• PATHOLOGY• DIAGNOSTIC WORKUP• STAGING• SCREENING
ANATOMY ileocecal valve to the anus, approximately 150 cm in length. increaseddiameter, the presence of haustra[small pouches caused by sacculation],tenia coli.[condensationsof longitudinal muscle fibers]
Epicolic node-adj to L.IParacolic nodes-on marginal vesselsIntermediate nodes-along major br. Of SMAPrincipal nodes-origin of vessel at aorta
EPIDEMIOLOGY• 3rd mc cancer in men ,2nd in women[ app. 10% of
all cancers]• 2nd mcc of cancer mortality• 55% of cases in more developed regions• highest rates in Australia/New Zealand (ASR 44.8
and 32.2 per 100,000 in men and women, and the lowest in Western Africa (4.5 and 3.8 per 100,000]
• highest mortality in Central and Eastern Europe (20.3 per 100,000 for men, 11.7 per 100,000 for women), and the lowest in Western Africa (3.5 and 3.0)
• Ashkenazi jews, African americans at higher risk
INDIAN STATS• In India, annual incidence rates (AARs) for colon ca in
men is 4.4 , in women is 3.9 per 100000.• Colon cancer ranks 8th in men 9th among women• In the 2013 report, the highest AAR in men for CRCs was
recorded in Thiruvananthapuram (4.1) followed by Banglore (3.9) and Mumbai (3.7) . • The highest AAR in women for CRCs was recorded in
Nagaland (5.2
ETIOLOGY- ENVIRONMENTAL • Age and gender: Older men • Ulcerative colitis• Ethnicity: The African American• High-caloric diet & obesity• High red meat consumption [sausage]• High saturated fats • Excess alcohol consumption[ folate
metab. And acetaldehyde]• Cigarette smoking • Sedentary lifestyle • Diabetes
protective High-fiber diet[dilute faecal
carcinogens, dec colon transit time]
Antioxidant vitamins Fresh fruit/vegetables NSAIDS & COX-2 inhibitors[ in lynch synd.] Coffee High calcium[ binds bile acids] High Magnesium Vit D & bisphosphonates[ inhibit
cell proliferatn, inc. apoptosis]
Genetic factors• FAP[1% of all CRC]• AD germline mutation in the APC gene on chromosome 5q21• 100% risk • 100-1000 colonic polyps in teens• Extracolonic manifestations –(congenital hypertrophy of the retinal pigment epithelium,
desmoid tumors)• Turcot syndrome (glioma-polyposis) germline APC mutation or mutations in (MMR) genes
(MLH1 and PMS2).• Attenuated FAP
• Lynch syndrome(HNPCC)- is an autosomal dominant condition and is caused by a defect in one of the MMR genes, namelyMLH1, MSH2, hMSH6, or PMS2. The peculiarity of Lynch
• early average age of onset of colorectal malignancy and the predominance of right-sided colonic lesions. Breast, thyroid, and gynaecological cancers can co-exist.
Pathology-MULTI STEP MODELS OF COLORECTALTUMORIGENESIS
STAGING
• Pathologic examination should include---.• Tumour grade• Depth of penetration• Number of positive lymph nodes and number of lymph nodes evaluated (a minimum of12 lymph nodes should be evaluated).• Lymphovascular invasion• Perineural invasion• Extranodal tumour deposits• Status of proximal, distal, and radial (circumferential) margins
CLINICAL PRESENTATION• HISTORY--• lower GI bleeding,• change in bowel habits, abdominal pain, weight loss, • Loss of Appetite &weakness, obstructive symptoms[usually in the sigmoid or
left colon]• Physical examination may reveal a palpable mass,• bright blood per rectum (usually left-sided colon cancers or rectal cancer) • melena (right-sided colon cancers]• Adenopathy, hepatomegaly, jaundice,or even pulmonary signs may be
present with metastatic disease• Laboratory values may reflect iron-deficiency anemia, electrolyte• derangements, and liver function abnormalities
Diagnostic workup
Rigid sigmoidoscopy instruments limit evaluation to the distal 25 cm of the colon, whereas flexible sigmoidoscopy permits evaluation of the distal 55–60 cm of the colon.
Complete colonoscopy (essential) should be attempted in all patients before or after surgery to exclude synchronous lesions or polyps
SCREENING• The average-risk patient is defined as a man or woman above the age of
50 without personal or family history of adenomatous polyps or CRC and absence of any occult or acute GI bleeding.• Following can be used for screening• FOBT• digital rectal examination• COLONOSCOPY[Optical colonoscopy is currently the most sensitive
method for screening. Advantages include direct visualization, with the ability to remove polyps (with rate-limiting factors of size and anatomic location) and to obtain biopsies• SIGMOIDOSCOPY
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