excerpt: >simtec intro lecture
the purpose of this presentation is to introduce..
COLON CANCEREpidemiology•2nd most common cause of cancer mortality•Lifetime risk is about 1 in 17•Industrialized nations have the highest risksoSouth America and China are among the lowest•Blacks > Whites > Asians > Hisp > NA•M > F (slightly)•Incidence increases after age 50 (90%)•80% are sporadicRisk factors•DietoRed meat and animal fatoFolate, fiber, calcium, selenium, fruits and vegetables•Smoking and alcohol•IBD•Hereditary syndromes•Previous carcinoma•Polyps•Family history•S. Bovisbactermia?protective124
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AnatomyLocationAdenoma-Carcinoma Sequence•Larger adenomas harbor cancer more often•Residual benign tissue found in most cancer specimens•Benign polyps have been observed to become cancer•Adenomas occur more frequently in cancer patients•Adenoma patients have increased lifetime risk of dev. cancer•Removal of polyps decreases risk•Populations with cancer have high prevalence of polyps•FAP 100% cancer•Peak incidence of adenomas is 50; peak incidence of cancer is60 suggesting 10-year time span125
Polyps•MorphologyoTubular, villous, tubulovillousRisk of malignancy; 5% - tubular, 22% - tubulovillous, 40% - villousoPedunculated, flat (sessile)Sessile polyp with cancer has 10% chance of lymph node metastasis•Sizeoooo0.6 – 1.5 cm = 2% chance of cancer1.6 to 2.5 = 19% chance of cancer2.6 to 3.5 = 43% chance of cancer>3.5 cm = 76% chance of cancer•Hyperplastic polypsoMost commono90% are less than 3mmoConsidered to have no malignant potentialoAdenomatous changes have been found so polyps should be excisedHaggitts:Applies only to pedunculated polyps•Level 0 – in situ•Level 1 – head of polyp•Level 2 – neck•Level 3 – stalk•Level 4 – submucosa••Any sessile polyp is Level 4Excision of Level 1-3 with 2mm margin andNO poor prognostic indicator is sufficienttreatmentFamilial Adenomatous Polyposis•Autosomal dominant•Defect in APC gene•Hundreds to thousands of polyps•100% cancer conversion rate – avg age 42•Colectomies usually deferred until adulthood•Colectomy with IRA or RPC with lifelongrectal/pouch surveillance•Phenotypic variantsoGardners, Turcots, attenuated126
HNPCC•Lynch I syndrome•Autosomal dominant•Mismatch repair genes altered•85% cancer penetrance•Rapid progression to cancer•Limited number of adenomas usually proximal to splenic flexure•Lynch II – extracolonic manifestationsoUsually endometrial cancerAdenoma-Carcinoma SequenceSigns & Symptoms•Bleeding, abdominal pain, change in bowel habits, anorexia, wt loss, nausea, vomiting,fatigue, anemiaoLeft sided more likely to obstructoProximal cancers have occult bleeding•Pelvic pain, tenesmus in rectal ca•RUQ pain, hepatomegaly, ascites, lymphadenopathy in metastatic disease•Virchow’s node, Blumers shelf, Sister Mary Joseph nodeWork-up•Labs – CBC, LFTs, CEA•DetectionoColonoscopyoDouble contrast BEoVirtual colonoscopy•StagingoCXRoCT/MRI127
oPET - good for extrahepatic metsoIntra-op ultrasound – best evaluation of liverDukesStagingSurgical Issues•Bowel Prep•Perioperative intravenous antibiotics•Midline incision or laparoscopy•ExplorationoExtent of tumoroLiver•Oncologic resection128
•oNo-touch techniqueAnastomosisSurgical Resection•Obstructing canceroHartmans40% morbidity of colostomy closureoOn-table lavage with primary anas.Low leak rateoSubtotal colectomy with IRAaddresses risk of proximal tumorsPerforated canceroPoor prognosisoAssume all adhesions are malignanto20% carcinomatosis risk•Polyp Treatment129