GI - Colorectal cancer Flashcards

Question

Choice of anastomosis after colectomy

Answer 1

Primary anastomosis without temporary proximal diverting ostomy - Uncomplicated cases - Right or extended right hemicolectomy (lower bacteria count) Primary anastomosis with temporary proximal diverting ostomy - Complicated cases: obstruction, perforation, localized peritonitis - Proximal diverting ostomy include loop ileostomy, loop colostomy or end ostomy - Left hemicolectomy (high risk of anastomotic leakage) benefits from proximal diversion to lower complication rate and risk of reoperation for anastomotic leakage No primary anastomosis: - Medically unstable - Diffuse peritonitis - Free perforation

Answer 2

General complications (Early < 30 days) - Surgical site infection - Postoperative ileus Intra-abdominal complications (Immediate) - Anterior resection syndrome: Fecal frequency, urgency, clustering or incontinence - GI: Splenic/ Duodenal/ Pancreatic/ Gastric injury - UG: Ureteral/ Bladder/ Urethral injury Anastomotic complications: - Bleeding: give blood transfusion and correct coagulopathy - Leakage (intraperitoneal/ extraperitoneal): give fluid resuscitation and broad-spectrum IV antibiotics, bowel rest, image-guided percutaneous drainage of abscess, temporary fecal diversion or drainage, resection of the anastomosis - Stricture: observe, finger dilatation for low anastomosis and endoscopic balloon dilatation for high anastomosis - Fistula (Enterocutaneous, rectovaginal, and rectourinary fistula): Enterocutaneous fistula can be managed by conservation; Rectovaginal or rectourinary fistula should be managed with proximal fecal diversion

Answer 3

Lifestyle modifications: - Physical activity * Perform ≥ 150 mins of physical activity per week - Dietary changes * ↑ Intake of dietary fibers (e.g. whole-grains, beans, fruits and vegetables) * ↓ Intake of red and processed meat (e.g. sausage, ham, bacon and luncheon meat) - Avoid alcohol and smoking Surveillance: Stool-based tests - Guaiac-based fecal occult blood test (gFOBT) - Fecal immunochemical test (FIT) - Fecal DNA test Direct visualization tests - Colonoscopy - Flexible sigmoidoscopy - Capsule endoscopy - CT colonography (colonic imaging)

Answer 4

MoA: - detect only human globin and thus do NOT detect upper GI bleeding since the globin is digested during the transit (more specific to lower GI bleeding) - Food with peroxidase activity also do not produce a positive reaction Sampling: - Only 1 stool sample is required for automated analysis - Sensitivity of test decreases with mailing, delayed processing after sampling and exposure to high ambient temperature due to Hb degradation | A

Answer 5

MoA: - Genetic mutations and epigenetic changes acquired during carcinogenesis can be detected in stool from DNA shed by colorectal neoplasm Sampling: - Individuals collect a full stool sample - Optimal interval between screening fecal DNA test is every 3 years

Answer 6

Testing: - 60 cm sigmoidoscopy can reach to splenic flexure and can only identify leftsided colonic lesions - paired with air-contrast barium enema to detect transverse and right-sided colonic lesions Interval: - Recommended every 5 years when performed alone or every 10 years if performed along with FOBT or fecal immunochemical test (FIT) - Follow-up colonoscopy is indicated of multiple or large adenomas (≥ 1.0 cm) and for adenomas with villous histology

Answer 7

Testing: - Definitive test for detection of advanced adenomas and colorectal cancer - Used for screening, diagnostic and therapeutic purposes Test procedures - Aggressive bowel preparation is required - Recommended to screen every 3-6 months for first 3 year - Then every 6 months for 2 years - CEA every 3-6 months

Answer 8

Local tumour extent (T stage) - Depth of tumour penetration Regional nodes (N stage) - Nodal involvement is the single MOST important prognostic factor in CRC - 4 or more involved LN predicts a poor survival - T stage is the single most significant predictor of LN metastasis o T1 stage = 5% o T2 stage = 20% o T3 and 4 stage = > 50% Lymphovascular invasion - Perineural invasion - Grade of differentiation Molecular factors - Mismatch repair deficiency (Mutation in DNA mismatch repair (MMR) gene) - RAS and BRAF mutation Prognosis based on TNM staging: 5-year survival of colon cancer * Stage I = 90% * Stage II = 60 – 80% * Stage III = 60% * Stage IV = 10%

Answer 9

DIfferences: - Transanal access is possible up to 10cm of rectum - Easier to treat with neoadjuvant RT due to paucity of small bowel - Confined to pelvis and presence of sphincter impossible to make wide excision - Proximial to urogenital structures and nerves makes resection more challenging - More difficult to achieve radial margins Principles: - Adequate circumferential margin: distal 2cm margin when TME is performed - Total mesorectal excision (TME) - LN clearance with high ligation of arterial pedicle (IMA) - Sphincter and autonomic nerve preservation

Answer 10

Advatage: - Downstaging by treating local LN - Shrinkage to improve resectability and sphincter sparing - Similar result but significantly less toxicity than post-operative chemotherapy Disadvantage: - Over-treatment of early stage tumours - Impair wound healing - Increase post-operative complications - Pelvic fibrosis

Answer 11

**Local excision = **Radical resection = Anterior resection/ Abdominal perineal resection (APR)** Stage 1 (T1-2, N0, M0): Local excision/ Radical resection with permenant colestomy - Radical resection recommended due to high recurrence risk Stage 2 (T3-4, N0, M0): Neoadjuvant chemoRT + Radical resection Stage 3 (Any T stage + N1, M0): Neoadjuvant chemoRT + Radical resection - Advance resection with TME Stage 4 (Any N and M stage) - Isloated liver or lung met can be resected for cure - Palliation for unresectable: Palliation: - Endoluminal stent - Diverting stoma - Bypass surgery - Local cauterization or laser ablation for bleeding

Answer 12

Tumor factor: - Size - Location from anal verge - Location from anorectal ring - LN metastasis - Invasion in lateral pelvic walls and intra-abdominal organs Patient factor: - Firness for surgery - Pre-surgical anorectal sphincter function - Pelvic anatomy Surgeon factors - Experience - Hospital equipment

Answer 13

Proximal minimum -ve 5cm margin Distal: - Try to maximize sphincter preservation - Failing enough -ve distal margin = convert from sphincter sparing resection to APR - Minimum -ve distal margin in cancer above distal mesorectal margin = 2cm - Minimum -ve dital margin in cancer at or below distal mesorectal margin = 1cm Circumferential radial margin (CRM) = 1cm minimum

Answer 14

Local excision (no TME)  Transanal endoscopic surgery (TES)  Transanal excision (TAE)  Posterior excision Radical exicison (with TME) - Sphincter sparing: Anterior resection (AR)/ Low anterior resection (LAR) - Non-sphincter sparing: abdominal perineal resection, multivisceral resection/ Pelvic exenteration TME: - Trans-abdominally performed with open, laparoscopic, robotic - Dissect endopelvic fascia for complete removal of rectal mesentery (perirectal areolar tissue) - Extent: remove lateral and cricumferential margin of mesorectal envelop to 5cm below distal margin for upper rectal tumour, or to pelvic floor for middle or lower rectal tumour - High ligation of IMA and regional LN dissection - A/w longer survival, lower recurrence, less bleeding, lower risk of damage to pelvic and presacral nerves compared to blunt dissection

Answer 15

Indication: ALL of the following criteria has to be met - Tumours stage = T2 – 4 (Invasive rectal cancer) - Adequate presurgical anorectal sphincter function - Able to achieve clear (negative) margins with local excision Technique: - Anterior resection: Margin and anastomosis above peritoneal reflection - Low anterior resection: Margin and anastomosis below peritoneal reflection, Removal of sigmoid colon and rectum to a level where the distal margin is free of cancer + primary colorectal or coloanal anastomosis +/- proximal diverting ostomy or end colostomy (Hartman) Anastomosis: - Colonic J-pouch reservoir: J shape neorectal reservoir - Side-to-end reservoir: T shape coloanal anastomosis - Transverse coloplasty High risk of leakage Defunctioning stoma: - Temporary divertion with loop ileostomy or loop colostomy - Decreases complication rate and risk of reoperation for anastomotic leakage - Indicated: Low anastomosis, Anatomosis under tension, Intra-operative leak test positive

Answer 16

MoA: - Guaiac testing of stool samples identifies Hb by the presence of a peroxidase reaction which turns the guaiac-impregnated paper blue - Guaiac reagents available on marker includes Hemoccult-SENSA (preferred)/ Hemoccult/ Hemoccult-II/ Hemoccult-R Sample: - Screening by gFOBT should be performed on 3 consecutive stool specimens - Vitamin C should be restricted for at least 3 days prior to sampling (cause FN) - Restrictive diet is NOT necessary as it decreases screening compliance Test performance - Hemoccult SENSA: Sensitivity = 64 – 80%; Specificity = 87 – 90% - Hemoccult II: Sensitivity = 25 – 38%; Specificity = 98 – 99%

Answer 17

Early complications (Early < 30 days) o Stomal bleeding o Stomal necrosis o Stomal retraction o Mucocutaneous separation o Skin irritation and dermatitis (most common in end and loop ileostomy due to highoutput and high alkaline enzymatic effluent) Late complications (Late > 30 days) o Parastomal hernia o Stomal prolapse o Stomal stenosis

GI - Colorectal cancer Flashcards

(44 cards)