Colonic Polyps & Carcinoma Flashcards
What are the histological types of colonic polyps?
LOW MALIGNANT POTENTIAL
- inflammatory polyps (UC)
- mucosal/submucosal polyps
- hyperplastic polyps -> most common (rectosigmoid)
- hemartomatous polyps (throughout GIT)
MODERATE MALIGNANT POTENTIAL
- serrated polyps -> sessile (>5mm in proximal colon)
- > traditional adenoma (rectosigmoid)
HIGH MALIGNANT POTENTIAL
- adenomatous polyps -> tubular (<5% malignant)
- > tubulo-villous (20% malignant)
- > villous: in rectum (50% malignant)
What are the clinical features of colonic polyps?
- asymptomatic usually
- hematochezia
- change in bowel habits
- mucus in stool
- pallor
What are the variants of adenomatous polyposis syndromes?
FAMILIAL ADENOMATOUS POLYPOSIS (more than 100 polyps)
- Gardener Syndrome
- Turcot syndrome
What are the variants of hamartomatous polyposis syndromes?
- Peutz-Jeghers Syndrome
- Juvenile Polyposis Syndrome
What is familial adenomatous polyposis?
- autosomal dominant mutation of APC gene
- in 20-30s
- has a lifetime risk of progression to cancer -> 100% by 45 years
how is familial adenomatous polyposis diagnosed & treated?
DIAGNOSIS
- flexible sigmoidoscopy/colonoscopy -> > 100 polyps
TREATMENT
- PROPHYLACTIC PROCTOCOLECTOMY + ilioanal anastomoses
- celecoxib & aspirin can induce regression
What is Gardner’s syndrome?
FAP + osteomas of mandible or skull + dental abnormalities
What is Turcot Syndrome?
FAP + brain tumors
What is Peutz-Jeghers syndrome?
hemartomatous polyps + melanotic macules
What is Juvenile polyposis syndrome?
hamartomatous polyposis syndromes in < 5 year old children
How are polyps treated?
Remove polyps to prevent cancer
- snare polypectomy <5mm
- endoscopic resection
- surgical resection -> lesions larger than 2cm
- > suspected malignancy
- > hereditary polyposis syndrome -> proctocolectomy
When is the peak incidence of colonic cancer?
7th decade
- 2nd cause of cancer death after lung
- all begin as benign polyps or adenoma (5%)
What does the transformation of a polyp into cancer depend on?
TYPE of polyp
- Adenomatous polyps -> VILLOUS
SIZE of polyp
- >5mm
NUMBER of polyps
- if multiple -> higher risk
AGE of patient
- older age -> higher risk
What is the most common type of colonic cancer?
ADENOCARCINOMA (95%)
What are the causes of colonic cancer?
- chronic inflammation
- bile salts
- increased fat
- decreased fibers
- decreased calcium
- body size & habitus
- decrease physical activity
- alcohol
What are the risk factors of colonic cancer?
- genetic/family history
- polyps
- inflammatory bowel disease
- diet, nutrition, smoking
What is the pathology of colonic cancer?
MACROSCOPIC
- polypoidal or sessile growth
MICROSCOPIC
- well differentiated
- moderately differentiated
- poorly differentiated
LN INVOLVEMENT
What are the clinical features of of colorectal cancer?
early -> asymptomatic
Constitutional
- weight loss
- night sweats
- fever
- fatigue
- abdominal discomfort
Right sided Colon Cancer
- occult bleeding or melena
- iron deficiency anemia (due to chronic bleeding)
Left sided colon carcinoma
- changes in bowel habits
- colicky abdominal pain (due to obstruction)
What investigations should be done to diagnose colon cancer?
- complete history & physical examination
- flexible sigmoidoscopy
- colonoscopy (gold standard)
- CEA
STAGING
- endorectal ultrasound -> rectal cancer
- chest x-ray -> metastasis
- liver ultrasound -> metastasis
- abdominal CT scan -> metastasis
When should screening for colonic cancer start?
COLONOSCOPY from 45-50 years
What are the indications of double-contrast barium enema?
- alternative to CT colongraphy in patients who cant undergo complete colonoscopy at presentation
findings
- endoluminal filling defect -> irregular margins
- apple core sign (napkin ring sign)
What is the 5 year survival rate of colonic cancer?
Stage I -> 90%
Stage II -> 80%
Stage III -> 27-69%
Stage IV -> 8%
What preop prep should be done on patient undergoing colonic cancer surgery?
- NPO
- IVF
- mechanical bowel prep
- chemical bowel prep
- cross match blood
- DVT prophylaxis
- Foley’s catheter
- stoma marking
when is right hemicolectomy indicated?
Tumor in the cecum & ascending colon
Resect -> part of distal ileum
- > ileocecal valve
- > cecum
- > ascending colon
- > hepatic flexure
- > proximal part of transverse colon
When is an extended right hemicolectomy indicated?
tumor near hepatic flexure/ proximal or middle transverse colon
Resection -> right hemicolectomy + transverse colon
When is left hemicolectomy indicated?
tumor in descending colon
Resect -> distal third of transverse colon
- > splenic flexure
- > descending colon
- > sigmoid colon
When is sigmoid colectomy indicated?
tumor in sigmoid colon
When is total or subtotal colectomy indicated?
- multifocal carcinomas
- underlying colonic disease -> FAP or UC
Which patients should get chemotherapy after their surgery?
- All stage 3 patients (positive nodes)
- High risk stage 2 patients (T3 or T4)
- > obstruction or perforation
- > poorly differentiated
- > mucinous
- > LV invasion
What is the systemic therapy used post op?
- Chemo -> FOLFOX (folinic acid + 5-FU + oxaliplatin)
- Biologics -> anti-VEGF antibodies (bevacizumab)
- > EGFR antibodies (cetuximab)
Should radiotherapy be used after surgery?
NO
has adverse effects on the small intestine -> enteritis & strictures
How should a colonic cancer patient be followed up with?
Office visit
- every 3 months for 2 years
- every 6 months for 3 years
Regular blood work
- CEA
Colonoscopy
- at year 1 -> if normal
- after 3 years -> if normal
- every 5 years
CT scan
- every year for 5 years
What is GIST?
submucosal lesion originating from the cells of Cajal
- c-KIT mutation
How should GIST be treated?
- wide surgical resection
- Imatinib (tyrosine kinase inhibitor) IF -> necrosis
- > >5cm
- > mitosis > 5 - high risk areas (duodenum or low rectal) need neoadjuvant therapy before surgery
What are carcinoid tumors?
APUD (neuroendocrine tumors) in submucosa
- produce 5-HT serotonin
- if they metastasis to liver -> skin flushing, GI diarrhea, heart, respiratory effects
- 24hr urinary 5-HIAA & blood chromogranin A
- surgery is the main treatment even if its to debulk
