Colorectal Cancer Flashcards
What is colorectal cancer
Cancer of colon and rectum 3rd most common non skin cancer in both sexes Affects M&W equally Easily cured w/ early detection Peak ages are 50-70
Risk factors for colorectal cancer
Fam history
Colorectal adenomas
Chronic inflammatory bowel diseases
Low diner diet
Chronic alcoholism & smoking
Obesity
Precious malignancy
- ovarian
- endometrial
- breast
Common sites of colorectal cancer
60% rectum
20% sigmoid colon
10% ascending Cecum and other sites
Familial syndromes linked to colorectal cancer
Most cases are sporadic!!!!!
HNPCC
- d/2 germline mutations of dna mismatch repair genes
- 5% risk
Lynch syndrome 1&2
Familial adenomatous polyposis
- autosomal dominant
- mutation of tumor suppressor gene
- 95% risk
Hamartomatous polyposis (Peru’s-jeghers syndrome
Carcinogenesis of colorectal cancer
Normal epithelium undergoes hyperplasia
Adenomatous polyps forms
- activation of K-ras (oncogene that increases nuclear cell signalling)
- inactivation Of tumor suppressor genes e.g. APC In familial adenomatous polyposis
- microsatelite instability showing defect in DNA MMR
Adenocarcinoma
Metastatic Cancer
-defect in p53
Histology iof colorectal Cancer
90% adenocarcinoma
2/7% carcinoid
Prognostic and predictive factors of colorectal cancer
CEA
- prognostic factor before operation
- post operatively shows therapeutic effect of operation
KRAS
Predicts resistance to anti-EGFR therapy
Mutated kras is u responsive to this therapy
TNM Staging of colorectal cancer
Tis: only in epithelium/ lamina propris T1: In submucosa T2: into mucscularis pro pros T3: into subserosa T4a: into visceral epithelium T4b: into/ attaches to adjacent organs
N1a: 1 region LN N1b: 2-3 regional LN N1c: tumor nodules no colon that don’t look like LN’s N2a: 4-6 LN N2b: 7+
M1a: spread to 1 place beyond colon & rectum
M1b: more than 1 place beyond rectum and colon
M1c: spread to peritoneal surface
Ajcc staging of colorectal cancer
Stage 0: Tis, N0, M0
Stage 1: T1-2, N0, M0
Stage 2a: T3, N0, M0
Stage 2b: T4a, N0, M0
Stage 2c: T4b, N0, M0
Stage 3a: T1-2, N1-2, M0
Stage 3b: T3-4, N1-2, M0
Stage 3c: Any T, N2, M0
Stage 4: any T, any N, M1
Sx of colorectal cancer
Fatigue Weight loss Irregular bowel movements (paradoxical diarrhoea Pencil like stools Visible or occult blood in stools Pain
Dg of colorectal cancer
Colonoscopy w/ biopsy
Imaging
- US for hepatic metastasis
- CT/MRI
- water soluble contest enema d/2 perforation risk
Surgical rx of colon cancer
90% rx w/ surgery
Curative intent involves
1) tumor resection
2) LN resection (paraaortic And Inguinal)
3) mesentery resection
4) resection of metastasis if only limited to one organ system
(Liver then lung)
Palliative I rent - resection If tumor to prevent complications e.g Ileus Hemmorhage Perforation Fistula
Colon cancer chemotherapy and Post operative care
Depends on outcome of surgery and stage
Stage 1: close monitoring after curative surgery
Stage 3: post op chemotherapy
- FOLFOX for 6 months
Stage 4: palliative chemotherapy
- bevacizumab
- prolongs survival
- Used in unknown or wilt type KRAS
- cetuximab used in mutated kras
Rx of rectal cancer
1) sphincter preserving approach used for tumors in upper and mid 3rd of rectum
2) abdominoperineal excision w/ permanent t colostomy for tumors in lower 3rd
3) resection of SOLITARYA metastasis in liver/ lungs
Rectal cancer chemo and Post operative care
Stage 1: close monitoring offer curative operation
Stage 2&3: adjuvant radiochemotherapy
- radiotherapy w/ continue 5-FU infusion
Stage 4: limited hepatic metastasis shows ambiguous effect of adjuvant post op chemo
Stage T4, N1, M0: PRE operative radiochemotherapy to make the pt operable
Palliative chemo is same as colon cancer
