Colorectal cancer Flashcards
What are the risk factors for colorectal cancer?
Colonic polyps
Family history
(Hereditary syndromes) Familial adenomatous polyposis, Hereditary nonpolyposis colorectal cancer (HNPCC)
Inflammatory bowel disease
(Diet and lifestyle)Smoking, Alcohol consumption, Obesity, Processed meat; high-fat, low-fiber diets
Age
What are the protective factors of colorectal cancer?
Physical activity
Diet rich in fiber and vegetables and lower in meat
Long-term use of aspirin and other NSAIDs
What are the clinical features of colorectal cancer?
Asymptomatic at early stage
In general right side bleed, left side cause obstruction
(Right side carcinoma) Iron deficiency anemia, Melena, Diarrhoea
(Left side carcinoma) Changes in bowel habits (size, consistency, frequency), Blood-streaked stools, Colicky abdominal pain due to obstruction
(Rectum) Hematochezia, ↓ Stool caliber, Rectal pain, Tenesmus, Flatulence with involuntary stool loss
What are the sites of common metastasis?
Liver
Lung
Lymphatics (mesenteric, para-aortic, and pelvic)
How is colorectal cancer staged?
TNM staging system
(Stage 1) Invasion of submucosa
(Stage 2) Invasion of muscularis propria but no lymph node involvement
(Stage 3) Invasion of subserosa or beyond + lymph node involvement, no other organs
(Stage4) Invasion of visceral peritoneum or adjacent organs
How is colorectal cancer diagnosed?
Digital rectal examination
Complete colonoscopy (gold standard)
(Staging) Endorectal US, CT, CXR
Tumour marker carcinoembryonic antigen (CEA)
What is the most common type of colorectal cancer and its pathophysiology?
Adenocarcinoma
Adenoma-carcinoma sequence is the progressive accumulation of mutations in oncogenes (e.g., KRAS) + tumor suppressor genes (e.g., APC, TP53) causing slow transformation of adenomas into carcinomas
What are the treatments for colorectal cancer?
(Surgical + Chemo adjuvant) Colectomy, lymph node dissection, removal of metastasis, chemo
Radiation therapy not standard
