Colorectal carcinoma Flashcards
Define colorectal carcinoma
Malignant adenocarcinoma of the large bowel
Distribution of colorectal carcinomas
4
Rectum & sigmoid - 60%
Descending colon - 5%
Ascending colon - 20%
Rest -15%
Aetiology of colorectal carcinoma
2
Environmental & genetic
Sequence of genetic changes that go from normal bowel epithelium to cancer (e.g. APC, K-Ras)
Risk factors for colorectal carcinoma
5
Western diet (e.g. red meat, alcohol) Colorectal polyps Previous colorectal cancer FH IBD
Epidemiology of colorectal carcinoma
death, age
2nd MOST COMMON cause of cancer death in the West
Average age of diagnosis 60-65 yrs
Presenting symptoms of colorectal carcinoma
general + 3 + 5 + 2
Depend on size & location of tumour
Left sided colon & rectum
Change in bowel habit
Rectal bleeding (blood or mucus mixed w/ stool)
Tenesmus (due to space-occupying tumour in the rectum)
Right sided colon Presents later Anaemia symptoms (lethargy) Weight loss Non specific malaise Lower abdominal pain (rare)
20% tumours present as an EMERGENCY with pain & distention due to:
Large bowel obstruction
Haemorrhage or peritonitis due to perforation
Signs of colorectal carcinoma on physical examination
5
Anaemia Abdominal mass If metastatic: hepatomegaly ascites Low lying rectal tumours may be palpable on DRE
Investigations for colorectal carcinoma
5
Bloods Stools Endoscopy Double contrast barium enema Contrast CT
Investigations for colorectal carcinoma - bloods
3
FBC - anaemia
LFTs
Tumour markers (CEA)
Investigations for colorectal carcinoma - stools
FOBT - screening test
Investigations for colorectal carcinoma - endoscopy
3
Sigmoidoscopy
Colonoscopy
Can be used to biopsy tumour
Investigations for colorectal carcinoma - double contrast barium enema
May show “apple core” strictures
Investigations for colorectal carcinoma - contrast CT
For staging (Duke’s)
