Colorectal Cancer Flashcards
Risk factors
Age Male Previous adenoma/CRC Diet Alcohol Obesity Lack of exercise Smoking Diabetes Mellitus IBD
Majority of colorectal cancers arise from
Pre existing polyps
Polyps
Protuberant growths
Variety of histological types
Epithelial or mesenchymal
Benign or malignant
Colorectal polyps in the form of
Adenomas - benign/premalignant
Either tubular or villous
Activation of oncogene (adenoma)
k-ras, c-myc
Loss of tumour suppressor gene (adenoma)
APC, p53, DCC
Defective DNA repair pathway genes (adenoma)
Microsatellite instability
Presentation of colorectal cancer
Rectal bleeding
Altered bowel opening to loose stools
Iron deficiency anaemia (more likely to have right sided colonic malignancy)
Palpable rectal or right lower abdominal mass
Acute colonic obstruction if stenosing tumour
Systemic symptoms of malignancy => weight loss, anorexia
Investigation
Colonoscopy
Radiological imaging
Why use colonoscopy for investigation?
Allows biopsies to be taken
Therapeutic as also allows for polypectomy
Radiological imaging techniques
Barium enema
CT colonography
Treatment
Surgery is basis of therapy Endoscopic or local resection for polyps Partial hepatectomy for metastases Chemotherapy Radiotherapy
Chemotherapy
Adjuvant
Positive lymph node histology
Mops up micrometastases
Radiotherapy
Rectal cancer only
‘neoadjuvant’ +/- chemotherapy to control primary tumour prior to surgery
Neoadjuvant
Given before main therapy
