Colorectal cancer Flashcards
What is colorectal cancer?
Cancer of the colon and rectum.
3rd most common malignancy.
Usually adenocarcinoma on histology.
What are the signs and symptoms of colorectal cancer?
Abdominal pain Unintentional weight loss Altered bowel habit Faecal occult blood Anaemia Fatigue
What are the causes of colorectal cancer?
Multifactorial and often unknown.
There are risk factors that may predispose.
What investigations are performed to confirm colorectal cancer?
Bowel cancer screening programme: faecal occult blood test in men and women aged 60-69 years.
Bloods: FBC for iron deficiency anaemia and carcinoembryonic antigen (CEA) tumour marker.
Endoscopy: colonoscopy/sigmoidoscopy.
Imaging: double contrast barium enema study ‘apple core’ sign; virtual colonoscopy.
What is the treatment of colorectal cancer?
Depends on the extent of disease. Assessed using Duke’s staging system or TNM system.
Conservative: patient education and referral to Macmillan nurses.
Medical: chemotherapy (oxaliplatin, folinic acid and 5-flurouracil is the most common regime); radiotherapy may also be used.
Surgery: surgical resection is usually treatment of choice.
What is the complication of colorectal cancer?
Obstruction and metastasis.
What are the risk factors for colorectal cancer?
Smoking.
Increased age.
Family history.
IBD.
Streptococcus bovis bacteraemia.
Congenital polyposis syndromes: juvenile polyposis syndrome (autosomal dominant but may occur spontaneously, not malignant); Peutz-Jegher’s syndrome (autosomal dominant, increased risk of CRC, melanosis is present on oral mucosa).
Genetic predisposition: familial adenomatous polyposis (FAP; autosomal dominant, mutation of APC gene on chromosome 5, 100% lead to CRC); hereditary nonpolyposis colorectal cancer (HNPCC; autosomal dominant, mutation of DNA mismatch repair gene).
Explain the Duke’s staging system.
Stage A: confined to muscularis mucosa, 90% 5 year survival.
Stage B: extends through muscularis mucosa, 65% 5 year survival.
Stage C: lymph node involvement, 30% 5 year survival.
Stage D: distant metastases, <10% 5 year survival.
Explain the TNM system.
T: carcinoma in situ T1: submucosa invaded T2: muscularis mucosa invaded T3: tumour has invaded subserosa but other organs have not been penetrated T4: adjacent organs invaded
N1: metastatic spread to 1-3 regional lymph nodes
N2: metastatic spread to >4 regional lymph nodes
M0: no distant metastases present
M1: distant metastases present