Colorectal Cancer Flashcards
State a typical presentation for colorectal cancer?
Left side: PR bleeding, change in bowel habit, tenesmus, mass on DRE (rectal), May present with ob
R side: anaemia + FLAWS
What is tenesmus?
Tenesmus is a medical term used to describe the sensation of being unable to empty your bowel after you have already defecated. Tenesmus is commonly associated with inflammatory bowel disease (IBD) but may also be caused by hemorrhoids, infections, and even cancer.
define colorectal cancer?
malignant adenocarcinoma of the large bowel
describe the distribution of colorectal cancer?
60% - rectumand sigmoid
30% - ascending colon
10% - rest of colon
what is the staging used for colorectal cancer and describe it?
A: limited to muscularis mucosae, 93% 5yr survival rate
B: extension through muscularis mucosae, 77%
C: involvement of regional lymph nodes, 48%
D: distant metastases, 6.6%
outline the aetiology of colorecal cancer?
Environmental and genetic
There is a sequence of genetic changes that go from normal bowel epithelium to cancer (e.g. APC then COX2 over-expression then K-Ras then p53). There is a sequence from epithelial dysplasia to adenoma to carcinoma, involving accumulation of genetic changes in oncogenes and tumour suppressor genes.
Some inherited conditions are associated with high rates of colorectal carcinoma e.g. FAP, HNPCC
what are the risk factors for colorectal cancer?
Western diet (e.g. red meat, alcohol, low fibre)
Obesity
Colorectal polyps
Previouscolorectal cancer
Family history
IBD (UC > crohns)
Alcohol
Smoking
Chronic bowel inflammation e.g. IBD
summarise the epidemiology of colorectal cancer?
SECOND MOST COMMON cause of cancer death in the West
3rdmost common cancer and 2ndmost common cause of UK cancer deaths
UK: 20,000 deaths per year
Average age of diagnosis: 60-65 yrs
what do the presenting symptoms of colorectal cancer depend on?
size and the location of the tumour
what are the presenting symptoms of colorectal cancer if the tumour is on the left sided colon and rectum?
Change in bowel habit
Rectal bleeding (blood or mucus mixed with the stools) - no blood present if in ascending or transverse colon therefore for these you would need a full colonoscopy if change in bowel habits are found after 60yrs
Tenesmus(due to a space-occupying tumour in the rectum)
Tenesmus = sensation of incomplete emptying after defecation
More likely to obstructbecause diameter is smaller on the left side and the bowel content more solid.
MassPR in 40-80% in rectal carcinomas
what are the presenting symptoms of colorectal cancer if the tumour is on the right side of the colon?
Presents later
Anaemia symptoms (lethargy)
Weight loss
Non-specific malaise
Lower abdominal pain (rare)
Abdominal distention in advanced disease due to ascites or intestinal obstruction
what is an important thing to note in the symptoms of colorectal cancer?
20% of tumours will present as an EMERGENCY with pain and distension due to:
Large bowel obstruction
Haemorrhage or peritonitis due to perforation
what are the signs of colorectal cacner on physical examination?
Anaemia, especially in R-sided
Abdominal mass
If metastatic:
- Hepatomegaly (lungs and liver and lymph N are likely areas of mets)
- Ascites (shifting dullness)
Low-lying rectal tumours may be palpable on DRE
what are the appropriate investigations for colorectal cancer?
bloods
- FBC - anaemia
- LFTs and renal function (for baseline assessments) – usually norm even when liver metastases is present
Colonoscopy- GOLD STANDARD- biopsy tumour to confirm diagnosis
double- contrast barium enema
CT colonoscopy
contrast CT of thorax, abdo, pelvis
what do we look for in the bloods for colorectal cancer?
FBC - anaemia
LFTs and renal function (for baseline assessments) – usually norm even when liver metastases is present
Tumour markers (CEA) - only measured on confirmation of diagnosis (main use is to detect relapse of cancer after surgical treatment and evaluation of chemo)
