Cancers

Question 1

what is the most common place for colorectal cancer to occur?

Answer 1

in the rectum- 50%, all of which are palpable on DRE

Question 2

name 5 risk factors for colorectal cancer

Answer 2

1. familial adenomatous polyposis
2. high fat diet
3. alcoholic
4. ulcerative collitis
5. hereditary non polyposis colorectal cancer

Question 3

briefly describe the pathogenesis of colorectal cancer formation

Answer 3

1. mutation in tumour suppressor gene (APC)
2. epithelial cells proliferate= benign polyp
3. activation of oncogene; K-RAS- further proliferation of epithelial cells and angiogenesis is promoted forming an adenocardinoma
4. defected DNA repair pathway (HMLHT) no inhibition of growth- adenoma proliferates becoming a malignant carcinoma

Question 4

give 3 features a rectal carcinoma may present with

Answer 4

1. PR bleed
2. tenesmus- feeling of needing to poo but not satisfied when they do
3. mucus and thin stools

Question 5

give 3 features of a carcinoma in the left colon and sigmoid colon

Answer 5

PR bleed
thin stools
change in bowel habit; alternating between diarrhoea and constipation
altered stool pattern

Question 6

give 3 features of a carcinoma in the right colon

Answer 6

NO PR bleed
anaemia
palpable mass- has to be massive as the right colon has a wide diameter

Question 7

briefly describe the staging of colorectal cancer (Dukes stagins)

Answer 7

A= tumour has invaded the submucosa
B= tumour has invaded the muscularis propria
C= tumour has invaded into at least one local lymph node
D= tumour has metastasised; most commonly to the liver and the lung

Question 8

name 2 common sites where colorectal cancer might metastasise to?

Answer 8

Liver

lungs

Question 9

which gene is responsible for the 1000’s of polyps developing in the 2nd and 3rd decade in familial adenomatous polyposis?

Answer 9

APC gene mutation on chromosome 5

Question 10

how does the gene mutation in familial adenomatous polyposis allow for the accumulation of polyps in the colon?

Answer 10

it enables the over-expression of beta catenin, which increases DNA transcription, which increases epithelial proliferation which then progresses to forming an adenoma

Question 11

which inherited condition associated with colorectal cancer does not respond well to chemotherapy?

Answer 11

hereditary non polyposis colorectal cancer- because mutations in both DNA repair genes means that there is no way of recognising abnormal cells which are produced in chemotherapy.

Question 12

what investigations would you do if you suspected a patient to have colorectal cancer?

Answer 12

1. Faecal occult blood smaple- 3 samples of faeces taken for analysis
2. FBC: may show elevates CEA- carcinoembryonic antigen (tumout marker)
3. barium enema (liquid barium sulphate) makes good visualisation of the bowel
4. colonoscopy- gold standard + biopsy for histological staging
5. CT scan for those less suited to colonoscopy; elderly- painful, needs sedation, increased risk of infection

Question 13

what are the treatment options for metastatic colorectal cancer

Answer 13

the prognosis is poor- treatment will not be curative. Radiotherapy is most commonly used for palliation. Chemotherapy and surgery can also be useful.