Colonic disorders and Cancer

Question 1

5 key features of colorectal cancer?

Answer 1

rectal bleeding- red blood,rectal cancer- dark red blood on surface of stool.
change in bowel habit- diarrohea more worrysome- tumour growth stimulates defecation, and tumour surface produces excessive mucus. May be cycles of diarrhoea and constipation if partial obstruction e.g. annular type at recto-sigmoid junction.
tenesmus- sensation in rectum of incomplete emptying after defecation, discomfort, tumour mistaken for faeces so want to continue emptying rectum. Also common in IBS.
weight loss
anaemia- Fe deficiency- reduced MCV-microcytic, hypochromic, reduced ferritin, reduced iron, increased total iron-binding capacity.

Question 2

why might alternating episodes of constipation and diarrhoea occur with a cancer at the recto-sigmoid junction?

Answer 2

initial obstruction produces constipation

colon above tumour then irritated by impacted faeces, so these liquefy before passing through stenosis as loose stool.

Question 3

presentation of rectal cancer following liver metastasis?

Answer 3

upper abdom. pain
and/or malaise
palpably enlarged liver

Question 4

problems associated with perforation of a colonic carinoma?

Answer 4

pericolic abscess
peritonitis
fistulae

Question 5

benefit of flexible sigmoidoscopy over a CT colonogram in investigating colon cancer?

Answer 5

can carry out biopsy to produce +ve evidence of cancer
no radiation
don’t experience clasutrophobia
however, CT may be preferred in elderly who can’t tolerate sigmoidoscopy* bowel preparation required to empty bowels- ptnts can die on the toilet if left alone. Can also CT to look for any liver involvement.

Question 6

deformity visible on barium enema in colon cancer?

Answer 6

apple core stricture

Question 7

differential diagnoses for colon cancer?

Answer 7

diverticular disease
IBD
IBS
ischaemic colitis
haemorrhoids
anal Ca
pneumatosis coli

Question 8

contrast presentation of L and R sided colorectal carcinomas?

Answer 8

L= PR bleeding/mucus, altered bowel habit, tenesmus, mass PR.
R= weight loss, anaemia, abdom pain, lump- as can grow very large before noticeable symptoms prompting presentation.

Question 9

what test may be used to monitor colorectal carcinoma and effectiveness of tment?

Answer 9

carcinoembryonic antigen

Question 10

when would an anterior resection be used in colorectal carcinoma?

Answer 10

for low sigmoid or high rectal tumours

anastamosis then achieved, must have good b.supply

Question 11

management consideration for obstruction in palliative approach to colorectal cancer?

Answer 11

endoscopic stenting

Question 12

describe use of adjuvant chemotherapy in colon cancer

Answer 12

adjuvant 5-FU with or without agents such as folinic acid reduce Dukes’ C mortality-colorectal Ca involving regional lymph nodes, improving disease free survival and overall survival

chemotherapy also used in palliation of metastatic disease

Question 13

how does the NHS bowel cancer screening programme work?

Answer 13

screening offered every 2 yrs to all men and women between 60 and 69 yrs of age used faecal occult blood testing- small amounts of blood not normally seen/aware of in stools are detected. Abnormal results usually followed up with colonoscopy= more accurate than sigmoidoscopy but more likely to produce perforation.

Question 14

how is metastatic spread of colorectal cancer investigated?

Answer 14

CT chest, abdomen and pelvis

Question 15

what is an MRI of the pelvis useful for in colorectal cancer?

Answer 15

preoperative staging of rectal tumour and for planning preoperative radio- and chemotherapy

Question 16

how are tumours of the lower 1/3 of rectum treated surgically? (within 5 cm of anal verge)

Answer 16

abdomino-perineal excision of rectum and anus, with permanent left iliac fossa end colostomy
insufficent rectum or anus for good anastamosis
adjunctive radiotherapy may reduce local recurrene incidence post resection

Question 17

usefulness of pre-op radiotherapy in rectal cancer (neoadjuvant)?

Answer 17

importance in reducing local recurrence and increasing 5yr survival, in combination with total mesorectal excision
with or without chemo may downstage initially unresectable rectal tumours, but chemo pre or post op in rectal Ca despite reducing local recurrence has not been shown to improve survival.

Question 18

indications for total mesorectal excision (TMR)?

Answer 18

his refers to excision of the rectum as widely as possible, including the mesorectum, to reduce the likelihood of local recurrence of rectal Ca
this is done as part of an anterior resection for rectal adenocarcinoma, where the 2 ends of the bowel are anastomosed.
mesorectum= fold of peritoneum connecting upper rectum with sacrum.

Question 19

investigation of CR cancer that can be used to get through a stricture?

Answer 19

barium enema- as gas and air

carry out if obstructive symtpoms

Question 20

why must MRI all rectal cancers?

Answer 20

can invade easily

Question 21

problems with obstruction that necessitates emergency hartmann’s procedure for bowel cancer?

Answer 21

sepsis
hypoalbuminaemia
CVS instability

so anastamosis wouldn’t have adequate b.supply, so would be prone to anastamotic leak.

Question 22

why is bowel prep given if pre-op chemo in tment of bowel cancer?

Answer 22

don’t want faecal matter to go through anastamosis

Question 23

typical presentation of acute appendicitis?

Answer 23

gradual onset colicky, central abdominal pain
with anorexia and vomiting
pain within hrs localises to RIF as parietal peritoneal irritation with transmural inflammation
systemic response= tachycardia, fever, dehydration
tender RIF mass= inflammatory mass or abscess around appendix.

Question 24

DDs for acute appendicitis?

Answer 24

mesenteric adenitis
lower UTI
pyelonephritis
salpingitis
ectopic pregnancy
ruptured ovarian follicle
ruptured ovarian cyst
acute cholecystitis
terminal ilieitis
inflammatory or perforated caecal carcinoma.

Question 25

young ptnt presenting with RIF pain. other than an inflamed appendix, what else might you be looking for in laparoscopy?

Answer 25

a Meckel’s diverticulum= can become inflamed and present similarly. results from incomplete closure of vitelline duct which connected developing gut with yolk sac during development. symptoms usually due to presence of bands or ectopic gastric mucosa within diverticulum, ectopic gastric mucosa causes haemorrhage and perforation.

mesenteric adenitis?

Question 26

complications of a Meckel’s diverticulum?

Answer 26

obstruction- e.g. due to small bowel volvulus around a band from diverticulum to umbilicus- T10.
inflammation
peptic ulceration with pain
bleeding
perforation

Question 27

tment of symptomatic meckel’s diverticulum?

Answer 27

resection- diverticulectomy or segmental ileal resection.

Question 28

investigations to aid acute appendicitis diagnosis?

Answer 28

WCC
urine analysis- exclude UTI, and pregnancy test- hCG, exclude EP
barium enema- apendiceal lumen will not fill, but enema may not reach appendix- false +ve
USS
CT
laparoscopy- but GA and specific complics
catheter peritoneal aspiration
active observation
computer-aided diagnosis

Question 29

bowel prep that can be given on day of endoscopy?

Answer 29

phosphate enema e.g. for flexible sigmoidoscopy? **

Question 30

indications for adomino-perineal excision/resection of rectum?

Answer 30

rectal cancer too low down-within 5cm of anal verge/dentate line
internal sphincter involvement

so require removal of rectum and anus with, with end of large bowel used to form a permanent end colostomy.

Question 31

what increases risk of anal cancer?

Answer 31

syphilis
anal warts
anoreceptive homosexuals

Question 32

where do anal cancers spread?

Answer 32

if above pectinate line, to pelvic LNs

if below, to inguinal LNs

Question 33

presentation of ptnt with anal cancer (usually squamous cell in 80% of cases)

Answer 33

bleeding
pain
change in bowel habit
pruritis ani
masses
stricture

Question 34

differential diagnoses for anal cancer?

Answer 34

perianal warts

crohn’s disease

Question 35

tment of anal cancer?

Answer 35

radiotherapy +5-FU and mitomycin/cisplatin

Question 36

% of colorectal Cas that have liver metastases at presentation?

Answer 36

20%

Question 37

sites of metastasis of colorectal Ca?

Answer 37

liver-most common
peritoneum
lungs
brain
bone

Question 38

RFs for colorectal Ca?

Answer 38

increasing age
colorectal polyps-may be history of FAP
FH of colon cancer or colonic polyps
chronic IBD
acromegaly-patients from age of 40 recommended to have regular colonoscopy screening
abdominal radiotherapy
obesity
high red meat and saturated fat consumption
high sugar consumption
smoking

Question 39

describe the UK bowel Ca screening programme

Answer 39

FOB-faecal occult blood testing, offered to men and women aged between 60 and 74 every 2 years in England, and those between 50 and 74 in Scotland.
Used to detect traces of blood in stools which isn’t visible to the patient. Involves wipe stool sample on a special card, which is sent for testing in a hygienically sealed, prepaid envelope. Results of your test in the post within 2 weeks.

Question 40

recommendations for bowel Ca screening in patients with acromegaly?

Answer 40

Because patients with acromegaly have an increased prevalence of colorectal adenomas and cancer, it is recommended that patients with acromegaly should be offered regular colonoscopy screening, starting at the age of 40 years. The frequency of repeat colonoscopy should depend on the findings at the original screening and the activity of the underlying acromegaly:
Patients with an adenoma at first screening or elevated serum IGF-1 level above the maximum of the age-corrected normal range should be offered 3 yearly screening.
Patients with a negative first colonoscopy or a hyperplastic polyp or normal GH/IGF-1 levels should be offered screening every 5-10 years.

Question 41

causes of ischaemic colitis?

Answer 41

most common= mesenteric vessel atherosclerosis
IMA thrombosis
mesenteric arterial emboli
cholesterol emboli
decreased CO or arrhythmias
trauma
can be result of venous occlusion
bowel obstruction-colon proximal to obstruction is dilated which impairs blood flow to distended region, also occurs with pseudo-obstruction (Ogilvie's syndrome)*
cocaine abuse, methamfetamine
oestrogen drugs e.g. OCP
colectomy with IMA ligation
SLE
sickle cell disease

Question 42

ischaemic colitis presentation?

Answer 42

acute onset abdo pain, commonly LIF
N+V
diarrhoea with dark blood in later stages
marked LIF tenderness

Question 43

pathophysiology of ischaemic colitis?

Answer 43

result of blood circulation compromise to colon
Marginal branches of the middle colic from SMA and left colic from IMA supply the transverse and descending segments of the colon and, with an arterial and lymphatic watershed existing near to the splenic flexure, supported by an additional vascular arcade, this part of the colon is at risk.

Question 44

how is ischaemic colitis investigated?

Answer 44

ABG-metabolic acidosis-decrease HCO3- and pH less than 7.35
colonoscopy-swollen blue mucosa, rectal sparing
plain AXR-abnormal segment outlined with gas
barium enema-‘thumb printing’ in early stage due to SM swelling

Question 45

medical management of ischaemic colitis?

Answer 45

bowel rest
supportive care-fluid replacement
Abx
ischaemia usually resolves once cause of hypoperfusion alleviated, as ischaemia mucosal rather than full thickness

most recover but strictures common
could do percutaneous transluminal angioplasty and EV stent insertion
gangrenous colitis would require prompt resuscitation followed by affected bowel resection and stoma formation

Question 46

what is the clinical importance of pseudo-obstruction of the colon?

Answer 46

mimics large bowel obstruction caused by colorectal Ca
water soluble barium enema will distinguish it from large bowel obstruction as barium able to pass through all of distended bowel whereas will be halted by the obstruction in large bowel obstruction e.g. with Ca
pseudo-obstruction should avoid surgery, decompression colonosocopy may help, and can give neostigmine in acute situation if no cardiac contraindications.

Question 47

most common sites of colorectal Ca?

Answer 47

rectosigmoid

caecum

Question 48

genetics of colorectal Ca?

Answer 48

accumulation of abnormalities in growth-regulating genes allows stepwise progression from normal mucosa to adenoma to invasive cancer.
mutations include APC-adenomatous polyposis coli, a TSG-causing loss of this protein, K-ras mutation, TP53-tumour suppressor p53, and altered DNA methylation.
lifetime risk is 1 in 10 if one 1st degree relative affected under the age of 45yrs, and 1 in 17 if 1st degree relative affected at any age.
15% of sporadic colorectal cancers-acquired genetic changes that happen by chance, show microsatellite instability and 50% show loss of heterozygosity.

Question 49

indications for 2ww referral in colorectal Ca?

Answer 49

rectal bleeding and persistent change in bowel habit for more than 6 weeks
recent onset of looser stools and/or frequency of defecation, persisting for more than 6 weeks
persistent rectal bleeding without anal symptoms in those over 45yrs, with no obvious external evidence of benign anal disease
Fe deficiency anaemia without an obvious cause and Hb less than 10g/dL
palpable abdo or rectal mass

Question 50

what can be measured that increasing levels of suggests colorectal Ca recurrence?

Answer 50

serum CEA-carcinoembryonic antigen

Question 51

when is post op radiotherapy required in colorectal Ca?

Answer 51

if following resection, histology shows that the margins are involved with Ca
only if it wasn’t used prior to surgery

Question 52

indications for anterior resection of CR cancer?

Answer 52

low sigmoid or high rectal cancers-more than 5cm away from the anal verge
anterior resection allows 1st op anastomosis to be formed between the 2 bowel ends, but often is initially protected with a temporary loop ileostomy which is closed in a relatively minor op several mnths later after complete anastomosis healing been demonstrated by contrast enema.
loop ileostomy preferred to loop colostomy as better blood supply to bowel facilitating subsequent closure
must resect as far down principal artery as possible as lymphatic drainage runs alongside arterial inflow

Question 53

what is a double barrelled colostomy and when is it used?

Answer 53

also known as a Paul-Mikulicz colostomy, this comprises proximal and distal ends of colon brought out adjacent to each other, and is useful in sigmoid volvulus tment in which there is usually sufficient distal colon.

Question 54

why is radiotherapy NOT useful for colonic cancers?

Answer 54

difficulties delivering sufficient dose to tumour without excess toxicity to adjacent structures e.g. small bowel

Question 55

how are mets assessed for post-surgery for colorectal Ca?

Answer 55

yrly CT scanning chest and abdo to detect operable liver metastases, performed for up to 3 yrs post-surgery

Question 56

what is the function of forming a loop ileostomy when an anterior resection is performed for a lower sigmoid or upper rectal cancer?

Answer 56

the loop ileostomy is a temporary defunctioning loop ileostomy, to allow faecal matter to be collected in a stoma bag rather than passing through the newly formed anastamosis to allow the anastomosis sufficient time to heal to reduce the risk of anastamotic leak.