Colorectal cancer Flashcards
Colorectal cancer is the ______ most common cancer in the UK.
4th - 2nd most common cause of cancer death
Strong risk factors?
1) Increasing age
2) Hereditary
- -> familial adenomatous polyposis
- -> hereditary nonpolyposis colorectal cancer (Lynch syndrome)
- -> Juvenile polyposis
- -> Peutz-Jegher’s syndrome
3) alcohol
4) smoking
5) processed meat
6) obesity
7) IBD
8) prev. exposure to radiation
Weak risk factors?
1) lack of fibre in diet
2) limited physical activity
3) Asbestos exposure
4) red meat (non-processed)
Classification to stage colorectal cancer?
DUKE’S!
A - limited to bowel wall (not beyond muscularis)
B - extends through bowel wall (beyond muscularis)
C - regional lymph nodes involved
D - distant mets
Another classification system?
TNM (tumour, node, mets)
Outline Ts in TNM? (Tis to T4)
Tis - carcinoma in situe/intramucosal cancer
T1 - extends through mucosa into submucosa
T2 - extends through submucosa to muscularis
T3 - extends through muscularis to subserosa
T4 - extends to neighbouring tissue/organs
Outline Ns in TNM (N0 to N2)
N0 - no regional lymph node involvement
N1 - mets to 1-3 regional lymph nodes
N2 - mets to 4+ regional lymph nodes
Outline Ms in TNM (M0 to M1)
M0 = no distant mets M1 = distant mets
Which patients benefit from adjuvant chemotherapy?
1) Duke’s Stage C
2) TNM Stage III (t1-4, n1-2, m0)
NHS screening programme?
- Faecal immunochemical test (FIT) every 2 years for men + women aged 60-74 years
- -> if +ve refer for colonoscopy
Aim of colorectal screening programme?
Detect cancer at early/asymptomatic stage, when it’s easier to treat patients & higher rate of survival
Urgent 2 weeks wait referral for possible colorectal cancer?
1) >40 w/ unexplained weight loss AND abdo pain
2) >50 w/ unexplained rectal bleeding
3) >60 w/ iron-deficiency anaemia OR changes in bowel habit
4) Proven faecal occult blood
Who might you perform a faecal occult blood test prior to referring?
1) >50 w/ unexplained abdo pain OR weight loss
2) >60 w/ anaemia
3) <60 w/ change to bowel habit OR iron deficient
Features?
- PR bleed
- abdo pain
- weight loss
- iron deficiency
- palpable mass
- tenesmus
- change in bowel habit/stool form (thin, small)
- abdo distension
- bowel obstruction
Initial diagnostic step?
Colonoscopy w/ biopsy
If risk of perforation then CT colonoscopy as alterantive
Investigation to stage?
CT chest, abdo, pelvis
Test to monitor response to interventions?
Carcinoembryonic antigen (CEA)
What imaging may be used if rectal disease suspected?
MRI or endorectal US > CT
Surgical management of rectal cancer?
- Anterior resection - if >8cm away from anal canal OR affects proximal 2/3 rectum
- Abdomino-perineal (AP) resection if <8cm from anal canal OR affects distal 1/3 rectum
Which rectal cancer patients receive chemo/chemoradio after surgery?
Stage III = post-op chemo
Stage IV = post-op chemoradio
Other non-surgical management options?
- chemo (if not suitable for surgery) –> FOLFOX
- monoclonal antibodies –> cetuximab
- stenting (as palliative if obstruction
What gene is mutated in Familial adenomatous polyposis (FAP)? Inheritance?
Adenomatous polyposis coli (APC) gene –> Autosomal dominant
Features of FAP?
1) develop hundreds of polyps in teens
2) develop colorectal cancer by their 20s
3) high risk of duodenal cancer
4) Gardener’s syndrome - also epidermal cysts, supernumerary teeth, osteomas, thyroid tumour
Managing patient with high risk of colorectal and duodenal cancer (FAP)?
- prophylactic proctocolectomy
- endoscopic surveillence
What genes are mutated in Hereditary non-polyposis colorectal cancer (HNPCC)/Lynch syndrome? Inheritance?
MLH1/MSH2 –> autosomal dominant
% risk of HNPCC/Lynch syndrome patient developing colorectal cancer?
80% by their 30s
Other cancers associated with HNPCC/Lynch syndrome?
- gastric
- endometrial (2nd most common after colorectal)
- breast
- prostate
How are HNPCC/Lynch syndrome patients managed?
Regular endoscopic surveillance
Mutation and inheritance of Peutz-Jeghers syndrome?
STK11 gene –> autosomal dominant
How do patients with Peutz-Jegher’s syndrome typically present? Managent?
Present in teens w/ mucocutanous pigmentation + haemartomatous polyps
Mange w/ regular endoscopic surveillence (risk is low)
Management of colon cancer if stage I-III?
Surgical resection +/- post-op chemotherapy
Stage III will benefit
Management of colon cancer if stage IV (mets)?
Pre-op chemo + surgical resection + post-op chemo
Type of surgery for tumours of the caecum, ascending colon & proximal transverse?
Right hemicolectomy
Type of surgery for tumours of the distal transverse & descending colon?
Left hemicolectomy
Type of surgery for tumour affecting the sigmoid colon?
Sigmoid colectomy
Colorectal cancer is most commonly associated with which IBD?
Ulcerative Colitis
Strong family history of colorectal and endometrial cancer is associated with which what?
HNPCC/Lynch Syndrome
What organism causing endocarditis is commonly assoc with colorectal cancer?
Streptococcus bovis
Investigation to test anastomoses are not leaking (after surgery)?
Gastrografin enema
What procedure would you perform if colorectal tumour and perforation occurs?
Hartmann’s procedure (which requires an end colostomy)
Which is most common cause of colorectal cancer (a) FAP or (b) HNPCC?
HNPCC (5%), FAP (<1%)
Most common histology of colorectal cancer?
Adenocarcinoma (90%)
Risk factor for anal cancer?
HPV
Why would you give a patient an epidural for abdo operations?
Accelerates the return of normal bowel function after surgery
