Oncology - CRC

Question 1

Describe the pathophysiology of colorectal cancer

Answer 1

Normal epithelium > hyperproliferative epithelium > benign adenoma > severe dysplasia (pre-cancerous polyp) > adenocarcinoma > invasive cancer

Question 2

What type of carcinoma are most colorectal cancers? What are some rarer types?

Answer 2

95% adenocarcinoma (mucinous or signet ring)

Squamous cell 
Adeno-squamous carcinoma
Carcinoid
Gastrointestinal stromal tumour
Primary malignant lymphoma

Question 3

What dietary factors increase risk of colorectal cancer?

Answer 3

Risk factors for CRC

• Rich in animal fats + meat
• Poor in fibre - bowel exposed to carcinogens for longer
• Inflammatory bowel disease (ulcerative colitis)
• Familial association

Question 4

What genetic factors can increase risk of colorectal cancer?

Answer 4

Familial/genetic causes of CRC (5-10% tumours)

• HPNCC (a.k.a Lynch Syndrome)
• FAP (familial adenomatous polypoposis)
• Gardner’s syndrome

Question 5

How does left sided (sigmoid area) colorectal cancer present?

Answer 5

• Early change in bowel habit
• Rectal bleeding with mucus
• Tenesmus
• Obstruction (left colon is narrower and doesn’t expand as easily)

Question 6

How does right sided colorectal cancer present?

Answer 6

Weight loss
Iron deficiency anaemia
Abdominal pain
More advanced at presentation

Question 7

What are the red flags for colorectal cancer?

Answer 7

CRC red flags 
Abdominal pain
Anorexia 
Weight loss
Blood/mucous in stools
Change in bowel habit (including tenesmus)

Question 8

What is the screening programme for colorectal cancer?

Answer 8

1. All patients that turn 55 are invited for one off flexible sigmoidoscopy
2. All 60-74 year olds sent home test every 2 years (fecal occult blood, needs 3 samples)
3. Over 75s can ask for home test every 2 years

(patients at risk ulcerative colitis, a strong family history or a previous primary tumour should have regular colonoscopies)

If present, then onto 2w pathway.

Question 9

What investigations can be done for suspected colorectal cancer?

Answer 9

CRC investigations

1. Rectal Exam
2. Colonoscopy + biopsy
3. CT of thorax, abdo, pelvis) for staging (could do colongraphy to help look at polyms where colonoscopy not possible
4. Tumour marker CEA (carcino-embryonic antigen)-not diagnostic but good for monitoring

Question 10

What staging criteria is used for colorectal cancer?

Answer 10

Dukes Staging

A – Invasion into but not through the bowel wall (T1)
B – invasion through bowel wall (T2/3, N0, M0)
C – lymph node involvement
C1 – apical/high tide node is clear
C2 – apical node involvement
D – widespread metastases

Question 11

Whats the role of surgery in CRC?

Answer 11

Surgery in CRC

• Radical resection is the standard and can be curative
• Surgery in advanced disease is useful- resection of liver mets
• Palliative-surgery/stenting to prevent obstruction

Question 12

When is radiotherapy used in CRC?

Answer 12

• Radiotherapy is used in RECTAL cancers. Not colon cancer due to risk of toxicity to adjacent organs
• metastatic disease and local recurrences can be palliated with radiotherapy.

Question 13

Whats the treatment of colon cancer?

Answer 13

Colon cancer
- Local reoccurrence is uncommon so just do surgery. If tumour is locally advanced (T3/4- LN involvement then do neoadjuvant chemotherapy)

Question 14

Whats the treatment for rectal cancer?

Answer 14

Rectal cancer
-Local reoccurrence more common-so consider neoadjuvant treatment

1. Low risk- surgery alone
2. Moderate risk- neoadjuvant -radiotherapy before surgery to reduce reoccurrence
3. Hight risk- neoadjuvant chemoradiation to shrink before AND adjuvant chemotherapy (after surgery)

Question 15

Where are most of the large bowel tumours located?

Answer 15

CRC
About 1/3 in the rectum
About 1/3 on left side
About 1/3 remainder of colon

Question 16

What genes are associated with CRC?

Answer 16

• APC (5q21-22) (familial adenomatous polyposis coli) mutations are associated with the development of benign adenomas
• the progression to invasive carcinoma requires further mutations e.g. p53, DCC and RAS. Histology

Question 17

When would you give chemo in CRC?

Whats the most common chemo drug used in CRC?

Answer 17

• Adjuvant chemotherapy for CRC that is DUKES C
• 5-FU is the most commonly used drug
• Newer drugs such as Oxaliplatin and Irinotecan are now used

Question 18

What are some hollistic effects of CRC treatment?

Answer 18

Effects of treatment:

• Bowel: diarrhoea, frequency, urgency, incontinence
• Bladder: frequency, incontinence
• Sexual: impotence, vaginal stenosis
• Infertility: premature menopause
• Psychological: living with a stoma (body image), sexual, anxiety
• Financial: loss of job and earnings

Question 19

Staging for CRC?

Answer 19

The TNM staging system:
TX: Primary tumour cannot be assessed
T0: No evidence of primary tumour
T1: Tumour invades submucosa
T2: Tumour invades muscularis propria
T3: Tumour extends through muscularis propria into peri-colic tissues
T4: Tumour invades visceral peritoneum or invades / adheres to adjacent organ or structure

N0 No regional lymph node involvement.
N1 Involvement of 1-3 lymph nodes
N2 Involvement of 4 or more lymph nodes

MX: Distant metastasis cannot be assessed (not evaluated by any modality)
M0: No distant metastasis
M1: Distant metastasis
M1a: Confined to one organ or site (e.g. liver or lung) but not peritoneum
M1b: 2 or more sites (but not peritoneum)
M1c: Peritoneal spread

Question 20

What tumour marker is associated with colorectal cancer?

What other things cause raise in CEA

Answer 20

CEA
Normal <5,
-raised in smokers and itis conditions (IBD, hepatitis, pancreatitis or gastritis)

Question 21

What cancer are women who have HNPCC at risk of other than colorectal cancer?

Answer 21

Endometrial cancer