Oncology - CRC Flashcards
Describe the pathophysiology of colorectal cancer
Normal epithelium > hyperproliferative epithelium > benign adenoma > severe dysplasia (pre-cancerous polyp) > adenocarcinoma > invasive cancer
What type of carcinoma are most colorectal cancers? What are some rarer types?
95% adenocarcinoma (mucinous or signet ring)
Squamous cell Adeno-squamous carcinoma Carcinoid Gastrointestinal stromal tumour Primary malignant lymphoma
What dietary factors increase risk of colorectal cancer?
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
What genetic factors can increase risk of colorectal cancer?
Familial/genetic causes of CRC (5-10% tumours)
- HPNCC (a.k.a Lynch Syndrome)
- FAP (familial adenomatous polypoposis)
- Gardner’s syndrome
How does left sided (sigmoid area) colorectal cancer present?
- Early change in bowel habit
- Rectal bleeding with mucus
- Tenesmus
- Obstruction (left colon is narrower and doesn’t expand as easily)
How does right sided colorectal cancer present?
Weight loss
Iron deficiency anaemia
Abdominal pain
More advanced at presentation
What are the red flags for colorectal cancer?
CRC red flags Abdominal pain Anorexia Weight loss Blood/mucous in stools Change in bowel habit (including tenesmus)
What is the screening programme for colorectal cancer?
- All patients that turn 55 are invited for one off flexible sigmoidoscopy
- All 60-74 year olds sent home test every 2 years (fecal occult blood, needs 3 samples)
- 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.
What investigations can be done for suspected colorectal cancer?
CRC investigations
- Rectal Exam
- Colonoscopy + biopsy
- CT of thorax, abdo, pelvis) for staging (could do colongraphy to help look at polyms where colonoscopy not possible
- Tumour marker CEA (carcino-embryonic antigen)-not diagnostic but good for monitoring
What staging criteria is used for colorectal cancer?
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
Whats the role of surgery in CRC?
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
When is radiotherapy used in CRC?
- 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.
Whats the treatment of colon cancer?
Colon cancer
- Local reoccurrence is uncommon so just do surgery. If tumour is locally advanced (T3/4- LN involvement then do neoadjuvant chemotherapy)
Whats the treatment for rectal cancer?
Rectal cancer
-Local reoccurrence more common-so consider neoadjuvant treatment
- Low risk- surgery alone
- Moderate risk- neoadjuvant -radiotherapy before surgery to reduce reoccurrence
- Hight risk- neoadjuvant chemoradiation to shrink before AND adjuvant chemotherapy (after surgery)
Where are most of the large bowel tumours located?
CRC
About 1/3 in the rectum
About 1/3 on left side
About 1/3 remainder of colon
What genes are associated with CRC?
- 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
When would you give chemo in CRC?
Whats the most common chemo drug used in CRC?
- 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
What are some hollistic effects of CRC treatment?
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
Staging for CRC?
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
What tumour marker is associated with colorectal cancer?
What other things cause raise in CEA
CEA
Normal <5,
-raised in smokers and itis conditions (IBD, hepatitis, pancreatitis or gastritis)
What cancer are women who have HNPCC at risk of other than colorectal cancer?
Endometrial cancer
