Pathology of Colorectal Cancer Flashcards
1
Q
Give an overview of the epidemiology of colorectal cancer.
A
- 3rd most common cancer diagnosed worldwide.
- Incidence and mortality are 25% lower in women than men.
- Highest rates in developed countries - can be considered a ‘Western disease’.
- Decreased in developed countries due to nationwide screening programmes, improved surgery and uptake of colonoscopies.
- However, an increased trend in <50s has been observed - potentially due to lifestyle, obesity and environmental factors.
2
Q
What are the risk factors for colorectal cancer?
A
-
Non-modifiable
- Age
- Sex
- IBD
- FHx
-
Modifiable
- Diet (low fibre and high fat)
- Lack of exercise
- Smoking
- Alcohol
- Obestiy
3
Q
Describe the clinical presentation of coloretal cancer.
A
- Early stage CRC is usually asymptomatic until more advanced stages.
- Therefore screening plays a major role in diagnsing curable (early stage) disease or precursors to disease.
- Symptoms:
- Occult or overt rectal bleeding
- Change in bowel habit (diarrhoea or constipation)
- Pain & discomfort in bowel
- Weakness and fatigue
- Weight loss
4
Q
How is colorectal cancer diagnosed?
A
- Rectal bleeding and discomfort in bowel and change in bowel habit may not be due to cancer. Bleeding is a common symptom of both benign and malignant causes.
-
Endoscopy
- Colonoscopy is the most common, but invasive, method to diagnose colorectal cancer.
-
Imaging
- CT colonography is used as a complementary imaging method for the diagnosis of polyps and colorectal cancer.
- Also used for assessing the stage of the disease both locally (colon) and distant (e.g. lesions in the liver).
-
Labooratory
- Complete blood count, as checking CEA concentrations at the time of diagnosis (high CEA = worse prognosis).
-
Pathology
- Histological assessment is the basis for pathological diagnosis and staging of the disease.
- Mismatch repair testing (immunohistochemistry) is used for diagnosis of lynch syndrome and adjuvant immunotherapy decision making.
5
Q
Name and describe each layer of the colon.
A
6
Q
Which features of the colon are depicted in these histological sections?
A
7
Q
Name each of these features of colon cancer histopathology shown in this slide.
A
8
Q
Name each of these features of colon cancer histopathology shown in this slide.
A
9
Q
What are the factors which affect prognosis for colorectal cancer?
A
- The earlier the detection, the better the prognosis.
- Generally:
- 1 year survival 80%
- 5 year survival 60%
- What affects prognosis and survival?
- TNM staging
- Other histopathological features
- Health and fitness
- Effectiveness of surgery and treatment
10
Q
Describe the ‘T’ staging of colorectal cancer.
A
- T = extent of local invasion.
- pT0 = no evidence of primary tumour.
- pT1 = tumour invades submucosa.
- pT2 = tumour invades muscularis propria.
- pT3 = tumour invades into subserosa or into perirectal tissues.
- pT4 = tumour perforates visceral peritoneum (4a) and/or directly invades other organs or structures (4b).
11
Q
Describe the ‘N’ staging of colorectal cancer.
A
- pN = extent of regional lymph node invasion.
- pN0 = no positive regional lymph nodes.
- pN1 = 1-3 regional lymph nodes involved.
- pN1a = metastasis in 1 regional lymph node
- pN1b = metastases in 2-3 regional lymph nodes
- pN1c = tumour deposit
- pN2 = metastatic disease in 4 or more regional lymph nodes.
- pN2a = metastases in 4-6 regional lymph nodes.
- pN2b = metastases in 7 or more regional lymph nodes.
12
Q
Describe the ‘M’ staging of colorectal cancer.
A
- M = extent of distant metastasis.
- pM1a = metastasis confined to one organ without peritoneal metastases.
- pM1b = metastases in more than 1 organ.
- pM1c = metastases to the peritoneum with or without other organ involvement.
13
Q
What is the prognosis for a patient who has colorectal cancer?
A
- 5 year survival:
- 95% of men and ~100% of women survive stage 1 CRC.
- 80% of men and ~90% of women survive stage 2 CRC.
- 65% of men and women survive stage 3 CRC.
- 25-40% of patients survive stage 4 CRC if the tumour can be surgically removed from the liver.
- 5% of men and 10% of women survive stage 4 CRC.
14
Q
What are the other prognostic factors for a patient with CRC (other than TNM)?
A
- Differentiation (grade) - architecture and specifically gland formation (how closely it resembles a normal gland).
- Tumour deposits - discrete nodules of cancer in the tissue’s lymph drainage area, separate from the primary tumour and with no lymph node or identifiable vascular or neural structures.
- Venous invasion - has it invaded the blood vasculature.
- Lymphatic invasion - has it invaded the lymphatic vessels.
- Perineural invasion - has it invaded the space surrounding a nerve.
15
Q
Describe the pathogenesis of colorectal cancer.
A
- Most CRCs arise from a polyp.
- Progression from a polyp (precursor lesion) to cancer can take 10-15 years.
- Cell of origin is thought to be a stem cell in the base of the colonic crypts.
- Progression is a result from multiple genetic mutations and epigenetic alterations.
-
2 major pathways to neoplastic disease
- Adenoma to carcinoma sequence (chromosomal instability).
- Serrated neoplasia sequence (microsatellite stable or instable).
