Neoplasia

Question 1

What is neoplasia?

Answer 1

Excessive and unregulated cell proliferation

- results from aberrant genetic and epigenetic control mechanisms affecting the cell cycle, apoptosis and DNA repair

Question 2

What are the differences between benign and malignant?

Answer 2

Benign

• local expansile with generally slow growth, often well circumscribed
• well differentiated cells (look fairly normal)
• unable to metastasise
• rarely life-threatening

Malignant

• locally invasive, destructive growth, often poorly circumscribed
• potential to metastasise
• variable differentiation
• sometimes necrosis
• frequently induce desmoplasia in stroma as they invade

Question 3

What are the histopathological features of neoplasia?

Answer 3

Cytological atypia 
- larger nuclei 
- pleomorphic nuclei 
- coarser nuclear chromatin 
- hyperchromatic nuclei 
- larger, more prominent nucleoli 
- more mitotic activity 
Architectural disorganisation 
* benign neoplastic cells generally show less atypia than malignant cells

Question 4

What does the grade of a tumour refer to?

Answer 4

The degree of differentiation of a malignant tumour

Question 5

What is invasive neoplasia?

Answer 5

• cells lose their cohesiveness, cell junctions not functioning normally, invade the epithelium, produce angiogenic factors

Question 6

What are the 4 classes of normal regulatory genes that are involved in cancer?

Answer 6

• growth-promoting proto-oncogenes
• growth-inhibiting tumour suppressor genes
• genes that regulate apoptosis
• genes involved in DNA repair (microsatellite instability)

Question 7

What is loss of heterozygosity?

Answer 7

LOH in a cell represents the loss of normal function of one allele of a gene in which the other allele was already inactivated

Question 8

What is p53?

Answer 8

A tumour suppressor gene which regulates the expression of cell cycle factors

• cellular responses are: apoptosis, cell-cycle arrest, DNA repair, differentiation, senescence
• • these are defective when p53 is mutated or deleted

Question 9

What happens to the cell cycle during cancer?

Answer 9

Loss of proliferation control via oncogenic activation and TSG inactivation leads to loss of cell cycle control

Question 10

What do telomeres do?

Answer 10

Protect against degradation of chromosomes

Question 11

What is the stage of cancer?

Answer 11

The progression the malignancy has made in terms of local spread and metastasis
- incorporates the size or depth of invasion, local extent of primary tumour, location and extent of metastases