Neoplasia

Question 1

Define neoplasia

Answer 1

The abnormal and unregulated growth of cells forming a mass (neoplasm) due to genetic or epigenetic changes.

Question 2

What are the common characteristics of neoplasia ?

Answer 2

Autonomous Growth - independent of normal regulatory mechanisms.

Irreversible - persists even if the original stimulus is removed.

Classification - benign or malignant.

Question 3

Describe benign neoplasms:

Answer 3

Localized and non-invasive.
Encapsulated with well-differentiated cells.
Slow-growing with minimal mitotic activity.
Examples: Lipoma, Adenoma.

Question 4

Describe malignant neoplasms:

Answer 4

Invasive, capable of metastasis (spreading to distant sites).
Poorly differentiated (anaplasia) and highly mitotic.
Examples: Carcinomas (epithelial origin), Sarcomas (mesenchymal origin), Lymphomas, Leukemias.

Question 5

Describe pre-malignant lesions:

Answer 5

Dysplastic changes with a risk of progression to malignancy.
Examples: Cervical dysplasia, Adenomatous polyps.

Question 6

Describe how genetic changes and epigenetic alterations drive neoplastic transformation:

Answer 6

Genetic changes;
Oncogenes activation - mutations in genes that drive cell proliferation
Tumor supressor genes inactivation - loss of function in genes that regulate the cell cycle or promote apoptosis

Epigenetic alterations:
DNA methylation and histone modification changes that silence tumor suppressor genes or activate oncogenes

Question 7

Describe how environmental factors and cellular processes drive neoplastic transformation:

Answer 7

Cellular processes:

Self sufficiency in growth signals - continuous proliferation
Evasion of growth inhibitors - resistance to anti growth signals
Resisting cell death - avoidance of apoptosis
Sustained angiogenesis - formation of new blood vessels to supply the tumor
Invasion and metastasis - spread of cancer cells to other tissues

Environmental factors;
Carcinogens (e.g., tobacco, UV radiation, chemicals).
Infections (e.g., HPV, Hepatitis B/C).
Chronic inflammation (e.g., ulcerative colitis).

Question 8

Describe different methods for treating neoplastic disease:

Answer 8

Surgical intervention - removal of localised tumours, suitable for benign and early stage malignant

Radiation therapy - uses ionising radiation to kill cancer cells by damaging DNA

Chemotherapy - systemic use of cytotoxic drugs to target rapidly dividing cells

Targeted therapy - drugs designed to target specific metabolic pathways

Immunotherapy - Enhances the immune system to recognize and destroy cancer cells

Hormonal therapy - Targets hormone-driven cancers