Properties of Malignant Cells Flashcards
What are the 6 ‘Hallmarks of Cancer’?
> Self-sufficiency in growth signals > Evading anti-growth signals > Evading apoptosis > Limitless replication potential > Tissue invasion and metastasis > Sustained angiogenesis
What is the key difference in the growth of malignant tumours vs benign tumours?
Benign grow by expansion, whereas malignant grow by invasion and expansion
What suffix is given to benign tumour names?
- oma
e. g. adenoma, myoma
What suffix is given to malignant tumour names?
- carcinoma, -sarcoma
e. g. adenocarcinoma, myosarcoma
What are some key histological features of benign tumours?
> Few mitoses
Normal/slight increase nuclear:cytoplasmic ratio
Cells tend to be uniform throughout the tumour
Resemble cell/tissue of origin (often well differentiated)
What are some key histological features of malignant tumours?
> High nuclear:cytoplasmic ratio
Many mitoses (highly proliferative)
Cells vary in shape/size throughout the tumour (pleomorphism)
Fail to differentiate fully
How can a benign tumour possibly become a malignant cancer?
Benign tumour cells are predisposed to becoming malignant due to their cells already suffering an initiating mutation/event, which led them to become a benign growth in the first place. Subsequent mutations could lead to further loss of TSGs/gain of oncogenes, leading to the cells acting in a more malignant fashion.
Normal cell –> Initial mutation –> Abnormal cell, 1 mutation (which divides) –> Benign hyperplasia –> Second mutation –> Abnormal cell, 2 mutations (which divides) –> Carcinoma in situ –> n number of mutations –> Invasive cell (with n number of mutations) divides and becomes invasive carcinoma
What are the 3 stages of tumour progression?
1.Initiation – an event that alters the genome
2.Promotion – an event that causes
proliferation of the transformed cell, giving
rise to a neoplasm
3.Progression – new genetic mutations occur,
with development of sub-clones of cells
N.B. Benign tumours have already achieved stage 1/2
What is the role of cancer stem cells in tumour progression?
Normal stem cells give rise to progenitor cells. These progenitors undergo rapid cell division to replace cells which may have been lost (through apoptosis or other means).
In cancer, a mutation within the stem cells or their progenitors leads to a mass expansion of cells containing that mutation, often leading to them not becoming fully differentiated (neoplastic). This often happens many times within a tumour and the tumour acquires many ‘sub-types’ of cells (tumour heterogenecity).
The cells with mutations beneficial to their survival survive (through natural selection) and proliferate further, leaving the most resilient cells and making the tumour more resilient and aggressive in nature.
What is Tumour Grading?
Grading often refers to the degree of cellular differentiation within a tumour. Dependent on histological evidence.
What is Tumour Staging, and what system(s) are frequently used?
Staging is a measure of the extent of the disease on a more systemic level. The TNM staging system is most commonly used (or Duke’s in Colorectal).
What do the individual components of TNM mean?
T - Tumour; size/extent of tumour
N - Nodes; degree of spread to regional lymphatics
M - Metastasis; presence of distant metastatic tumours
