Cancer Flashcards
A definition of cancer
Cancer is a term used for diseases in which abnormal cells divide without control and are able to invade other tissues. Cancer cells can spread to other parts of the body
Kinds of benign neoplasias
Hyperplasia
Metaplasia
Dysplasia
Adenomas/polyps/warts
Hyperplasia
Over proliferation of cells that appear otherwise normal
Metaplasia
Normal in appearnace but in the wrong place, usual from an adjacent tissue
Dysplasia
Cells that appear abnormal; often increased nuclear to cytoplasmic ratio
Adenomas/polyps/warts
Larger growths of dysplastic cells
Driver mutations vs Passenger mutations
driver mutations do affect function of genes that reegulate proliferation, apoptosis, immortality
Passenger mutations are ones not relevant to promotion of cancer
Function of proto-oncogenes
Promote cell proliferation
Gain of function mutations in cancer
Function of tumour supressor genes
Inhibit events leading to cancer
Loss of function mutations in cancer
Main characteristics of cancer
Proliferation: grow independantly of signals
Immortality: Avoid senescene/telomere shortening
Avoid cell death: Avoid apoptosis
Angiogenesis: They must be fed
Metastasis
At which cell cycle checkpoint do oncogenes work
Restriction point
Which two processes normally limit life of cell
Senescence: Cells in G0, dont proliferate
Apoptosis: programmed cell death
Define senescence
- Metabolically active, irreversibly lost ability to re-enter cell cycle, stay in G0
- Normal cells have finite proliferative capcity (Hayflick limit)
- Cancers must avoid senscence to continue growing
Role of P53 in Telomeres/cancer
P53 normally warns about short ends and initiates senescence
Excess telomere shortening leads to crisis and apoptosis
Crisis
- Normall cells will undergo apoptosis
- In cancer cells TERT is reactivated; repairs broken ends, but creates faulty chormosomes
Which factor induces angiogenesis
Hypoxia-inducible factor 1-alpha is a hypoxia induced factor
Different word for tumour
Neoplasia
Define neoplasia
An abnormal mass of tissue, the growth which exceeds, and is uncoordinated with, that of normal tissue, and which presents in the same excessive manner after the cessation of the stimulus which has evoked the change
Cancer is colloqial speak for
A malignant tumour
Meaning of differntiation in tumours
Described how close in appearance the cells of a tumour are to the cell type from which they are derived. Important in predicting likely behaviour of a tumour
Different tumour types based on differentiation
Well-differentiated
- Composed of cells which very closely resemble the cell of origin
Poorly differentiated
- Bear little resemblance to the cell of origin, but just enought for original cell type to be indentified
Undifferntiated/Anaplastic tumour
- Composed of cells which are so undifferntiated that cell of origin is unknown
Benign vs Malignant tumours
Benign
- Grow by expansion
- Compress adjacent tissue
- DO NOT infiltrate/spread
Malignant
- Grow by expansion AND INFILTRATION
- Compress and invade adjacent tissue
- INFILTRATE
- Can spread to different sites = metastasis
Define Adenomas
Tumour of glandular epithelium
Define Papilloma
Tumour of squamous and transitional epithelium
Define Carcinoma
A malignant epithelial tumour
Suffix for benign mesenchymal tumuors
- OMA
e. g. osteoma, lipoma
Suffix for malignant mesenchymal tumours
- OSARCOMA
e. g. osteosarcoma
Liposarcoma
Define Teratomas
Tumours derived from ferm cells, containin representatives from all 3 germ layers
Difference in benign tumour growth in solid organs vs epithleium
Solid organs
Expand, compress adjacent tissue. Look circumscribed and give a spherical mass
Epithelial surfaces
Form papillary outgrowths in directino of least resistance=papilomas
Cytological characteristics of malignancy
- High nucleus to cytoplasm ratio
- Pleomorphism
- Nuclear hyperchromatism
- High mitotic count
- Abnormal mitoses
Cellular vs nuclear pleomorphism
Variation in size/shape of tumour cells
vs
Variation in size/shape of nuclei in tumour cells
What is a high mitotic count
Increasednumbers of cells in mitosis, including abnormal mitotic forms
Indicative of malignancy
Define Dysplasia and its causes
Abornam cell structure, due to:
- Loss of differntiation
- Pleomorphism
- Nuclerar hyperchromatism
- High nucleus/cytoplasm ratio
Carcinoma in-situ
A dysplastic epithelium showing cytological characteristics of malignancy but no evidence of invasion
Modes od spreak for malignant tumours
Lymphatics, transported to node, can proliferate within nodes
Blood stream, Clumps break off and enter circulation, can cause tumour embolisms and procue a distant metastasis
Effects/problems from benign tumours
Not alway harmless, can cause illnes and death by:
- Bleeding e.g. gut, bladder
- Pressure on adjacent vital structures e.g. in brain
- Obstruction e.g. in brain, bronchus
- Hormone secretion e.g. pituitary adenoma
- Conversion to malignant tumour