Introduction to cancer Flashcards
What is cancer
“A malignant growth or tumour resulting from an uncontrolled division of cells”
abnormal growth of cells caused by faults in the regulation of cell cycle. Damaged cells which should die through apoptosis survive resulting in a malignant growth/tumour resulting from an uncontrolled division of cells.
What is a tumour
simply means swelling
usually refers to a benign/ malignant lesion
What is a Bengign tumour
increase in cell number of normal and healthy cells.
mass of cells that grows slowly and remains localized- may not cause symptoms
Symptoms of a benign tumour
- Pressure resulting from normal function like more hormone production affecting normal bodily function.
- Pressure on surrounding tissues
- Presure due to obstruction of ducts or passage ways
- pressure on skin if formed in a tight space like the skull
what is a malignant tumour
increase in cell number of abnromal and unhealthy cells
symptoms of a malignant tumour
Pressure, loss of function due to growth and invasion of surrounding tissues causing numbeness/ weakness and obstruction of vital structures like GI tract/ production of hromones or cytokines/ disruption of blood supply causing reduced blood flow and death of surrounding tissues. Metastasis in distant organs causing loss of function.
change in bowl habit, irregular bleeding, loss of weight, pain
Features of a benign tumour
Slow growing
Usually encapsulated
Smooth surface
Cells are highly differentiated (resembling normal tissue of origin)
Cells are fairly uniform and resemble each other
features of a malignant tumour
Rapid growth
Irregular tumour surface
No capsule
Tumour destroys the surrounding tissue
Usually causes death if not treated
Tumour cells are usually not as well differentiated
features of benign cancer - blood vessels and DNA
- increased blood vessel formation:timulate the formation of new blood vessels to support their growth (angiogenesis)
- blood vessels in the tumour are well formed
- usually have no necrosis ( cell death due to injury. disease, low blood supply)
- does not metastasise
-DNA content is usually normal - karyotype is usually normal
features of malignant cancer - blood vessels and DNA
- increased blood vessel formation
- blood vessels in the tumour are poorly formed
- usually has some necrosis
- can metastasise
- DNA content is usually abnormal
-karyotype is usually abnormal
What is a tumour? What are the forms ?
Means swelling - increase in size of an organ/area
-can be inflammation, a cyst or a cancer
-can be caused by neoplasia
-can be either benign or malignant
-cancer is always malignant
What is neoplasia?
Neo = new
plasia = growth
Dysplasia
Translates as bad growth
Shows as variation from normal cellular patterns - epithelium classified by structure and function is dependent on this structure
Dysplasia - microscopic features
Pleomorphism (variation in size and shape)
Hyperchromatism(excessive pigmentation)
Presence of excessive mitotic figures - an unusual number of cells which are currently dividing
Also seen as a failure of maturation
Reporting Dysplasia
Some degree of subjectivity
Often double reported - can progress to high grade?
Microscopic assessment of changes is key
Reported as low or high grade dysplasia
Low grade dysplasia features (microscopic )
Enlarged, elongated, crowded nuclei
Shows features of inflammation
More likely to regress
High grade Dysplasia
Pleomorphic, stacked nuclei
Shows features of carcinoma
More likely to progress
Examples of cancer classifications
Carcinoma - Arises from an epithelium - 90% of cancers
Sarcoma- Arises from bone, muscle, cartilage or fat
Melanoma- Arises from melanocytes
Lymphoma - Arises from lymphocytes
Leukaemia - Arises from white blood cells
Causes of cancer
Damage to cellular controls via UV raditaiton, Chemical damage or physical damage. This is caused by sun exposure, pesticides, smoking, poor diet, lack of exercise, infections and obesity.
Cancer is a disease of environment and lifestyle with genetic factors involved. Stress is a big factor but is not casuative
Persistent inflammation leads to cancer.
Predisposing Factors
Age - Most cancers occur in those over 55 years of age
Contrast behaviour of childhood tumours- more aggressive and more likely to be fatal
Genetics
Family history
Familial adenomatous polyposis
Presents as early as teenage, multiple polyps that will become cancerous – removal of colon
BRCA1 & BRCA2 in breast and ovarian cancer
Predisposing pathologies
Ulcerative colitis
Crohn’s disease
Lichen sclerosis
Immunosupression
Environment
Diagnosing Cancer. What type of samples are taken and why?
Sample - biopsy or cytology
dependent on type of cancer suspected, tumour location
biopsy: removal of small piece of tissue from suspected tumor/ abnormal area for microscopic examination. can be needle or incisional. entire tumour can be removed.
biopsy chosen if a solid tumour is acessible for sampling for more infromation about the cell morphology/ characteristics. useful in diagnosing and staging of cancer
Cytology: examination of individual cells from suspected tumour or lesion via fine-needle aspiration to extract cells or brush cytology.
Used when biopsy is difficult or risky or patients not suitable for surgery. can provide rapid diagnostic information about cellular characteristics of the tumour. used for lymph nodes, thyroid, liver, various bodily fluids ( pleural, Cerebospinal)
Diagnosing cancer - What do we see in samples down the microscope?
Hyperplasia
Multiple nucleoli
Hyperchromatic nuclei
Increased nuclear / cytoplasmic ratio
Other microscopic features of tumours include:
-Pleomorphism - variation in size and shape of cells within the neoplasm.
-Abnormal mitoses - highly indicative of malignancy
How is cancer further characterised?
Ki67 proliferation index
