Neoplasia 1-4 Flashcards
What is a neoplasm?
Abnormal growth of cells that persists after the initial stimulus is removed
What is a tumour?
Any clinically detectable lump or swelling
What is cancer?
Any malignant neoplasm
What is a malignant neoplasm?
Abnormal growth of cells which persists after the initial stimulus is removed AND had the ability to invade surround tissues and has the potential to metastasise to distant non-contiguous sites
What is a metastasis?
Malignant neoplasm that has spread from its original primary site to a non-contiguous secondary site
What is anaplasia?
Poor differentiation of cells resulting in cells which have no resemblance to any other cell histologically
Describe 4 changes that occur in pleomorphism
- Increased nuclear size and nuclear:cytoplasmic ratio
- Increased variation in shape/size of cells/nuclei
- Increased mitotic figures
- Increased nuclear staining (hyperchromasia)
What two alterations in DNA must occur for a cell to become neoplastic?
- Activation of proto-oncogenes
- Inactivation of tumour suppressor genes
What two events are required for neoplasia to occur?
- Initiation (by a mutagenic agent)
- Promotion (causes cell proliferation)
Name 3 common initiators of neoplasia (due to extrinsic factors)
- Chemicals
- Radiation
- Infection
Describe a study which provides evidence that suggests neoplasms are monoclonal
- Study of X linked gene for G6PD deficiency in heterozygous women
- Gene has several alleles encoding different isoenzymes
- One of the alleles is inactivated through lyonisation during female embryogenesis
- Heterozygous women possess tissues which are a patchwork of heat stable and heat labile alleles, however neoplastic cells only express one isoenzyme indicating a monoclonal group of cells
What is the name given to a benign tumour of glandular epithelia?
Adenoma
What is the suffix for a malignant epithelial neoplasm?
-carcinoma
What is a sarcoma?
Malignant neoplasm of stromal tissue cells
What is the name given to a malignant neoplasm of bone?
Osteosarcoma
Why are lymphoid and haemopoietic neoplasms always malignant?
Already present in the circulation, so have the potential to metastasise
Give examples of one benign and one malignant germ cell neoplasm
- Benign - ovarian teratoma/dermoid cyst, seminoma
- Malignant - teratoma of the testes
What is a leiomyosarcoma?
Malignant neoplasm of smooth muscle cells
What is a malignant myeloma?
Malignant neoplasm of plasma cells
Give 3 examples of neuronendocrine neoplasms
- Carcinoid
- Bronchial small cell carcinoma
- Pheochromocytoma of adrenal glands
What is the appearance of a benign neoplasm?
- Smooth surface with pushing outer margin
- Tend to grow in a confined local area
- Cells are well differentiated to surrounding tissue
Describe the appearance of a malignant neoplasm
- Irregular, rough surface with possible ulceration and bleeding
- Invasion of surrounding tissue
- Cells range from well to poorly differentiated
What 3 things must malignant neoplasms do in order to metastasise?
- Grow and invade at the primary site
- Enter a transport system and lodge at a secondary non-contiguous site
- Grow and invade at the secondary site (colonisation)
What alterations must occur in order for a neoplasm to grow and invade surrounding tissue? (3)
- Altered adhesion (decreased expression of E-cadherin and changes in integrin expression)
- Stromal proteolysis (production of matrix metalloproteinases MMPs)
- Motility (signalling by integrins causes changes in the actin cytoskeleton)
What 3 transport systems can malignant tumours enter?
- Bloodstream
- Lymphatic system
- Coelemic spaces via transcoelemic spread
By what method do sarcomas usually spread?
Enter bloodstream
By what method do carcinomas usually spread?
Enter lymphatics, which drain to lymph nodes and can enter bloodstream
What is the greatest barrier to successful formation of metastases?
Failed colonisation at the secondary site
What is the name given to surviving microscopic deposits of malignant neoplasms that fail to grow into clinically detectable tumours?
Micrometastases
An apparently disease free person may harbour many micrometastases. What is this phenomenon called?
Tumour dormancy
What is the most likely cause of a relapse after an apparent cure of cancer?
One or more micrometastases begins to grow
Describe the regional drainage of blood, lymph and coelemic fluid
- Blood drains mainly (but not always) into the next available capillary bed, which tends to be the liver or lungs
- Lymph drains into the regional lymph nodes
- Coelemic fluid spreads to other areas of the coelemic space (transcoelemic spread) or to adjacent organs
What is the “seed and soil hypothesis” and what is its significance?
- May explain the unpredictable distribution of blood borne metastases
- Due to interactions between malignant cells and the local tumour environment (cancer niche)
What is a cancer niche?
- Malignant neoplastic cells and the surrounding healthy cells form a cancer niche
- Malignant cells can take advantage of surrounding non-neoplastic cells in order to grow and invade tissue e.g. by using their growth factors or proteases
What is epithelial->mesenchymal transition?
- Occurs when neoplastic cells (mainly carcinoma) undergo various alterations, such as altered adhesion, stromal proteolysis and motility
- Resulting cells resemble mesenchymal cells rather than epithelia
What are the common sites of blood borne metastases?
- Bone
- Lung
- Liver
- Brain
Which cancers are more likely to metastasise to bone?
- Breast
- Kidney
- Prostate
- Thyroid
- Bronchi
What determines the likelihood of a cancer spreading?
Size of the primary neoplasm (basis of cancer staging)
Why do malignant neoplasms have an increased tumour burden compared to benign neoplasms?
- Have the potential to metastasise and spread to other non-contiguous sites, which has a parasitic effect on the host
- Benign tumours do not metastasise
What are the direct local effects of primary/secondary neoplasms on the host? (4)
- Direct invasion and destruction of normal tissue
- Ulceration and surface, causing bleeding (may lead to anaemia)
- Compression of adjacent structures
- Blocking of tubes and orfices
Name 3 paraneoplastic syndromes of cancer that cause indirect systemic effects on the host
- INCREASED TUMOUR BURDEN (has a parasitic effect on the host; secretion of cytokines can cause cachexia, malaise, immunosuppression and thrombosis)
- HORMONE SECRETION (tumours which are well differentiated can produce hormones)
- MISCELLANEOUS EFFECTS (skin problems, fever, neuropathies, clubbing and myositis)
Name 3 tumours which may secrete hormones and cause indirect systemic effects on the host
- Thyroid adenoma (thyroxine)
- Small cell bronchial carcinoma (ACTH and ADH)
- Squamous cell bronchial carcinoma (PTHrp)
How could a benign tumour affect the host?
- Secretion of hormones as the cells are well differentiated (e.g. Thyroid adenoma secretes thyroxine)
- Compression of adjacent structures
Give 3 intrinsic and 3 extrinsic causes of carcinogenesis
- INTRINSIC - age, gender, heredity
- EXTRINSIC - environment, lifestyle, behaviour
Describe an epidemiological study which shows that the majority of cancer risk is due to extrinsic factors
- Japanese migrants to USA immigration act 1924
- Cancer risk for the Japanese for specific cancers tended towards the cancer risk for specific cancers in the Caucasian American population, showing that extrinsic factors are at play
What lessons were learned about the relationship between exposure and cancer risk from the use of 2-napthylamine in the dye industry? (3)
- There is a long delay between initial exposure and malignant neoplasm onset (factory workers did not develop cancer until decades after being exposed)
- Risk of cancer depends on total carcinogen DOSAGE (increased exposure means increased risk)
- Some carcinogens are specific to particular types of cancer (2-napthylamine is specific to bladder cancer)