cancer Flashcards
cancer
characterized by uncontrolled and unregulated growth of cells
pathophysiology of cancer
- divide indiscriminately and haphazardly
- proliferate at the same rate as the normal cell tissue from which they originate
3 steps of cancer
- initiation
- promotion
- progression
initiation (step 1) of cancer
mutation occurs in a cell’s DNA leading to activation of oncogenes or inactivation of tumor suppressor genes
promotion (step 2) of cancer
mutated cells undergo continual, unregulated proliferation forming a small cluster of abnormal cells
progression (step 3) of cancer
abnormal cells continue to divide and grow forming a tumor
oncogenes
genes that promote cell growth
benign neoplasm tumors
- well differentiated
- encapsulated
- expansive mode of growth
- metastasis absent
- rarely recur
malignant neoplasm tumors
- usually undifferentiated
- able to metastasize
-infiltrative and expansive growth - frequent recurrence
- moderate to marked vascularity
- rarely encapsulated
- becomes less like parent cell
immunological surveillance
- lymphocytes check cell surface antigens and destroy abnormal cells
- cytotoxic T cells kill tumour cells
- natural killer cells and activated macrophages lyse tumour cells
- B cells produce antibodies directed to tumour surface antigens
immunological escape (mechanisms in which cancer cells evade immune system)
- suppress factors that stimulate T cells
- weak surface antigens allow cancer cells to “sneak through”
- immune system tolerance by some tumour antigens
- suppress immune response from products secreted by cancer cells
- induction of suppressor T cells
- blocking antibodies bind tumour-associated antigens preventing recognition
origin of cancer
- genetic
- chemical
- environmental
- viral or immunological
main sites of metastasis
- brain and cerebro-spinal fluid
- lung
- liver
- adrenals
- bone
anatomical site classification of tumours
- tissue of origin
- embryonal ectoderm (skin, glands)
- endoderm (mucous membranes)
histological classification of tumours
- appearance of cells
- poorly differentiated tumours have a worse prognosis
grade I cancer
- cells differ slightly from normal
- well differentiated