Oncology Flashcards
define cancer
persistent, purposeless proliferation of host cells, often to detriment of host
what are different behaviours cancers can show?
benign
highly malignant
metastasis
list features of cancer
evading apoptosis self sufficiency in growth signals insensitive to anti-growth signals sustained angiogenesis limitless replicative potential tissue invasion and metastasis
what is the cause of cancer?
alteration of genes
what changes to genetics lead to cancer?
overactive oncogens which are tumour promoting
loss of tumour suppression genes
how are cancers named?
tissue of origin
status- benign or malignant
define metastasis
development of tumour away from primary tumour
define benign
neoplasm that forms solid cohesive tumour without metastasis
define malignant
neoplasm with capacity for local invasion and metastasis
list clinical features of cancer
effect on host
response to treatment
reflection of tumour growth, grade and behaviour
what is meant by tumour behaviour?
local behaviour
metastatic and PNS effects
why are most cancers advanced before they are detected?
most of growth has taken place before this time
when can tumours be detected?
1cm diameter
1g weight
10^9 cells
define growth fraction
proportion of actively dividing cells which determines tumour growth
define tumour
swelling inferred to be neoplastic
why are tumours susceptible to treatment when in early stages?
tumour cells are rapidly dividing so sensitive to chemo and radiation
what determines response to chemo and radiation?
growth fraction
why is treatment likely to be toxic for treating detectable tumours?
growth fraction reaching plateau so tumour is less susceptible than rapidly dividing healthy tissues such as intestinal epithelium and bone marrow
what makes tumours heterogenous?
cancer cells modify properties as they grow by small sequential mutations
what determines tumour grade?
mitotic rate
cellular and nuclear characteristics
how does rate of growth differ between benign and malignant tumours?
benign- slow
malignant- rapid
describe how benign and malignant tumours grow in space
benign- expansive with well defined boundaries
malignant- invasive with poorly defined boundaries
which type of tumour has often serious effects on adjacent tissues?
malignant
what is the effect of surgery on benign and malignant tumours?
benign- curative with complete resection
malignant- curative if complete resection and no mets
which tumour type has potential to metastasise?
malignant
when can benign tumours be dangerous to the host?
if causes bleeds
located in vital organ
which types of tumour can cause paraneoplastic effects?
benign and malignant
how do malignant tumours grow?
local invasion and may extend microscopically into surrounding tissues
list indicators of local invasion
diffuse and indistinct boundaries
fixation of tumour in one or more planes
thickening of adjacent tissue
spontaneous bleeding
what is meant by metastatic potential?
ability to spread to distant tissues
list ways of metastatic spread
blood
lymphatics
transcoelomic across pleural or peritoneal space
iatrogenic
what is the effect of metastasis via blood?
secondary tumours can form in any body cavity
how does cancer metastasise via lymphatics?
spreads to local then regional lymphnodes
what are examples of iatrogenic spread?
biopsies and seeding
where is the most common site for secondary tumours to develop?
lungs
name common places for secondary tumours to develop and why
liver spleen kidneys bone CNS high blood flow
define paraneoplastic syndrome/PNS
signs from indirect effect of tumours production and release of biologically active substances
what is the impact of PNS?
may be first evidence of neoplastic disease
may be life threatening before cancer kills patient
list the types of hematologic PNS and signs of these
anaemia- weakness, lethargy, tachypnoea
thrombocytopenia- bleeding
leukopenia- susceptible to infection
what is hyper viscosity syndrome?
PNS with increased blood cell numbers with sludging blood and poor circulation
list causes of hyper viscosity syndrome
primary polycythaemia
leukaemia
excess gamma globulins
secondary polycythaemia due to excess erythropoietin secretion
what are clinical signs of hyper viscosity syndrome?
lethargy tremors thromboembolism bleeding ataxia seizures
what causes hyperhistaminaemia PNS?
mast cell tumours often release histamine and vasoactive amines
what are local affects of hyperhistaminaemia?
oedematous swelling with erythema and pruritis
tendency for localised bleeding due to heparin release
delayed wound healing, dehiscence after surgery due to released proteases
what are systemic effects of hyperhistaminaemia?
anaphylactic shock
what is meant by immune mediated reactions due to PNS?
cross reactivity between cancer and healthy cells
what causes endocrine related PNS?
non-endocrine tumours release hormones or hormone like substances which have paraneoplastic effects
what causes hypercalcaemia PNS?
tumours release parathormone-like substance increasing total and ionised calcium concentration
what types of cancer most commonly causes PNS hypercalcaemia?
lymphoma
myeloma and carcinoma with skeletal metastasis
what are clinical signs of hypercalcaemia?
PUPD anorexia vomiting lethargy depression muscle weakness bradycardia renal effects and failure
how does hypoglycaemia PNS happen?
pancreatic insulinoma produces insulin
release of insulin like factor called leiomyoma
excess glucose consumption
what causes cancer cachexia PNS?
abnormal metabolism due to enhanced catabolism
reduced food intake
what causes fever PNS?
pyrogens
cytokines
what are the aims of cancer investigations?
make histological diagnosis of type and grade
determine stage of disease
investigate and treat tumour related or other complications
state investigations carried out for cancer diagnosis
history physical exam lab testing imaging biopsy for cytology and histopathology
what is the only way to accurately diagnose cancer?
microscopic exam of tissue or cells
how can you produce samples for cytology?
touch/impression preparations
fine needle aspirations
samples of effusion or body fluid in EDTA tube
define neoplasia
new growth, inferring abnormal growth
what are negatives of cytology samples for cancer diagnosis?
may not be definitive diagnosis
false negatives possible
can be hard to differentiate inflammation and neoplasia
what can be shown by large biopsies of tumours?
cellular features of malignancy
tumour architecture
invasion of adjacent tissues
evidence of metastasis
define incisional biopsy
small piece of tumour taken with some healthy tissue for comparison
define excisional biopsy
whole tumour including margins removed
how can you provide a representative sample of a tumour for biopsy?
avoid superficial ulceration, inflammation or necrosis
ensure adequate depth
include boundary between tumour and normal tissue