Oncology Flashcards
indications for chemotherapy
- chemo-sensitive tumours
- primary therapy for haemopoietic malignancies (lymphoma)
- adjunctive therapy for solid tumours
why we don’t use chemo for treatment of solid tumours
- acts on rapidly dividing cells
- cells in resting phase of cell cycle (G0) are most resistant to chemo
treatment options for lymphoma
- single agent prednisolone (MST 2-3 months)
- single agent doxorubicin (MST 6-9 months)
- COP (6-9 months, 70-80% remission)
- CHOP (MST 12 months, 75-90% remission)
CHOP multi agent protocol
Cyclophosphamide
Hydroxydaunorubicin
Oncovin
Prednisolone
dangers of chemotherapy
- chemo drugs can be found in urine, saliva and faeces
- drugs are mutagenic, abortifacient, teratogenic and carcinogenic
safe handling of chemo
- PPE
- closed system of administration (luer-lock syringe)
- use of plastic pad (inco sheet)
- use of chemo room
- allocated bins
- no pregnant women handling drugs
effects on GI tract from chemo
- death of rapidly dividing cells can increase risk of sepsis due to loss of mucosal integrity
- vom, diarrhoea, nausea
effects on bone marrow from chemo
- low WBC count leads to susceptibility to infections
- low RBC leads to anaemia (low platelets)
how to make perivascular injection of chemo drugs less likely?
- flush catheter
- appropriate restraint
- highly visible injection sight (unwrap bandage)
- use catheter (don’t go off needle)
- clean stick catheters only (no repeated attempts on one vein)
side effects of chemo on organ systems
- renal
- cardiac
- hepatic
- urinary (cystitis symptoms)
- dermatological (perivascular admin)
cancer definition
persistent, purposeless proliferation of host cells, detrimental to the host
6 necessary features of neoplasia
- evading apoptosis
- self-sufficiency in growth signals
- insensitivity to anti-growth signals
- tissue invasion and metastasis
- limitless replicative potential
- sustained angiogenesis
local behaviour of malignant tumour
- diffuse, indistinct boundaries
- fixation of tumour in one or more planes
- thickening of adjacent tissue
- spontaneous bleeding or ulceration
metastatic potential
- ability to spread to distant tissues is a feature of malignancy
spread may be: - via blood
- via lymphatics
- transcoelomic (across pleura)
- iatrogenic
what are paraneoplastic syndromes (PNS)
- arise from production and release of biologically active substances
- can affect distant organs
- can develop before or after diagnosis of cancer
what is haematological PNS
- changes in RBC, WBC and platelet counts occurring with neoplasia
- anaemia, thrombocytopenia
mechanisms for paraneoplastic anaemia
- myelopthisis- invasion of bone marrow by neoplastic cells
- haemorrhage- some neoplasia bleeds, some are severe enough to cause hypovolaemia
- immune-mediated haemolytic anaemia- reactivity between cancer and RBC causes destruction of RBC
- anaemia of chronic disease- due to disordered iron handling
hyperviscosity syndrome
- due to anything that makes the blood more sludgy
- increased blood cell numbers (erythrocytosis, polycythaemia)
- excessive production of gamma-globulins
hyperhistaminaemia
- some tumours release histamine and vasoactive amines
- this can be responsible for signs local to the tumour: swelling, erythema, pruritus
- or signs away from the tumour: GI ulcers
- anaphylactic shock is possible if huge, sudden release of histamine
immune mediated PNS
- due to reactivity between cancer cells and healthy cells
- immune-mediated thrombocytopenia
- immune-mediated haemolytic anaemia
- myaesthenia gravis
endocrine related PNS
- endocrine tumours and non endocrine tumours can produce hormones
- clinical signs are dependant on the hormone that is excessively produced
pyrexia as PNS
- thought to be due to production of cytokines by neoplasm
- other causes of pyrexia should be ruled out first
cachexia
- loss of fat and muscle in patients with cancer
- despite adequate nutritional intake
- thought to be due to production of cytokines by neoplastic cells
aims of investigating cancer
- histological/cytological diagnosis
- determine extent of local and distant spread
- investigate and treat tumour-related complications
- patients ability to tolerate therapy
- determine prognosis
diagnosing cancer
- history
- physical exam
- lab testing
- imaging
- biomarkers (unreliable)
- biopsy (cytology, histopathology)
biopsy: cytology samples
- collects individual cells or small clusters
- can be collected through:
- touch/impression preps (moist lesions)
- FNAs- fine needle aspirates
- cytospins of body fluids/effusions
biopsy: histology samples
- collects whole pieces of tissue
- more invasive than cytology
- allows tumour grading
- incisional or excision
tumour grading
microscopic quantification of parameters that correlate with the clinical aggressiveness of a neoplasm based on the tumours architecture
- invasion of adjacent tissues?
- evidence of metastasis? (presence of neoplastic cells in blood vessels)
5 rules of incisional biopsy
- avoid superficial ulceration, inflammation or necrosis
- ensure adequate depth
- try to include a boundary between tumour-normal tissue
- do not predispose to local tumour recurrence or dissemination (spread of neoplastic cells into the body)
- do not compromise subsequent therapy
when is excisional biopsy indicated?
- when incisional biopsy is too dangerous (tumour in lungs can cause pneumothorax)
- if knowledge of tumour type and grade doesn’t change treatment approach (bleeding splenic tumour)
clinical staging
- determines extent of neoplastic disease for therapy and prognosis
considers: - histological grade
- local invasion
- metastatic spread
All 4 views of inflated thorax should be radiographed prior to any treatment
TNM staging system
T- tumour- size and invasiveness
N- nodes- assessing drainage for evidence of spread
M- metastasis- assessing spread to other organs
aims of cancer treatment
- cure- all cells with capacity for tumour regeneration are eradicated
- remission- cancer had disappeared but cells remain and will relapse over time
- palliation- reduce pain, improve quality of life, correct physiological malfunction
surgical excision of tumour
- primary objective is to remove all tumour cells
- more aggressive a malignancy is, the wider the excision margins will need to be
- insufficient margins will leave satellite cells leading to tumour regrowth
intracapsular resection (debulking)
- mass excised within their capsule leaving behind neoplastic tissue
- recurrence will occur unless followed with adjunctive therapy
- incurable malignant neoplasia of vital structures (mouth, CNS)
post-op complications
failure of surgery occurs when:
- regrowth at primary site due to incomplete resection
- already metastasised
- tumour is systemic (lymphoma)
radiotherapy
- external beam radiation therapy, brachytherapy
- causes ionisation, damaging DNA within cells causing cell death
- radiation needs to given to neoplastic tissue only to prevent damage to healthy cells
when is radiotherapy an option
- primary tumours with no metastasis but cannot be controlled with purely surgery due to size or site
- oral or nasal cavity, CNS tumours
