treatment of cancer Pt1 Flashcards
in radiation what is DNA showered with
photons
2 ways photons can act on DNA
direct action
indirect action
direct action of a photon=
photon expels an electron from the molecule which directly damages the DNA
indirect action of a photon=
causes free radical generation which then damages the DNA
what molecule does indirect action require
oxygen
what type of tumour doesn’t respond well to radiotherapy
hypoxic tumours
what happens to a cell when it undergoes a lot of damage
apoptosis
2 types radiotherapy
external
internal
external radiotherapy=
external beam radiotherapy
internal radiotherapy
brachytherapy
4 types of external radiotherapy
conventional
stereotactic
particle
3-D conformal
how is conventional radiotherapy delivered
two-dimensional beams using kilovoltage high energy X-rays
what can limit conventional radiotherapy
radiation toxicity to near by healthy tissue
what is stereotactic radiation
uses focused beams targeting a well defined tumour using detailed CT scanning
what type of tumour is stereotactic used for
small tumours
what is particle radiation
using energetic ionizing particles directed at the tumour
benefit of particle radiation
less energy deposited into healthy tissue
what is 3-D conformal radiotherapy
the profile of each beam is shaped to fit the profile of the target using a multileaf collimator
what does 3-D conformal radiation allow
higher dose of radiation to be delivered to the tumour
what is brachytherapy
radiation source inside or next to the area requiring treatment
2 stages of reaction to radiotherapy
acute tissue reaction
late tissue reaction
5 acute side effects of radiotherapy
- epithelial damage
- mouth, throat, stomach sores
- intestinal discomfort
- swelling of soft tissue
- infertility
4 late side effects of radiotherapy
- fibrosis
- hair loss
- dryness
- lymphedema
xerostomia=
dry mouth
what causes xerostomia
injury to acinar cells
what is chemotherapy
cytotoxic drugs which affect rapidly dividing cells
4 chemotherapy treatment strategies
curative
adjuvant
neoadjuvant
palliative
curative chemotherapy=
used to permanently cure patients e.g acute leukaemia
where do most chemotherapy drugs work
Cell cycle
what stage of division can a lot of tumour cells stay in (which leads to treatment resistance)
G0 - resting phase (treatment doesn’t always target this stage)
what is adjuvant chemotherapy
given after radiotherapy or surgery so less chemo needed
e.g 3 of adjuvant chemo
breast cancer
lung cancer
colorectal cancer
what is neoadjuvant chemo
give pre surgery to downstage tumour before removing it
e.g of 3 neoadjuvant chemo
bladder
breast
head and neck
palliative chemo focus=
relief from symptoms
what is the effect of acute toxicity on chemotherapy
self limiting due to effect on normal proliferating cells
what is the effect of long term toxicity from chemo
end organ damage
what are healthy cells chemio affects
bone marrow
hair follicles
GI mucosa
skin
3 common side effects of chemo
- decreased WBC, RBC, platelets
- alopecia
- stomatitis/ mucositis
4 organs affected by chronic chemotherapy toxicity
lung
heart
CNS
Endocrine
what may increase in expression in cytotoxic drug resistance
MDR-1 gene
what is MDR-1 gene involved in
drug efflux
3 drugs that can reverse MDR
verapamil
quinidine
cyclosporine
