LE 6 – Radiotherapy: Hypoxia and
Radiosensitivity
December 1 st , 2023
Linear accelerator
Radiotherapy
Ionizing radiation
Breaks in DNA
Lot of radicals form in water in cells → indirect effect larger than direct effect.
, Repair or apoptosis
Different cell cycle checkpoints to decide to repair or apoptosis. P53 very important here.
BRCA1 → prone to breast cancer because DNA repair does not work properly.
DNA damage repair foci
See microscopic images containing different
stains.
Foci over time after IR
A lot of damage repaired after already 5 hours
(quick repair). After 24 hours almost all
damage is repaired (slow repair). → See graph.
How cells die after radiotherapy
Most cancer cells die by mitotic catastrophe
after several cell divisions. Tumor cells divide 4
to 5 times before mitotic catastrophe.
Only counting large colonies as measure for surviving
cells. Small colonies, died over time after a couple of
divisions.
Radiosensitivity
December 1 st , 2023
Linear accelerator
Radiotherapy
Ionizing radiation
Breaks in DNA
Lot of radicals form in water in cells → indirect effect larger than direct effect.
, Repair or apoptosis
Different cell cycle checkpoints to decide to repair or apoptosis. P53 very important here.
BRCA1 → prone to breast cancer because DNA repair does not work properly.
DNA damage repair foci
See microscopic images containing different
stains.
Foci over time after IR
A lot of damage repaired after already 5 hours
(quick repair). After 24 hours almost all
damage is repaired (slow repair). → See graph.
How cells die after radiotherapy
Most cancer cells die by mitotic catastrophe
after several cell divisions. Tumor cells divide 4
to 5 times before mitotic catastrophe.
Only counting large colonies as measure for surviving
cells. Small colonies, died over time after a couple of
divisions.
