Apoptosis in radiation therapy: a double-edged sword

Area of Science:

• Radiation oncology
• Molecular biology
• Cell death pathways

Background:

• Radiation therapy's efficacy relies on inducing apoptosis and non-apoptotic cell death.
• Current radiobiological principles (reoxygenation, repair, redistribution, repopulation) guide fractionated radiation therapy.
• The linear-quadratic model is standard for calculating radiation effects but doesn't explicitly include apoptosis or non-apoptotic cell death.

Purpose of the Study:

• To review cell death pathways relevant to fractionated radiation therapy.
• To explore how molecular understanding of cell death can revise radiobiological principles.
• To assess the role of apoptosis and non-apoptotic cell death in radiosensitivity and tumor characteristics.

Main Methods:

• Literature review of molecular mechanisms of cell death.
• Analysis of existing radiobiological models and their limitations.
• Discussion of the interplay between cell death pathways and tumor biology.

Main Results:

• Apoptosis and non-apoptotic cell death are crucial for radiation therapy's effects.
• The linear-quadratic model does not account for these cell death modes.
• Understanding other cell death forms like autophagy and senescence is advancing.

Conclusions:

• Reassessing the role of apoptosis and non-apoptotic cell death in radiosensitivity is warranted.
• The clinical significance of these cell death pathways depends on tumor type, size, and stage.
• Future research should quantify the impact of dose and fractionation on cell death induction and pathway interactions.