Tumor Response Mechanisms to Stereotactic Radiation Therapy

Stereotactic radiation therapy employs highly conformal beams to deliver ablative doses in few fractions, inducing tumour cell death through complex mechanisms. At high dose per fraction, direct DNA double-strand breaks exceed repair capacity, triggering mitotic catastrophe and apoptosis. Vascular endothelial injury compromises tumour microvasculature, leading to transient hypoxia followed by reoxygenation and vascular maturation that can enhance subsequent dose delivery. Immunogenic cell death releases tumour antigens and danger signals, recruiting cytotoxic T lymphocytes and modulating the immune microenvironment. Genetic heterogeneity within tumour clones governs intrinsic radiosensitivity, while microenvironmental factors such as hypoxia and endothelial-to-mesenchymal transition influence local control. The interplay of DNA damage responses, vascular remodelling and immune activation underpins the superior clinical efficacy of stereotactic regimens compared with conventional fractionation.

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Tumor Response Mechanisms to Stereotactic Radiation Therapy publication trend

The graph below shows the total number of articles in tumor response mechanisms to stereotactic radiation therapy across all publications each year (not limited to Nature Index journals).

Technical terms

Stereotactic ablative radiotherapy (SABR): A technique delivering very high radiation doses in a small number of precise fractions to ablate tumour tissue.

Hypo-fractionation: A regimen in which larger daily radiation doses are given over fewer sessions compared with conventional schedules.

Tumour microenvironment: The complex milieu of stromal cells, vasculature, extracellular matrix and immune components surrounding tumour cells.

Endothelial-to-mesenchymal transition (EndMT): A process by which endothelial cells acquire mesenchymal traits, affecting vessel integrity and tumour regrowth.

Clonogenic survival: The capacity of tumour cells to retain reproductive viability and form colonies after irradiation.

Immunogenic cell death: A form of cell death that stimulates an adaptive immune response through antigen release and danger signal expression.

Vascular maturation: The stabilization of newly formed vessels through recruitment of pericytes and strengthening of endothelial junctions, improving perfusion.

References

1. Ultrafast power doppler ultrasound enables longitudinal tracking of vascular changes that correlate with immune response after radiotherapy. Theranostics (2024).
2. A genetic basis for the variation in the vulnerability of cancer to DNA damage. Nature Communications (2016).
3. Tumour-vasculature development via endothelial-to-mesenchymal transition after radiotherapy controls CD44v6+ cancer cell and macrophage polarization. Nature Communications (2018).
4. Advances in Radiobiology of Stereotactic Ablative Radiotherapy. Frontiers in Oncology (2020).
5. Influence of Radiotherapy Fractionation Schedule on the Tumor Vascular Microenvironment in Prostate and Lung Cancer Models. Cancers (2020).