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Updated: May 26, 2026

Proton Therapy Delivery and Its Clinical Application in Select Solid Tumor Malignancies
Published on: February 6, 2019
Maximizing tumor immunity with fractionated radiation.
Dörthe Schaue1, Josephine A Ratikan, Keisuke S Iwamoto
1Department of Radiation Oncology, David Geffen School of Medicine at UCLA, B3-109 CHS, 10833 Le Conte Avenue, Los Angeles, CA 90095-1714, USA. dschaue@mednet.ucla.edu
Radiation dose and fraction size significantly impact antitumor immunity and tumor control. Optimal fractionated doses enhance anti-tumor responses while minimizing suppressive immune cells, suggesting radiation can act as an immune adjuvant.
Area of Science:
- Radiation oncology
- Immunology
- Cancer research
Background:
- Technological advancements enable higher radiation doses and fractions in cancer treatment.
- The effects of radiation dose and fraction size on antitumor immunity and normal tissue responses are not fully understood.
Purpose of the Study:
- To investigate how radiation dose and fraction size influence antitumor immunity.
- To explore the impact on immune suppression and its relation to tumor control.
Main Methods:
- Mice with B16-OVA melanoma were irradiated with varying doses and fractions.
- Tumor growth was monitored.
- Splenic immune responses, including interferon-γ ELISPOT and regulatory T cell (Treg) populations (CD4(+)CD25(hi)Foxp3(+)), were analyzed.
Main Results:
- Single high-dose radiation improved tumor control and T cell response but increased Tregs.
- Fractionated radiation (7.5 Gy/fraction) yielded the best tumor control and immunity with low Treg levels.
Conclusions:
- Radiation dose per fraction size critically affects the immune response.
- Radiation can serve as an immune adjuvant.
- Optimizing the integration of immunotherapy with radiation therapy is crucial.
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