The abscopal effect is a unique phenomenon in cancer treatment that occurs when radiation shrinks untreated tumors found elsewhere in the body in addition to the targeted tumor. The effect has a long history, dating back to the 1950s, but it doesn’t commonly occur in practice and the mechanisms are not fully understood. Research has shown that combining immunotherapy with radiation increases the rate at which the abscopal effect occurs. Understanding how it appears in practice could potentially lead to new cancer treatments and a novel approach to combining immunotherapies with radiation.

Mansoor M. Ahmed, PhD
Mansoor M. Ahmed, PhD, is the program director of the radiotherapy development branch and head of molecular radiation therapeutics in the radiation research program at the National Cancer Institute in Bethesda, MD

To better determine how the immune system interacts with radiotherapy, NCI is bringing together experts from immuno-oncology and radiation to define how each specialty interprets the abscopal effect on the body. Collaboration from vastly different fields is key to the scientific understanding of tumor response at treated and untreated sites during the abscopal effect. As we’re learning more information, we see that the abscopal effect isn’t one single phenomenon but rather many different systems working together in novel ways to attack distant tumor sites by influencing their immunogenicity. More NCI-supported clinical trials are looking at the combination of immunotherapy and radiation in practice to better understand its dosing, sequence, and effects.

To study the full effects of the abscopal effect, researchers need rigorous laboratory science to back up the data observed in clinical settings. NCI working groups are creating a systematic approach for research to enable the community to gather the best evidence base to inform practice. As the working groups collaborate, we hope they will find that combining radiation and immunotherapy will trigger the abscopal effect and allow clinicians to exploit the impact of immunotherapy more robustly and improve patient response.

Although research is still in the early stages, oncology nurses will be at the front lines for symptom management and patient education as novel therapies are approved. The potential to harness the abscopal effect through combination immunotherapy and radiation means that nurses will need a dedicated knowledge of side effects associated with both types of treatment, how adverse events overlap, and the best interventions to ensure patients maintain an acceptable quality of life.

The knowledge and science for the abscopal effect may still be years from daily practice, but quality cancer care starts with a fundamental understanding of the standards of care—for both immunotherapy and radiation. National organizations like ONS can help further the knowledge and research associated with immunotherapy and radiation combination treatments by providing practicing nurses with the education and resources they need.