A new study has revealed that certain bone marrow cells may absorb more radiation during radiopharmaceutical therapy (RPT) than previously believed. This finding could explain unexpected side effects like reduced blood cell counts that some neuroendocrine cancer patients experience.
Radiopharmaceutical therapy has become a promising cancer treatment, using imaging to guide therapy and adjust doses for each patient. This approach helps doctors visualize how the treatment spreads through the body and calculate safe levels of radiation for organs.
However, a recent study shows that this imaging might not capture the full picture. A research team led by Susanne Kossatz, PhD, of the University Hospital Klinikum rechts der Isar at Technical University Munich, found that key cells in the bone marrow—hematopoietic stem cells (HSCs), which are vital for producing all types of blood cells—can absorb higher levels of radiation, even when overall doses appear safe.
The researchers used specialized fluorescent versions of drugs typically used to treat neuroendocrine tumors and tracked how these drugs attached to specific types of bone marrow cells. They discovered that some cells take up the drugs at levels similar to tumor cells.
“In theranostics, we follow the paradigm that “what we see is what we treat,” said Dr. Kossatz, whose research was funded in 2020 through a collaborative grant from NETRF and The Education and Research Foundation. “Here, we uncovered a case where the treatment unintentionally affected a critical cell population that could not be seen in standard imaging studies, resulting in ‘sometimes we do not see what we treat.’”
The study’s findings, available in a preprint, suggest that relying solely on imaging data could underestimate the risks of certain therapies. The investigators recommend a more cautious approach when introducing new radiopharmaceutical treatments, including careful dose adjustments during the initial phase of therapy. This could help reduce side effects and ensure better outcomes for patients by better predicting how these drugs interact with the body at a microscopic level.
For patients with neuroendocrine tumors, these insights emphasize the importance of thorough monitoring and tailored treatment plans. While RPT remains a powerful option in the fight against cancer, understanding how the therapy interacts with the body can help enhance its safety and effectiveness.