Radiation risk from high-LET alpha-emitters using Radium-223 as a model

 

What are we doing?

Radium-223 (²²³Ra) is a radioisotope (radioactive substance) and as it decays it emits alpha-particles. Clinical trials are currently investigating the effectiveness of combining ²²³Ra with other treatments to improve the outcome for prostate cancer patients with bone metastases (cancer tumours that have spread from the prostrate to sites in the bones). ²²³Ra has been shown to effectively target these bone metastases and it is thought this treatment could be used in younger patients with good long-term outlook.

What isn’t clear however, is whether ²²³Ra also affects healthy cells for example, in nearby bone marrow tissue. We are investigating the possibility of unwanted exposure to the DNA in healthy cells with the use of cytogenetic techniques (methods for analysing chromosomes).

Why are we doing this?

We are sampling the blood of prostate cancer patients to make estimates of the dose received from internalised ²²³Ra during treatment. We are using lymphocyte cells found in the blood because lymphocyte cells are exposed as the ²²³Ra circulates to the bone metastases and because, lymphocytes originate from stem cells in the bone marrow. If the bone marrow cells are irradiated (exposed to radiation) the corresponding surviving daughter cells that travel to the blood will also contain a biomarker (evidence for ²²³Ra exposure).

This research is important not only to investigate the clinical effects of ²²³Ra in treated patients but also to understand the cellular effects of ²²³Ra as an internalised alpha-particle emitting radioisotope.

What is the relevance for nuclear test veterans?

This project will produce new data of the cellular effects of alpha-particles emitted by ²²³Ra and its impact, if any, on healthy bone marrow cells in humans. Although there are differences in radiation source and potential route of exposure, we can learn important information on internal dosimetry and delayed cellular effects that may have relevance to internalised long-lived radioisotopes from radioactive fallout material.

What does this research involve?

Lymphocyte cells found in patients’ blood will be analysed for the presence of abnormal chromosomes. These will be assessed for type and frequency of occurrences. These will then be used to estimate the dose received to the circulatory system and, assess for any adverse effects on bone marrow.

What impact might our research have?

This research will improve the understanding of internalised alpha particles for both clinical and radiation protection purposes.