Analysis of blood and saliva samples to determine the radiation dose during nuclear medicine examinations and treatments

Prostate cancer develops in the prostate, a gland located in the male pelvis that is part of the male reproductive system and produces a portion of the seminal fluid. The thyroid gland is a gland in the neck that produces hormones. Common disorders and abnormalities include, for example, hyperthyroidism, hypothyroidism, or nodules. In both of these groups of conditions, open radioactive pharmaceuticals are used in nuclear medicine. These medications are designed to accumulate in the target tissue and release radiation there, which is either measured externally and used to generate images (nuclear medicine imaging) or intended to damage tumor cells from within (radionuclide therapy). One long-established nuclear medicine procedure is radioiodine therapy, which is used to treat certain thyroid disorders. In prostate cancer, radioactively labeled drugs can be used that bind to a protein typically found in high concentrations on the surface of prostate cancer cells (prostate-specific membrane antigen, PSMA), so that the radiation is directed specifically to the cancer cells. Ionizing radiation primarily damages the genetic material (DNA) of cells, which respond by initiating signaling and repair processes (DNA damage response). In addition, the level of expression of individual genes may change (gene expression). These changes can be detected in blood cells. To date, these changes have primarily been studied in cell samples in the laboratory.

The aim of this observational study is to investigate whether the effects of this radiation can be detected through biological changes in saliva and blood samples (biodosimetry) and to compare these findings with those from physical dosimetry. To this end, saliva and blood samples will be collected at various time points. Samples are collected five minutes before administration of the radioactive pharmaceutical, as well as 20 minutes, four hours, 24 hours, and 48 hours afterward. These samples are analyzed for blood count, gene expression, other genetic changes, and the DNA damage response. The treatment itself is not altered by the study. The study is open-label, which means that both the patients and the study physicians know which test or treatment is being performed.

Patients aged 18 and older with prostate cancer or a thyroid disorder who are deemed by their treating physicians to have a medically justified need for the use of unmasked radioactive substances are eligible to participate. Among others, pregnant and breastfeeding women are ineligible to participate.