A blood sample-based test that assesses the rate of lymphocyte (white blood cell) death after irradiation is currently available in clinical routine. This test assesses the probability of developing late complications after breast or prostate radiotherapy. These two tests (for breast and prostate radiotherapy) are CE marked and have been validated with the highest level of clinical evidence. They are minimally invasive, require a simple blood sample, and provide results within one week.
The Radio-Induced Lymphocyte Apoptosis (RILA) test has been developed to predict the occurrence of late complications, the most worrying radiation side effects. This is a non-invasive test, based on a simple blood sample. The blood sample is irradiated (8 Gy), and then the percentage of lymphocytes (white blood cells) that die due to irradiation is quantified (lymphocyte death rate). The risk of developing late complications is inversely correlated with the lymphocyte death rate. In other words, a patient with high lymphocyte death rate will have a low risk of late complications.
The advantage of this test is that it is non-invasive and provides results within one week, which does not delay treatment initiation.
This test was developed in Switzerland in 1995, and has successfully passed all levels of clinical validation:
- retrospective validation (the test was performed after the patient’s radiotherapy) in a mono-centric study (patients treated in a single clinical center) (1997),
- prospective validation (the test was performed before the patient’s radiotherapy) in a mono-centric study (2005)
- prospective validation in a multicenter study (patients treated at different clinical centers) (2015).
To date, the RILA test is the only technology for radiation sensitivity testing to have reached level I clinical evidence, which corresponds to the highest level of validation for a predictive test of radiosensitivity.
It is now CE marked for breast and prostate cancer and is beginning to be used in clinical routine.