Radiosensitivity
Radiation therapy
More than 50% of patients with cancer will receive radiation therapy in their treatment care pathway.
Radiation therapy is a localized treatment that delivers ionizing radiation to cancer cells to kill them. The beam of radiation will be targeted to the area where cancer cells are present. However, the nearby normal tissues will also be exposed.
In some patients, the unwanted irradiation of normal tissues can lead to irreversible side effects. These side effects are called « late toxicities » or « late complications » because they occur after the treatment end. It is estimated that 5 to 10% of patients treated with radiotherapy will develop late toxicities [1, 2].
50% of cancer patients will be treated by radiotherapy.
5 to 10% of these patients will develop late toxicities.
Why to do a novagray test?
For more than a century, radiobiology researchers have investigated the normal tissue sensitivity to ionizing radiation and found that it varies among patients, and that each person has a different tolerance threshold [3].
In almost 30% of patients, the risk of developing late toxicities in normal tissues is higher than in the average patient [4]. However, only 5 to 10% of these patients, defined as hypersensitive, will actually develop late complications [5, 6].
Identifying the patients at risk of side effects before starting radiation therapy is essential to optimally adapt their treatment.
Hypersensitive patients will develop late toxicities
5-10% of patients
Patients who will not develop late toxicities
90-95% of patients
The efficacy of radiation therapy depends largely on the dose delivered to the tumor: higher doses will lead to better tumor control and higher chances of cure.
However, higher doses also increase the risk of side effects. Therefore, this dose cannot exceed the patient’s tolerance threshold to limit the risk of late side effects.
Towards a personalized radiotherapy
A major challenge in clinical radiobiology is to predict the radiosensitivity level of each patient in order to propose a tailored treatment, adapted to each patient.
This is precisely the objective of the tests developed by NovaGray.
REFERENCES
1. Barnett GC, West CML, Dunning AM, et al. Normal tissue reactions to radiotherapy: towards tailoring treatment dose by genotype. Nat Rev Cancer 2009 ; 9 : 134-42.
2. Bentzen SM, Constine LS, Deasy JO, et al. Quantitative analyses of normal tissue effects in the clinic (QUANTEC): an introduction to the scientific issues. Int J Radiat Oncol Biol Phys 2010 ; 76 : S3-9.
3. Holthusen H. Erfahrungen über die verträglichkeitsgrenze für röntgenstrahlen und deren nutzanwendung zur verhütung von schäden. Strahlentherapie (1936) 57:254–69.
4. Azria D, Riou O, Castan F, et al. Radiation-induced CD8 T-lymphocyte apoptosis as a predictor of breast fibrosis after radiotherapy: results of the prospective multicenter French trial. EBioMedicine 2015 ; 2 : 1965-73.
5. Emami B, Lyman J, Brown A, et al. Tolerance of normal tissue to therapeutic irradiation. Int J Radiat Oncol Biol Phys 1991 ; 21 : 109-22.
6. Bentzen SM, Constine LS, Deasy JO, et al. Quantitative analyses of normal tissue effects in the clinic (QUANTEC): an introduction to the scientific issues. Int J Radiat Oncol Biol Phys 2010 ; 76 : S3-9.
7. Barnett GC, West CML, Dunning AM, et al. Normal tissue reactions to radiotherapy: towards tailoring treatment dose by genotype. Nat Rev Cancer 2009 ; 9 : 134-42.
8. Barnett GC, West CML, Dunning AM, Elliott RM, Coles CE, Pharoah PDP, et al. Normal tissue reactions to radiotherapy: towards tailoring treatment dose by genotype. Nat Rev Cancer (2009) 9:134. doi:10.1038/nrc2587.
