RADIOSENSITIVITY
RADIOTHERAPY
More than 50% of patients with cancer will receive radiation therapy in their treatment care pathway.
Radiotherapy is a localized treatment that kills cancer cells by delivering ionizing radiation. Although targeted at cancer cells, the beam of radiation inevitably affects nearby normal tissue.
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.
HYPERSENSITIVITY TO IONIZING RADIATION
For over a century, work in radiobiology has shown that sensitivity to ionizing radiation is individual, with each person having his or her own tolerance threshold [3].
As a result, around 30% of patients are at greater risk of developing late toxicities than the average patient [4], but only 5-10%, known as hypersensitive, will actually develop late complications [5, 6].
Identifying these patients at risk of side effects before the start of treatment is key to optimize the treatment of all patients.
HYPERSENSITIVE PATIENTS WHO WILL DEVELOP LATE TOXICITIES
5-10% OF PATIENTS
Standard doses may be too high [7,8]
PATIENTS WHO WILL NOT DEVELOP LATE TOXICITIES
90-95% OF PATIENTS
Standard doses may be below their tolerance level [7,8]
The efficacy of radiotherapy depends largely on the dose delivered to the tumor. The higher the dose, the greater the likelihood of tumor control and cure.
However, the higher the dose, the greater the side-effects, so the dose must not exceed the patient’s tolerance threshold, otherwise significant side-effects may occur.
TOWARDS PERSONALIZED RADIOTHERAPY
A major challenge in clinical radiobiology is therefore to predict the individual radiosensitivity of patients, in order to propose a tailor-made treatment, adapted to each patient.
This is precisely the aim of the tests developed by NovaGray.
SCIENTIFIC REFERENCES AND PUBLICATIONS
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.