Molecular signatures provide more precise information on the prognosis and efficacy of treatments in breast cancer. In particular, they make it possible to avoid the often useless recourse to chemotherapy. The explanations of Professor Gilles Freyer.
In the treatment of breast cancer, chemotherapy does not always bring significant results. Hence the importance of being able to assess the relevance of using these treatments, which are sometimes unnecessarily used in this disease when their toxic side effects are known. For this, doctors need to know two elements, prognostic on the evolution of the disease, or predictive on the usefulness of such or such treatment.
Today, this evaluation is aided by molecular – or genomic – signatures which, by identifying the genes that are expressed in a patient’s tumour, make it possible to say whether or not it is appropriate to prescribe chemotherapy. This analysis of the genes of the tumor makes it possible to show whether or not there is a good response to this treatment.
“Knowing which patients need chemotherapy”
“The challenge is to know which patients need chemotherapy because they have a worse prognosis but who need it above all because this chemotherapy will be effective for them”, explains Gilles Freyer, head of the oncology department. at the Hospices Civils de Lyon.
Until then, the choice was made on the basis of statistical studies which gave, according to clinical characteristics, a prediction of the risk of death at 5, 10 or 15 years and indicated the benefit of treatment with chemotherapy or hormone therapy. “It is a good approach to the prognostic and predictive question, but it is an approach for a population: for a given patient, we do not know the precise prognosis or the effectiveness of chemotherapy in her particular case”, underlines Gilles Fraier.
“An individualization of risk assessment”
“Molecular signatures put in place a genomic approach which allows an individualization of the risk assessment in relation to a patient and the nature of her tumor”, continues the oncologist who specifies the advantages and limits of the different signatures available. today: “One is moderately prognostic but very predictive of the benefit of chemotherapy, others are very good prognostic signatures without being predictive and others, of more limited use, predict the benefit of chemotherapy very well. prolonged hormone therapy.
But, insists Gille Freyer, these molecular signatures should not be interpreted “to the letter”: “We must refine the prediction according to histo-pathological data”.
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