Depuis les années 1990, plusieurs travaux ont mis en évidence des troubles cognitifs chez les patientes traitées pour un cancer du sein par chimiothérapie, mais aussi par hormonothérapie. Malgré ce fréquent constat, la nature exacte de ces troubles et les mécanismes impliqués ne sont toujours pas élucidés. Après avoir fait le point sur l’impact des différentes thérapies anticancéreuses sur les fonctions cognitives dans le cancer du sein, nous évoquerons de nouvelles perspectives pour la recherche dans ce domaine. De plus, du fait de la survenue chez certaines patientes de troubles cognitifs avant même le début du traitement par chimiothérapie, nous évoquerons l’hypothèse d’un impact des bouleversements psychosociologiques après le diagnostic du cancer sur le fonctionnement cognitif. Nous soulignerons également l’importance des études chez les patientes âgées, puisque l’âge n’est pas un critère limitant la prescription des traitements. Enfin, nous évoquerons le développement récent des études en imagerie cérébrale qui visent à préciser les substrats neuraux de ces modifications cognitives.
The impact of cancer and its treatment on cognitive function: the example of breast cancerCognitive impairments in cancer represent a new field of interest that is directly linked to complaints reported by cancer survivors. Because of the increase in the treatments now available, including chemotherapy, radiotherapy, hormone-based therapy and, more recently, targeted therapies, mild but handicapping cognitive dysfunctions are frequently reported and can concern long periods of post-treatment. Although these deficits are reported in different cancer populations, the great majority of studies has been conducted in breast cancer after adjuvant chemotherapy. But the nature and mechanisms underlying these deficits are still poorly understood. This paper intends to review cognitive impairment after treatments for breast cancer. Studies on this topic generally report that chemotherapy induces memory loss, processing speed and attention and executive functions problems. Afterwards, we will show that other factors, little investigated for the moment, are also likely to cause cognitive dysfunctions: recent longitudinal studies, with a base measurement point before chemotherapy, demonstrated evidence of cognitive impairment prior to chemotherapy, suggesting that several parameters, including psychopathological and psychosocial factors (depression, anxiety, self disturbances) or biological factors (cytokine level), have clearly to be taken into account. Then, we will focus on studies investigating the situation in elderly cancer populations as these patients are highly likely to be confronted with cognitive deficits and with cancer, and the administration of chemotherapy treatment doesn’t really take into account the age of the patients. Finally, recent neuroimaging studies began to better understand the neurobiological mechanisms underlying cognitive impairment in breast cancer. The patients demonstrated larger patterns of activation from control subjects, sometimes in spite of normal cognitive scores, suggesting mechanisms of compensation. Future studies should be developed and adopt a sensitive method with longitudinal design and the latest imaging techniques to explain cognitive impairment in cancer.
