¹⁸F-FDG PET imaging of breast cancer: evaluation of the metabolic behaviour of the different breast cancer subtypes and prediction of the tumor response to neoadjuvant chemotherapy

Positron Emission Tomography (PET) with ¹⁸Fluoro-deoxyglucose (¹⁸F-FDG) is the reference imaging examination for in-vivo quantification of the glucidic metabolism of tumour cells. It allows for the monitoring of tumour metabolic changes during chemotherapy. Breast cancer comprises several distinct genomic entities with different biological characteristics and clinical behaviours, leading to different tailored treatments. The aim of this doctoral thesis was to evaluate the relationship between the different biological entities of breast cancer and the tumour metabolic behaviour during neoadjuvant chemotherapy. We have also retrieved, among the various metabolic parameters on PET images, the most reliable ones to predict, as early as after the first neoadjuvant cycle, the final tumour histologic response and patient's outcome. We have also evaluated early changes in tumour blood flow, using a tumour first-pass model derived from a dynamic ¹⁸F-FDG-PET acquisition. The first article presented in this thesis has underlined the strong correlation between breast cancer subtypes, and the tumour metabolic behaviour during chemotherapy. The following three articles have demonstrated that tumour metabolic changes after the first neoadjuvant cycle can predict the final histologic complete response at the end of the treatment, both in triple-negative and HER2 positive tumours. Concerning the luminal/HER2 subtype, the early metabolic response mainly predicts patient's outcome. These results should lead, in the near future, to PET-guided neoadjuvant strategies, in order to adapt the neoadjuvant treatment in poor-responding women. Such a strategy should lead to enhanced personalized medicine. (author)