Combined PET–CT and axillary lymph node marking with radioactive iodine seeds (MARI procedure) for tailored axillary treatment in node-positive breast cancer after neoadjuvant therapy
Menée auprès de 93 patientes atteintes d'un cancer du sein avec envahissement ganglionnaire (âge médian : 49 ans), cette étude évalue l'intérêt, du point de vue du taux de curages ganglionnaires évités, d'une procédure comportant avant une chimiothérapie néo-adjuvante une tomographie numérique par émission de positrons à base de fluorodésoxyglucose 18F pour stadifier la maladie, puis un marquage des métastases ganglionnaires axillaires par l'iode 125 pour identifier les ganglions à réséquer durant le traitement chirurgical
Background : The treatment of axillary lymph node metastases after neoadjuvant systemic therapy (NST) remains debatable and axillary lymph node dissection (ALND) is still the standard of care. Marking axillary lymph nodes with radioactive iodine seeds (MARI procedure) is accurate in restaging the axilla after NST (false-negative rate 7 per cent). Here, the potential of tailored axillary treatment, determined by combining the results of PET–CT before NST with those of the MARI procedure after NST, was analysed. Methods : A cohort of axillary node-positive patients was used to construct a hypothetical treatment algorithm based on a combination of PET–CT and the MARI procedure. In the algorithm, the number of fluorodeoxyglucose (FDG)-avid axillary lymph nodes (1–3 versus 4 or more) before NST and the tumour status of the MARI node (positive versus negative) after NST were used to tailor axillary treatment. All patients in the cohort underwent ALND, allowing estimation of potential overtreatment and undertreatment. Results : A total of 93 patients were included in the study. Between one and three FDG-avid axillary lymph nodes were observed in 59 patients, and four or more in 34 patients. The MARI node was tumour-negative in 32 patients and showed residual disease in 61. Treatment according to the constructed algorithm would have resulted in 74 per cent of patients avoiding an ALND, with potential undertreatment in three patients (3 per cent) and overtreatment in 16 (17 per cent). Conclusion : Tailored axillary treatment after NST in node-positive patients, by combining PET–CT before NST and the MARI procedure after NST, has the potential for ALND to be avoided in 74 per cent of patients.