¹⁸FDG uptake and total lesion glycolysis measured at baseline and after 2 courses of neoadjuvant chemotherapy are powerful tools to predict relapse in patients with ER+/HER2- breast cancer

Objectives This study investigated whether ¹⁸FDG-PET/CT performed at baseline and during neoadjuvant chemotherapy (NAC) is able to early depict estrogen receptor-positive/human epidermal growth factor receptor 2-negative (ER+/HER2-) breast cancer patients with poor clinical outcome.

Methods NAC regimen consisted in 4 cycles of epirubicin plus cyclophosphamide, followed by 4 courses of docetaxel. The patients had ¹⁸FDG-PET/CT at baseline and after two cycles. After completion of NAC, all patients had breast surgery with axillary lymph nodes dissection. We assessed the impact of two PET parameters, “maximum” standardized uptake values (SUV_max) and total lesion glycolysis (TLG), on event-free survival.

Results 98 consecutive patients with ER+/HER2- breast cancer were included. ¹⁸FDG-PET/CT revealed distant metastases in 14 patients (14%). Overall survival was significantly shorter in these patients than in the 84 patients classified M0 at baseline ¹⁸FDG-PET/CT (P < 0.001). In M0-patients, high SUV_max at baseline was associated with shorter EFS (P < 0.001). Twelve patients had tumor SUV_max >10 and a 3-year EFS of 49% (vs 92% in patients with baseline SUV_max ≤ 10). A low change in SUV_max between PET₁ and PET₂ was also associated with recurrence (P = 0.033), as was a low change in TLG (P < 0.001). Contrarily to PET-based prediction, the extent of pathological response after completion of NAC (partial/complete vs non-responders) was poorly correlated to the risk of relapse.

Conclusions Baseline tumor ¹⁸FDG uptake and modifications after 2 cycles of neoadjuvant chemotherapy are prognostic of outcome in patients with ER+/HER2- breast cancer.