Prognostic impact of 18F-FDG PET/CT staging and of pathological response to neoadjuvant chemotherapy in triple-negative breast cancer.

PURPOSE: Mortality is high in patients with locally advanced triple-negative breast cancer (TNBC), especially in those with residual tumour after neoadjuvant chemotherapy (NAC). The aim of this study was to determine if pretreatment (18)F-FDG PET/CT staging and pathological findings after NAC could together allow stratification of patients into prognostic groups. METHODS: Initial staging with (18)F-FDG PET/CT was performed prospectively in 85 consecutive patients with stage II/III TNBC. Correlations between PET findings and disease-specific survival (DSS) were examined. In patients without distant metastases on PET staging, the impact of pathological response to NAC on DSS was examined. Patterns of recurrence were also analysed. RESULTS: (18)F-DG PET/CT revealed distant metastases in 11 of 85 patients (12.9 %). Among 74 M0 patients, 23 (31.1 %) showed a pathological complete response (pCR) at surgery, while 51 had residual invasive disease (no pCR). DSS differed considerably among the three groups of patients (log-rank P < .001): among patients with occult metastases on baseline PET/CT, 2-year DSS was 18.2 %, and among patients without initial metastases on PET/CT, 5-year DSS was 61.3 % in patients without pCR after NAC and 95.2 % in those with pCR. Of the 51 patients who did not achieve pCR, 21 relapsed (17 developed distant metastases). The sites of distant recurrence were: lung/pleura (nine patients), brain (eight patients), liver (six patients), distant lymph nodes (six patients) and bone (five patients). CONCLUSION: In patients with clinical stage II/III TNBC, (18)F-FDG PET/CT findings at initial staging and pathological response at the end of NAC allow three groups of patients with quite different prognoses to be defined. Extraskeletal recurrences predominated. Specific follow-up strategies in patients with TNBC who do not achieve pCR deserve investigation.