Knowledge of the factors influencing uptake is important when interpreting FDG PET/CT scans. Also, findings that FDG uptake is highest in those patients with poor prognostic features (high grade, hormone receptor negativity, triple negativity, metaplastic tumours) is helpful to determine who are the best candidates for baseline staging.

BackgroundThis study prospectively evaluated the yield of fluorodeoxyglucose positron emission tomography/computed tomography (18FDG-PET-CT) in patients with clinical stages II and III breast cancer and the impact of PET-CT results on prognosis.MethodsIn the course of 71 months, 254 consecutive patients with clinical stages II and III breast cancer (based on clinical examination, mammography, breast magnetic resonance imaging, and locoregional ultrasonography) underwent 18FDG-PET-CT. The yield was assessed in the whole population and for each American Joint Committee on Cancer subgroup. The prognostic impact of PET-CT findings was analyzed. Tests of statistical significance were two-sided.Results 18FDG-PET-CT changed the clinical stage in 77 of 254 patients (30.3%; 95% confidence interval [CI] = 25.0% to 36.2%). It showed unsuspected N3 disease (infraclavicular, supraclavicular, or internal mammary nodes) in 40 patients and distant metastases in 53. PET-CT revealed distant metastases in 2.3% (1 of 44) of clinical stage IIA, 10.7% (6 of 56) of stage IIB, 17.5% (11 of 63) of stage IIIA, 36.5% (27 of 74) of stage IIIB, and 47.1% (8 of 17) of stage IIIC patients. Among 189 patients with clinical stage IIB or higher disease and adequate follow-up, disease-specific survival was statistically significantly shorter in the 47 patients scored M1 on 18FDG-PET-CT in comparison with those scored M0, with a three-year disease-specific survival of 57% vs 88% (P < .001). In multivariable analysis, only distant disease on PET-CT and triple-negative phenotype were statistically significant prognostic factors. The relative risk of death was 26.60 (95% CI = 6.60 to 102.62) for M1 vs M0 patients.ConclusionsThe yield of 18FDG-PET-CT appeared substantial in patients with clinical stage IIB or higher breast cancer. In these patients, 18FDG-PET-CT provided powerful prognostic stratification.

Purpose: High levels of tumor-infiltrating lymphocytes (TIL) before neoadjuvant chemotherapy (NAC) are associated with higher pathologic complete response (pCR) rates and better survival in triple-negative breast cancer (TNBC) and HER2-positive breast cancer. We investigated the value of TIL levels by evaluating lymphocyte infiltration before and after NAC.Experimental Design: We assessed stromal TIL levels in 716 pre-and posttreatment matched paired specimens, according to the guidelines of the International TIL Working Group.Results: Pre-NAC TIL levels were higher in tumors for which pCR was achieved than in cases with residual disease (33.9% vs. 20.3%, P ¼ 0.001). This was observed in luminal tumors and TNBCs, but not in HER2-positive breast cancers (P Interaction ¼ 0.001). The association between pre-NAC TIL levels and pCR was nonlinear in TNBCs (P ¼ 0.005). Mean TIL levels decreased after chemotherapy completion (pre-NAC TILs: 24.1% vs. post-NAC TILs: 13.0%, P < 0.001). This decrease was strongly associated with high pCR rates, and the variation of TIL levels was strongly inversely correlated with pre-NAC TIL levels (r ¼ À0.80, P < 0.001). Pre-NAC TILs and disease-free survival (DFS) were associated in a nonlinear manner (P < 0.001). High post-NAC TIL levels were associated with aggressive tumor characteristics and with impaired DFS in HER2-positive breast cancers (HR, 1.04; confidence interval, 1.02-1.06; P ¼ 0.001), but not in luminal tumors or TNBCs (P Interaction ¼ 0.04).Conclusions: The associations of pre-and post-NAC TIL levels with response to treatment and DFS differ between breast cancer subtypes. The characterization of immune subpopulations may improve our understanding of the complex interactions between pre-or post-NAC setting, breast cancer subtype, response to treatment, and prognosis.