FDG uptake on PET is related to biological parameters and prognosis in breast cancer. The predominance of stromal tumor-infiltrating lymphocytes (TILs) in breast cancer is a biomarker for prognosis and pathological complete response after neoadjuvant chemotherapy. However, whether whole-body PET (WBPET) and dedicated breast PET (DbPET) can reflect the amount of TILs is unclear. This study investigated the relationship between TILs and maximum standardized uptake value (SUVmax) in WBPET and ring-type DbPET.
A total of 125 invasive breast cancers underwent WBPET and ring-type DbPET and resected specimens were pathologically assessed. The impact on SUVmax on the tumor biological parameters and TILs was retrospectively evaluated. SUVmax was classified as high and low relative to the median values (WBPET-SUVmax: 2.2 and DbPET-SUVmax: 6.0).
SUVmax correlated with tumor size, nuclear grade, Ki-67 labeling index, and TILs in both WBPET and DbPET (all P < 0.001). The cut-off values of tumor size, Ki-67 labeling index, and TILs predicting high SUVmax were 20 mm, 20%, and 20%, respectively. In multivariate analysis, the predictive factors for high SUVmax were tumor size and Ki-67 labeling index for WBPET and tumor size and TILs for DbPET. A high SUVmax in DbPET was related to high numbers of TIL tumors after propensity score matching analysis; however, WBPET was not (P = 0.007 and P = 0.624, respectively).Table: 156P
Logistic regression analysis for predicting high SUVmax tumor on WBPET and DbPET
|Factors||Univariate analysis||Multivariate analysis|
|Odds ratio||P||Odds ratio||P|
|T2–3||6.18||< 0.001||13.0||< 0.001|
|Nuclear grade 3||6.48||< 0.001||2.70||0.071|
|Ki-67 labeling index ≥ 20%||3.03||0.005||3.68||0.020|
|TILs ≥ 20%||1.99||0.084||2.29||0.144|
|T2–3||4.38||< 0.001||4.81||< 0.001|
|Nuclear grade 3||4.43||< 0.001||1.82||0.238|
|Ki-67 labeling index ≥ 20%||3.54||0.001||1.39||0.513|
|TILs ≥ 20%||7.50||< 0.001||6.98||< 0.001|
Unlike WBPET, the SUVmax in ring-type DbPET can represent the immune microenvironment after adjusting for tumor biological factors. DbPET might be a biomarker of pathological response to neoadjuvant chemotherapy and prognosis.
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All authors have declared no conflicts of interest.