18F-FDG PET/CT is regarded as one of the essential imaging for establish the efficacy of breast cancer therapy and the measures of tumor burden showed promises to predict OS in patients with mBC. Everolimus leads to decreased protein synthesis, cell metabolism and cell proliferation in solid tumors. Identification of predictive markers for everolimus-based treatment remains a major issue, but to date, no predictive markers have been established. The aim of this study is to evaluate an optimal ΔSUV% [(SUV baseline-SUV 3 months)/SUV baseline] as a predictive factor of OR and DFS in patients with mBC cancer receiving everolimus and exemestane in 1^ line treatment.
The study included 31 patients with a new diagnosed luminal B phenotype mBCs treated with everolimus and exemestane in ASST of Cremona and INT of Milano between May 2013 and March 2018. The 18F-FDG PET/CT and glycemia were performed at baseline and after three months of treatment. Patients who stopped treatment before 10 months were considered as in a progressive disease (PD), otherwise a duration of therapy > 10 months was scored as no PD. ROC analysis was performed to determine the optimal cut-off value of ΔSUV% to differentiate PD from non-PD women using Youden Index. Time to progression survival (TTP) was estimated by Kaplan-Mayer method. Spearman’s rank correlation coefficient (rho) was calculated to describe correlation between ΔSUV% and Δglycemia.
An optimal cut-off ΔSUV% value of 29% was proposed for discriminate patients with PD from those without PD: patients with ΔSUV%<29% had a median TTP of 3.11 months versus 9.29 months for patients with ΔSUV%>29% (p = 0.0036) and more frequently had PD within 10 months: 100% vs 53%, respectively (p = 0.005). There was a negative correlation between ΔSUV% and Δglycemia (rho=-0.32, p = 0.15).
Our results showed that ΔSUV> 30% tested with 18F-FDG PET/CT after 3 months of treatment identified patients who had benefit from the everolimus-exemestane combination in term of response and TTP (>10 months). Moreover we have observed an inverse correlation between ΔSUV and Δglycemia. These results warrant further validation with a potential integration with molecular biomarkers related to tumor metabolism and mTOR signalling.
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Breast Cancer Unit and Translational Research Unit, Azienda Socio-Sanitaria Territoriale Cremona, Italy.
Has not received any funding.
The author has declared no conflicts of interest.