Prognostic factors in breast cancer patients evaluated by PET/CT prior to neoadjuvant chemotherapy.

Abstract

e12113 Background: Neoadjuvant chemotherapy (NAC) is an important modality in breast cancer treatment. We sought to identify pre-treatment prognostic factors in patients who had positron emission tomography paired with diagnostic quality contrast-enhanced CT (PET/CT) prior to neoadjuvant chemotherapy with respect to pathologic complete response (pCR) , survival and relapse-free survival (RFS). Methods: We retrospectively analyzed 118 breast cancer patients who had pre-treatment PET/CT imaging and received NAC from 2008-2014. We collected data on molecular markers, PET/CT, pCR, survival, and disease status. Results: The median follow up was 44 months(range 7.3-101.5),median age was 51 years; 47% were stage II, 53% stage III. 52% of patients had hormone receptor (HR) positive/HER2 negative disease, 31% of tumors were HER2 positive, and 17% of tumors were triple-negative. 92.5% with HER2 positive tumors received NAC containing at least one HER2 targeted agent. Pre-treatment standard uptake value (SUV) max of the primary breast tumor showed no statistically significant relationship to survival, RFS, or pCR. PET avid (>2 SUV) extra-axillary nodes such as internal mammary and supraclavicular was associated with a non-statistically significant trend towards reduced RFS (p=0.06, HR=0.13-1.06). pCR overall was 37.5% for HER2 positive tumors, 15% in triple-negative tumors, and 8% in HR positive/HER2 negative tumors. Log-rank analysis with post-hoc pairwise comparisons showed a significant difference between the RFS of triple-negative tumors and HER2 positive tumors (p=0.001), while comparison between HR positive/HER2 negative and HER2 positive was not statistically significant (p=0.11). Multivariate cox regression analysis, which included grade and stage of tumors, showed HER2 positivity to be associated with a favorable outcome (p=0.04, HR=0.22 (0.05-0.94)). Conclusions: Within this cohort, pre-treatment SUV max of the primary tumor showed no prognostic value with regard pCR or RFS. PET avid extra-axillary metastasis trended towards reduced RFS. Patients with HER2 positive tumors had the highest pCR and RFS comparable to classically favorable subgroups such as HR positive/HER 2 negative.