Molecular subtyping of breast cancer using dedicated breast PET-CT.

Abstract

e22090 Background: Recently dedicated breast 18FDG breast PET-CT has emerged as an additional imaging tool for assessment and staging of primary breast cancer. Expression of specific molecular markers such as estrogen receptor (ER), progesterone receptor (PR), and HER2 status, has direct prognostic and therapeutic implications in patient management. This study aimed to determine whether correlations exist between 18FDG up-take of the primary breast cancer lesions and these predictive and prognostic factors. Methods: Before undergoing surgery 114 patients with primary breast cancer underwent 18FDG breast PET-CT. The maximum standardized uptake value (SUVmax) of the primary breast cancer was measured in each patient and standard immunohistochemistry was performed on a surgical specimen to characterize the receptor state of tumor cells. Appropriate statistical tests were used to test for any association that may exist among ER, PR, and HER2. Results: A significant association was found between a triple negative status and the SUVmax (p < 0.001) of breast tumors. ER-negative tumors (mean SUVmax, 10.4) demonstrated a significantly higher SUVmax than did ER-positive tumors (median SUV, 5.1) (p= 0.045). No statistical significant difference was found for SUVmax of PR-negative vs. PR-positive lesions with a mean SUVmax of 8.6 and 4.9 (p=0.15) respectively. No statistical significant difference was found for SUVmax of HER2-negative vs. HER2-positive lesions with mean SUVmax of 6.4 and 5.3 respectively (p=0.55). If either ER or PR was positive, then the other tended to be positive as well (chi2 = 84%, P < 0.01). No such significant relationship was detected between PR or ER and HER2 (P > 0.05). Conclusions: ER-negative breast cancer tumors display higher 18FDG uptake than ER-positive tumors. Triple-negative breast tumors are associated with increased 18FDG uptake commensurate with their aggressive biology. The data suggest that SUVmax measurements of 18FDG breast PET-CT can provide valuable information about the state of ER, PR, and HER2 and the associated glucose metabolism of the primary breast cancer lesions. Such an association may be of importance to treatment planning and outcome in these patients.