Abstract P3-11-11: Dedicated breast PET (dbPET) a unique functional new tool to accurate quantify response to neoadjuvant therapy in breast cancer
Authors: Herranz Michel , Dominguez Ines , Ruibal Alvaro , Brozos Elena , Teo Sze Yiun , Rodriguez Carmela , Chaal Jasper , Curiel Maria Teresa , Cueva Juan , Fernandez Beatriz , Pavón Gabriel G , Fortier Marielle , Lopez Rafael 
Published: May 2015

Background: Breast cancer is one of the most common cancers in women. Approximately 232,670 new cases of breast cancer (14% of all new cancer cases) and 40,000 breast cancer deaths (6,8% of all cancer deaths) are expected to occur among US women in 2014. Since 1990, breast cancer death rates have dropped by 34%. Continued progress in the control of breast cancer will require sustained and increased efforts to provide high-quality screening, diagnosis, and treatment Recently, the MAMmography with Molecular Imaging (MAMMI) dedicated breast PET (dbPET) has emerged as an additional imaging tool for breast cancer diagnosis, clarification of complex lesions and therapy follow-up. This study is aimed to determine whether correlations exist between physiological images with 18FDG of pre, post-2-cycles and post Neoadjuvant Chemotherapy, with a predictive value of response.

Methods: Twenty-five patients, and three scan points: pre, 2 cycle and post Neoadjuvant Chemotherapy were included in this analysis A prone position high-resolution dedicated breast PET (MAMMI-dbPET) was performed 60 min after administration of 90-120 MBq of 18F-FDG. Maximum standardized uptake value (SUVmax) quantification, volume characterization, positioning in all three space-axes, distances to reference points (proximal breast limit, nipple areola complex) were registered.

Results: When treatment was successful, a significant difference was found between pre and post neoadyuvant chemotherapy status and the SUVmax (p &lt; 0.001) of breast tumors. Pre Neoadjuvant (mean SUVmax, 11.4) demonstrated a significantly higher SUVmax than did post 2 cycles tumors (median SUV, 4.7) (p= 0.025). No statistical significant difference was found for SUVmax of post-2 cycles vs. post lesions with a mean SUVmax of 4.7 and 3.9 (p=0.25) respectively. A statistically significant difference was found for volume measurement of pre vs. post-2 cycles vs post Neoadjuvant therapy lesions. A clear qualitative difference by three different observers has been reported among dbPET and MRI volume characterization. A 21% of volume (measurement) discrepancies was found, always with a volume over-estimation by magnetic resonance (structural vs functional imaging). An exquisite -and unexpected- millimetric correlation with post-surgical pathology at the end of neoadjuvant theraphy has been found in dbPET images.

Conclusions: dbPET MAMMI has proven to be an excellent tool for quantification, 3D spatial localization and monitoring of neoadjuvant therapy, showing, thanks to its functional nature, earlier and better precision and accuracy than conventional techniques (MRI). Post 2-cycle and Post Neodayuvant Chemotherapy breast cancer tumors consistently display lower 18FDG uptake than pre treatment tumors when treatment is successful. This data suggest that SUVmax measurements of 18FDG-dedicated breast PET can provide valuable information about therapy efficiency. Such an association might be of relevant importance to treatment continuity or adjustement.

Citation Format: Michel Herranz, Ines Dominguez, Alvaro Ruibal, Elena Brozos, Sze Yiun Teo, Carmela Rodriguez, Jasper Chaal, Maria Teresa Curiel, Juan Cueva, Beatriz Fernandez, Gabriel G Pavón, Marielle Fortier, Rafael Lopez. Dedicated breast PET (dbPET) a unique functional new tool to accurate quantify response to neoadjuvant therapy in breast cancer [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-11-11.