Abstract P1-02-12: High-resolution specimen-positron emission mammography (s-PEM) indicates the spread of cancer in breast-conserving surgery

Abstract

Abstract Background: Breast cancer surgery, including breast-conserving surgery or sentinel lymphnode biopsy, has become minimally invasive. Recent consensus guidelines on the margins for breast-conserving surgery have defined a negative margin as one with no ink on tumor, regardless of the distance from the tumor, whereas a positive margin has ink on the tumor. Therefore, the extent of required tumor resection will decrease for cosmoses and expand the indications for breast-conserving surgery. Therefore, there is a real need for a more accurate imaging of tumor spread. In particular, a functional imaging of breast cancer specimens will help determine negative margins in breast-conserving surgery. We collaborated with Sendai Medical Imaging Center (SMIC) who have high-resolution positron emission mammography (PEM) with the novel scintillator Pr3+-doped transparent ceramic Lu3Al5O12 (Pr:LuAG) for the imaging of breast cancer specimen with 18F-fluodeoxyglucose (FDG). Methods: With the approval of the hospital ethics committee, positron emission tomography (PET) was conducted preoperatively on the day of surgery with 18F-FDG. After the PET results were explained to the patients, breast-conserving surgery was performed in 11 patients from February to July 2014. In the operating room, medical staff exposures were calculated with a portable dosimeter. All of the cases were carried out intraoperative frozen sections that were taken from all sides of the outside of the specimens. The specimens were serially sectioned in 5-mm slices for permanent histology. After the specimens were removed, they were sent to the SMIC and high-resolution specimen-PEM (s-PEM) was conducted. We evaluated the detection rate of s-PEM in in situ or invasive lesions (extent of locations were tolerated up to a 10% error), the predictive value of margin status between s-PEM and frozen section analysis and medical stuff exposure. Results: In 11 breast specimens, eight invasive lesions and 15 in situ lesions (excluding the foci that exist in less than three carcinoma ducts) were confirmed by permanent histology. s-PEM detected all of the invasive lesions and 14 out of 15 in situ lesions. Three breast specimens had positive margins in permanent histology. Two out of three cases with positive margin accumulated 18F-FDG at the edge of the specimens, which were considered positive margins with s-PEM, whereas positive margins were only one out of three of the frozen section analysis. In contrast, a false positive margin was found in only one case with s-PEM, which confirmed the preoperative core-needle biopsy that was diagnosed as an intraductal proliferative lesion. Medical staff exposure was determined for the operator, first assistant, second assistant, anesthesiologist, scrab nurse and circulating nurse as 31, 34, 25, 11, 21 and 6 µSV, respectively. Conclusion: s-PEM detected not only invasive lesions but also in situ lesions with great accuracy. It might accelerate the decrease in the extent of resection required in breast-conserving surgery. However, further studies are needed to elucidate the characteristics of the false positive cases in s-PEM. Citation Format: Gou Watanabe, Masatoshi Itoh, Dan Kyokutou, Mika Watanabe, Takanori Ishida, Akihiko Suzuki, Minoru Miyashita, Hiroshi Tada, Naoko Mori, Noriaki Ohuchi. High-resolution specimen-positron emission mammography (s-PEM) indicates the spread of cancer in breast-conserving surgery [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 P1-02-12.