6FDG PET scan evaluation of suspicious breast lesions developing after breast conservation therapy for breast cancer

Abstract

612 Background: Breast Conservation Therapy (BCT) for early breast cancer is an effective option in selected patients with primary breast cancer. Mammographic evaluation of breast abnormalities developing after BCT can be difficult. Positron Emission Tomography (PET) is a valuable imaging tool in oncology. We investigated the efficacy of PET imaging in predicting the nature of suspicious breast changes following BCT. Methods: All patients with prior BCT with suspicious mammographic or breast examination findings necessitating biopsy evaluation were offered participation. After signed informed consent, PET imaging was performed using F-18 FDG General Electric PET scanner. Breast biopsy was obtained following the PET scan. Pathologic findings were correlated with the PET findings. Results: 33 patients were enrolled in the study between 6/1997 and 11/2003 with 31 patients completing both PET imaging and breast biopsy. The population characteristics at the time of the original breast cancer diagnosis were as follows: (1) Race and age: African Americans 21 (68%) (mean age = 46.8), Caucasian 10(32%) (mean age = 52.8). (2) Tumor size: 7 tumors ≤ 10mm, 11 between 11–20mm, 11 between 21–30mm, and 2 between 31–50mm. (3) Nodal Status: 21(68%) node negative, 10(32%) node positive. (4) Hormone receptor status: 51% negative, 49% positive.Biopsy/PET Results: 58% of the surgical biopsies were negative while 42% were positive (recurrent disease). 58% of PET scans were negative while 42% were positive. There was 1 false negative PET scans and 1 false positive scan. Overall the sensitivity of PET was 92.31%;while specificity was 94.44%. Positive predictive value of PET was 92.31%. PET scan was highly consistent with biopsy results (Kappa Co-efficient k=0.92). The single patient with a negative biopsy following a positive PET scan was found to have wide spread metastatic disease. The single patient with negative PET, but positive disease by biopsy had DCIS. Conclusions: PET imaging appears to be a reliable radiographic approach for the initial evaluation of suspicious breast lesions developing after BCT. No significant financial relationships to disclose.