Positron emission tomography and breast masses: Comparison with clinical,mammographic, and pathological findings

Background: Positron emission tomography (PET) is a means of imaging tissue based upon its metabolic activity. Initial studies in the field of oncology suggest that PET may be useful for diagnosis, staging, and treatment of various tumors. Methods: Twenty-eight patients with 37 breast lesions were studied with PET using [fluorine-18] 2-deoxy-2-fluoro-D-glucose (FDG) to assess which clinico-pathological characteristics relate to FDG accumulation by the primary tumor. Results: PET-FDG was found to successfully discriminate malignant from benign breast lesions (p=0.02) and identify axillary lymph node metastases. FDG uptake by the primary tumor was found to be independent of age, menopausal status, race, tumor size, laterality, histologic differentiation, ploidy, DNA index, estrogen or progesterone receptor value, pathologic stage, and serum glucose. Higher tumor nuclear grade and S-phase were associated with more FDG accumulation by the primary tumor compared with normal breast tissue. PET-FDG correctly identified five malignant lesions that were indeter-minant for cancer both on clinical breast examination and mammography and identified one occult cancer that was neither palpable nor apparent mammographically. PET-FDG correctly identified clinical occult axillary metastatic cancer in five patients. Conclusions: This study shows that PET-FDG imaging can distinguish malignant from benign breast lesions among a diverse group of patients and suggests that PET-FDG may not only allow for preoperative staging of patients but also provide information about prognosis. This study provides impetus for continued research into PET-FDG imaging of breast lesions, which could have a major impact on the treatment of breast cancer. Presented at the 46th Annual Cancer Symposium of the Society of Surgical Oncology, Los Angeles, California, March 18–21, 1993.