Introduction: Breast scintigraphy (BS) with the bone-seeking agent 99mTc-medronate (MDP) can be usefully combined with mammography to diagnose and characterize questionable breast lumps. However this radiotracer does not seem to provide any further prognostic information about breast cancer. Therefore we investigated the prognostic yield of MDP-BS searching for correlations between scintigraphic findings and the major biological and histologic parameters.
Materials and methods: We retrospectively analyzed a series of 44 primary breast cancers. All patients had undergone 99mTc-MDP bone scan for preoperative staging, as well as conventional breast imaging. We statistically compared the cancer/background ratio (c/b index) with lesion histotype, diameter, grading, and the tissue concentrations of steroid receptors, cathepsine D, type 1 timidine kinase, pS2 and p53 proteins.
Results: MDP-BS failed to depict 11 of 44 lesions (O 0.5-2 cm), detected 7 of 16 mammographically questionable lesions and correctly visualized the two multifocal cases. Also, MDP-BS depicted no metastatic axillary lymph nodes. We found no statistically significant correlation between the c/b index and the prognostic markers.
Discussion and conclusions: Differently from BS with 99mTc-MIBI, 201T1, 18F-FDG, 111In-OCT and radiolabeled estrogens and despite its good overall accuracy, MDP-BS appears to have no prognostic role. In fact, despite the well-known capability of soft tissue lesions to take up the tracer, MDP tumor trapping seems to depend mainly on the increased permeability of neovessels and on interstitial space enlargement. Few reports are available in the literature on the correlation between in vivo MDP uptake by the breast cancer and prognostic parameters. Thus, we tested possible correlations between the amount of MDP taken up by the breast cancer, histologic features and cell concentrations of some major biomarkers. The lack of any statistical significance is in agreement with the theory, and confirms the little prognostic value of MDP-BS. Nevertheless, further trials are warranted on larger series of cases to validate our personal findings.