The use of PET/CT in the management of breast cancer – the Royal Marsden Hospital experience.
Authors: Constantinidou A , Martin A , Sharma B , Johnston S 
Published: December 2010

Abstract #4027

Background&#x2028; Despite the increasing use of Positron Emission Tomography/Computed Tomography (PET/CT) in the management of patients with breast cancer, its role is yet to be defined. The aim of this large retrospective single-institution study was to identify the areas where this imaging tool has been beneficial (either as a single modality or in comparison with conventional imaging) and to assess its contribution in optimising management.&#x2028; Materials and Methods&#x2028; We reviewed PET/CT scans performed on breast cancer patients as part of their management in our institution. We determined the indication for the scan, the result, concordance/discordance with other imaging modalities and whether the use of PET/CT had altered patient management.&#x2028; Results&#x2028; One hundred and eighty two (182) PET/CT scans performed in 96 patients between July 2004 to June 2008 and the corresponding case notes were reviewed. The indications for performing the scan were: Staging (S) = 71, Response Assessment (RA) = 64, Clarification (C) of findings on other imaging = 25 and Reassurance (ASS) in 22 of the cases.&#x2028; In the S group 52 PET/CT scans demonstrated FDG avid disease, 14 were negative whereas 5 scans showed low-grade FDG uptake. Positive scans were helpful in accurately defining the extent of the disease and guided further localized or systemic treatment. PET/CT was particularly useful for detecting occult lytic bone metastases.&#x2028; In RA, PET showed Complete Response in 3 cases, Partial Response in 33 cases, Stable Disease in 10, Progressive Disease in 15 and Mixed Response in 3. Early RA (after 2 cycles) was allowed because of the advantage of PET/CT to assess changes in metabolic activity that precede anatomical changes. PET/CT was particularly useful for bone response assessment.&#x2028; PET/CT was used for the clarification of indeterminate lesions on CT (n=9), MRI (n=7), isotope bone scan (n=5), CXR (n=1) or combination of these modalities (n=3). It was negative in 17 cases. Disease was confirmed in 7 cases and in 2 of these cases the burden of metastatic disease was found to be significantly less on PET compared to the other modalities. In 1 case PET/CT failed to characterize indeterminate lesions.&#x2028; In the ASS group all PET/CT scans were negative.&#x2028; The management of 14 patients was substantially altered. In some cases appropriate local treatment (surgery, radiotherapy) was administered where PET/CT showed absence of metastatic disease, conversely systemic treatment was given when PET/CT demonstrated metastatic disease (hitherto occult or indeterminate on other workup).&#x2028; Discussion&#x2028; In breast cancer PET/CT is useful in accurately staging metastatic disease not only by revealing unsuspected metastasis but also by clarifying false positive findings shown on conventional imaging. It is effective in assessing response to chemotherapy and hormonal treatment earlier than any other method currently available. Its role is essential in clarifying equivocation on other imaging modalities. Incorporation of PET/CT in these areas of breast cancer management contributes to treatment optimisation. Formal guidelines for the use of this modality in breast cancer are warranted.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 4027.