Molecular profiling of metastatic breast cancer in body cavity fluids.

Abstract

61 Background: The diagnosis of malignant effusion signifies disease progression and is associated with a worse prognosis regardless of tumor origin. The cancer cells in fluids have unique genotypic and phenotypic characteristics that are uniquely different from the primary tumor. Therapeutic guidance should be based on the evaluation of tumor cells in effusions. This study reports the feasibility of molecular profiling for breast cancer metastasis in pleural and peritoneal fluids. Methods: A computer search was conducted to retrospectively identify malignant fluid samples or cell blocks for molecular profiling. A cell-block was either prepared or available for testing for all samples. An H&E slide was prepared from the cell- block and reviewed by a pathologist before any testing. Malignant cell percentages were determined for purpose of DNA microarray analysis and Sequencing. Appropriate clusters and malignant cells were marked for FISH. The results were reviewed and data compiled to calculate the yield of various molecular predictive tests. Results: We studied 172 fluid of which 28 were metastatic breast cancer (16.2%). Of the 28 breast cases, 10 IHC biomarkers could be performed in 20 (71.4 %), 1-9 in 1 (3.5 %), while 7 (25%) were insufficient. DNA microarray analysis was done in 10 (35.7%), FISH for EGFR 7 (25%), Her2 Neu FISH 11(39%), cMYC FISH 5 (17.8%) and TOPO2a by FISH 3 (10.7%). Combined IHC/FISH/MA data was available in 10, IHC and FISH data in 11 and IHC and MA data in 10 cases. Combined results of predictive markers provided information on therapeutic guidance in 21 of 28 cases. Conclusion: Molecular profiling of malignant fluids offers additional opportunities for testing those patients where other tissue samples such as needle core biopsy or resection samples are not available. Molecular profiling provides insight into the molecular characteristics of malignant cells in body cavity fluids and associated expression of unique therapeutic targets.