P2-09-10: Giant or Windmill? 18F-FDG-PET/CT Semi-Quantitative Parameters and Biological Prognostic Parameters in Women with Breast Cancer Treated with Neoadjuvant Chemotherapy: A Multicentric Study in La Mancha.

Abstract

Background: To analyze the possible predictive-prognostic value of 18F-FDG-PET/CT to evaluate response to primary preoperative neoadjuvant (NA) chemotherapy (CT) in women with breast cancer (BC) a multicenter study is being conducted in most Hospitals in Castilla - La Mancha (central Spain). As per protocol a PET/CT study has to be conducted prior to 1st cycle, after 2nd cycle and at the end of induction CT. We report here the initial results with the correlation between the PET/CT results and pathological-radiological-clinical findings prior to NA CT. Aim: To analyze the correlation between 18F-FDG uptake assessed by PET/CT and histopathological and inmunohistochemical prognostic factors in BC prior to NA CT. Material and methods: 68 women diagnosed of BC (36 with locally advanced BC) were prospectively evaluated. PET/CT was requested in the initial staging previous to NA CT. Clinical and metabolic stages were assessed according to TNM classification. All biological prognostic parameters, such as ER, PR, p53 and c-erbB-2 expression, proliferation rate (Ki-67), and grading (SBR) were determined from tissue of the primary tumour prior to NA CT. All patients underwent an 18F-FDG PET/CT with a dual-time-point acquisition performed in the early phase 1 h after FDG administration (PET-1) and in the delayed phase 3 h after FDG administration (PET-2). Both examinations were evaluated qualitatively and semiquantitatively with calculation of SUVmax values in PET-1 (SUV-1) and in PET-2 (SUV-2) and the percentage variation of the standard uptake values (retention index) between PET-1 and PET-2. Metabolic, clinical and biological parameters were correlated. Student, ANOVA and Bonferroni tests were used to compare the means, chi-score to compare proportions and Pearson correlation to compare two quantitative variables. Results: A positive relationship was found between the SUVmax, tumour size, clinical and metabolic stages. SUV-1 and SUV-2 values showed significant statistical correlation (p<0.05) with PET stage and tumour size assessed by PET. On the contrary, the retention index showed relation with clinical stage (p<0.05). About the biological parameters, retention index showed the best results with positive and significant relation (p<0.05) with histological grade, ER status, Ki-67 and c-erbB-2 expression. Isolated SUV values only showed significant relation to Ki-67 expression. Conclusion: The retention index showed the best correlation with biological and clinical parameters compared to isolated SUVmax values. It may be useful as a predictive marker of tumor biological behavior. Nevertheless these are only the results of PET/CT prior to NA CT, with longer follow up we hopefully will be able to look at the correlation between PET/CT and radiological, clinical and pathological response after NA CT. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-09-10.