Assessment of residual tumour by FDG-PET: conventional imaging and clinical examination following primary chemotherapy of large and locally advanced breast cancer

Abstract

BACKGROUND: The aim of this was to evaluate FDG-PET (2-(fluorine-18)-fluoro-2-deoxy-D-glucose positron emission tomography) for assessment of residual tumour after primary chemotherapy of large and locally advanced breast cancer in comparison with conventional imaging modalities. METHODS: In a prospective multicentre trial, 99 patients underwent one or more breast imaging modalities before surgery in addition to clinical examination, namely, FDG-PET (n ¼ 89), mammography (n ¼ 47), ultrasound (n ¼ 46), and magnetic resonance imaging (MRI) (n ¼ 46). The presence of residual tumour by conventional imaging, dichotomised as positive or negative, and the level of FDG uptake (standardised uptake values, SUV) were compared with histopathology, which served as the reference standard. Patients with no residual tumour or only small microscopic foci of residual tumour were classified as having minimal residual disease and those with extensive microscopic and macroscopic residual tumour tissue were classified as having gross residual disease. RESULTS: By applying a threshold SUV of 2.0, the sensitivity of FDG-PET for residual tumour was 32.9% (specificity, 87.5%) and increased to 57.5% (specificity, 62.5%) at a threshold SUV of 1.5. Conventional imaging modalities were more sensitive in identifying residual tumour, but had a low corresponding specificity; sensitivity and specificity were as follows: MRI 97.6 and 40.0%, mammography 92.5 and 57.1%, ultrasound 92.0 and 37.5%, respectively. Breast MRI provided the highest accuracy (91.3%), whereas FDG-PET had the lowest accuracy (42.7%). CONCLUSIONS: FDG-PET does not provide an accurate assessment of residual tumour after primary chemotherapy of breast cancer. Magnetic resonance imaging offers the highest sensitivity, but all imaging modalities have distinct limitations in the assessment of residual tumour tissue when compared with histopathology.

A Folate Receptor-α–Specific Ligand That Targets Cancer Tissue and Not Sites of Inflammation

“…This specificity should allow facile differentiation of proximal malignant from inflamed regions of the same organ or tissue. The improved specificity could prove useful when recurrence of cancer is suspected near the site of a prior surgery and standard imaging methodologies cannot distinguish between the inflammation caused by the surgery and any residual malignant disease (32). This specificity might also be beneficial to autoimmune disease patients who have undergone prolonged treatment with immunosuppressant.…”

Baseline Tumor 18F-FDG Uptake and Modifications After 2 Cycles of Neoadjuvant Chemotherapy Are Prognostic of Outcome in ER+/HER2− Breast Cancer

“…However, evaluation at the end of NAC cannot provide the opportunity to change treatment. Moreover, studies that investigated PET performance at different time points showed that PET has a lower sensitivity to predict residual disease when performed at the end of chemotherapy (11).…”

18F-FDG PET/CT to Predict Response to Neoadjuvant Chemotherapy and Prognosis in Inflammatory Breast Cancer

“…In the present study, comparison of PET/CT to morphologic imaging results was not performed, because patients had either CT or MR imaging at the initial work-up. 18 F-FDG PET/CT has been used to assess response to NACT in non-IBC patients (7,10,(17)(18)(19)(20)(21)(22). Published data show a higher baseline 18 F-FDG uptake in patients with pCR than in patients with a poorer response (7,17).…”

“…Several studies have also evaluated the performance of 18 F-FDG PET/CT after completion of NACT to predict pCR (21,22) and found that 18 F-FDG PET did not accurately assess residual tumor. Similar results were observed in the present study, as mean SUV max on PET3 did not significantly differ between the pCR and nonpCR groups.…”