Monitoring early response to taxane therapy in advanced breast cancer with circulating tumor cells and [18F] 3′-deoxy-3′-fluorothymidine PET: a pilot study

Aim: Early markers of response to chemotherapy, measured by blood markers and imaging, may ultimately lead to tailored therapies that avoid cumulative toxicity. Materials & methods: We performed a small pilot study to compare early changes in levels of circulatory tumor cells (CTCs) with changes in tumor proliferation, using metabolic imaging with [F-18] 3'-deoxy-3'-fluorothymidine PET (FLT-PET) in women with advanced breast cancer, before and during docetaxel therapy. Results: In those individuals in whom we could detect CTCs, a decrease in CTC count correlated with a decrease in FLT-PET signal, within 2 weeks. Conclusion: Combined, these two technologies are likely to provide a powerful, albeit expensive, tool to assess immediate responses to therapy.