Dramatic regression of multiple brain metastases from breast cancer with Capecitabine: another arrow at the bow?

Several chemotherapic agents, which are active against breast cancer, penetrate poorly into the central nervous system. Despite its limited brain penetration, 5-fluorouracil has been a component of effective regimens for brain metastases. Capecitabine is a recently developed oral prodrug that is converted into 5-fluorouracil by sequential enzymatic steps. Thymidine phosphorylase (TP) is the final enzyme responsible for Capecitabine activation. Studies have demonstrated that high intratumoral levels of TP and low levels of its catabolite dihydropyrimidine-dehydrogenase are correlated with the capecitabine response. The penetration of Capecitabine across the brain-blood barrier remains unknown; we report the case of and discuss a breast cancer patient who had an interesting response of brain metastases with Capecitabine in monochemotherapy before brain irradiation.