[Capecitabine: an oral chemotherapeutic agent against metastatic breast and colorectal cancer]. / Capecitabina: un quimioterápico oral en la lucha contra el cáncer de mama y colorrectal metastásico.

Capecitabine is the first drug in a new fluoropyrimidine class that offers distinct characteristics. On one hand its oral administration mimics continuous fluorouracil infusion while remaining convenient with higher patient acceptance and compliance rates and avoiding intravenous administration-associated complications and financial costs. On other hand it provides intra-tumour selective activation, thus potentially facilitating local management and therefore improved anti-tumour activity as well as reduced systemic toxicity. The concentration of thymidine phosphorylase an enzyme essential for capecitabine activation in tumour cells increases after exposure to cytotoxics such as taxanes, cyclophosphamide, gemcitabine or vinorelbine, which results in synergistic activity. It has been tried both as monotherapy and in combination with other chemotherapy agentsâboth in first-line regimes and in previously treated patients against metastatic colorectal and breast cancer, results being very good in terms of efficacy and tolerability.