Capecitabine in Metastatic Breast and GI Cancers

Goals of treatment of metastatic breast cancer remain largely comfort care. However, there has been improvement in median survival among women with metastatic disease over the last two decades, mainly due to availability of more effective agents. Women are now living longer with metastatic disease and are on therapy for longer periods of time. Therefore, it is increasingly important for effective therapies to be associated with less toxicity so that women can enjoy a better overall quality of life. Similar to breast cancer, goals of treatment of various GI malignancies (including metastatic colorectal cancer, metastatic gastric and esophageal cancers, and unresectable or metastatic pancreatic cancer and cholangiocarcinoma) are largely comfort care and it is important to minimize toxicity from therapy during the treatment for metastatic disease. Capecitabine is a unique chemotherapeutic agent for two reasons. It is the only oral chemotherapy drug available to treat breast and GI malignancies, making it convenient for patients. In addition, whereas all other cytotoxic chemotherapy agents can be administered for only a few months at a time because of development of cumulative toxicities, capecitabine can be continued for many months to years if toxicities can be managed. However the optimal dosing schedule of capecitabine is not known. This is the basis for the proposed randomized phase II trial, to compare the efficacy and tolerability of capecitabine 1500 milligrams (mg) twice a day (BID), 7 days on and 7 days off schedule to capecitabine 1250 milligrams/meters squared (mg/m2) BID, 14 days on and 7 days off) or 1000 mg/m2 BID, 14 days on and 7 days off, in women with metastatic breast cancer or patients with advanced/metastatic GI cancer.