Trial Information

Randomized Control Study of Capecitabine vs. S-1 in Unresectable or Recurrent Breast Cancer Patients

The incidence of breast cancer is increasing in Japan: 33,676 women were diagnosed with
breast cancer in 2001, making it the leading cause of cancer among women since 1995.
Statistical database in Exel format/outline of health welfare statistics from the Ministry
of Labor, Health, and Welfare show that the number of deaths from breast cancer was 9,806 in
2003. Because the ten-year survival rate is about ninety percent in Stages 0 and I breast
cancer patients, detection and treatment at an earlier stage can lead to higher survival
rates. However, the recurrence rate increases as the disease progresses. In addition, about
thirty percent of all breast cancer patients are believed to have recurrent disease. Thus,
developing treatments against recurrence may be an important task.

The Guideline for Breast Cancer Treatment, 2004 version, recommends chemotherapy, including
anthracyclines or taxanes as a first-line chemotherapy for metastatic or recurrent (grade B
recommendation) breast cancer. In a second-line therapy recommended for metastatic or
recurrent diseases, the Guideline reports that a combination of capecitabine, a 5Fu
derivative (an oral chemotherapy of pyrimidine fluorides approved in 2003) with docetaxel is
superior to docetaxel alone for improving survival. This regimen is recommended for patients
with cardiac malfunction who cannot be treated with anthracyclines (grade B recommendation).
However, data are lacking to support capecitabine as a standard regimen as a second-line
therapy; its efficacy needs verification and further study. Accordingly, this study is
designed to investigate the efficacy and safety of S-1 alone, an oral pyrimidine fluoride,
to which an indication of "inoperable or recurrent breast cancer" was added, as a first-line
therapy in patients with inoperable or recurrent breast cancer by comparing it with
Capecitabine alone, which is already approved of the same indication.