[A case of stage IV breast cancer responding to S-1 therapy after FEC and PTX therapies].

In November 2005, a 34-year-old female presented to our department with a bleeding tumor on her right breast. She noticed the tumor approximately two years ago but she left it untreated. An exposed tumor was observed with a diameter of approximately 8 cm located in the right breast. It was diagnosed as invasive ductal carcinoma by biopsy (ER (+), PgR (+), and HERS2: 1 +). The imaging showed multiple metastases to the bilateral lungs, right axillary lymph node, mediastinal lymph node and sternal. The diagnosis was made as right breast cancer (T4c, N3c, M1, and stage IV). The patient received 4 courses of FEC therapy and 4 courses of PTX therapy. The patient had a partial response (PR). However, tumor markers were elevated in September 2006. Thus, an administration of S-1 was initiated. The size of the tumor shown in the imaging was reduced, and the patient had a PR. Since December 2008, tumor markers have been elevated again. However, the patient has had SD in the imaging and S-1 administrations have been continued. A total of 24 courses have been performed to the present time, and the patient's conditions have not been aggravated in approximately 3 years and 5 months. She has maintained a good QOL and is being followed up on an outpatient basis. S-1 administrations can be an effective treatment for advanced breast cancer resistant to anthracycline and taxane when considering a satisfactory QOL of patients.