[Indoleamine 2, 3-dioxygenase activity for breast cancer patients with recurrence 5 or more years after surgery].

We evaluated the significance of indoleamine 2, 3-dioxygenase( IDO) in breast cancer patients with recurrence 5 or more years after surgery. IDO activity can be measured by the tryptophan (Trp)/kynurenine (Kyn) ratio. Trp and Kyn were measured by high-performance liquid chromatography( HPLC). We encountered 32 patients in whom breast cancer recurred 5 or more years after surgery. The mean age of the patients was 56.8 years. The mean duration of years since the initial treatment for breast cancer was 9.3±3.8 years. The rate of hormone receptor positivity was 93.8%. Twelve patients were suitable for locoregional therapy and the remaining 20 patients required chemotherapy. The patients suitable for locoregional therapy had a better prognosis than those who required chemotherapy. The correlation of the Trp/Kyn ratio between these 2 groups (locoregional therapy group and chemotherapy group) was studied. The Trp/Kyn ratio was higher in patients suitable for locoregional therapy than in those who received chemotherapy. The prognosis was better in patients with a high Trp/Kyn ratio than in those with a low Trp/Kyn ratio. These results suggest that determining the Trp/Kyn ratio was useful in the prognosis of patients with breast cancer that recurred 5 or more years after surgery.