Clinical significance of pyrimidine nucleoside phosphorylase (PyNPase) in breast cancer

To clarify the clinical significance of pyrimidine nucleoside phosphorylase (PyNPase) activity in breast cancer, we examined the possible correlation of PyNPase activity to clinicopathological features and prognosis in twenty-one patients with primary breast cancer from April 2000 to December 2001. Flow signals of tumors were analyzed by Power Doppler sonography (PDUS), and maximal velocity (V(max)) was calculated. PyNPase activity of resected specimens was assayed by ELISA method. PyNPase activities in resected cancerous tissue were 156.9+/-63.5 unit/mg (mean+/-SD), which were significantly higher than that in normal tissue (19.0+/-18.1 unit/mg, p<0.0001). PyNPase activity was positively correlated with tumor size (r=0.496, p=0.026) and V(max) (r=0.498, p=0.021). The disease free survival rate was significantly lower in the high PyNPase activity group than in the low PyNPase activity group. In overall survival rate, there was no significant difference between the high and low PyNPase activity groups. In the multivariate analysis, PyNPase activity was an independent predictor of postoperative recurrence (p=0.032). We suggest that PyNPase activity is associated with progression and proliferation of breast cancer, and that it may be useful for prediction of the prognosis.