Increased phosphotyrosine in breast cancer tissue is associated with a worse prognosis.

We have previously demonstrated that phosphotyrosine can be identified in breast cancer cells using an immunohistochemical stain. We have subsequently used this technique to characterize 106 women with breast cancer (46 with Stage 1 and 60 with Stage 2) who have been followed for at least four years by one oncologist. We analyzed all primary breast cancer tissue using immunohistochemical staining and the amount of phosphotyrosine (PT) was scored on a 0 to 3 range. The PT score of the primary tumor was unrelated to either breast cancer stage or estrogen and progesterone receptor analysis, as high PT scores were noted in both disease stages and all receptor categories. We did find that patients with either no or trace (1+) amounts of PT survived longer than those patients with higher amounts of PT. The patients with low PT had significantly lower chance of relapse (Chi Square = 15.8, p < 0.001) and a lower mortality (Chi Square = 13.1, p = 0.001). We conclude that immunohistochemical methods to determine the PT score may identify patients at higher risk for disease relapse independent of tumor stage or hormonal status.