Biological markers in breast carcinoma—clinical correlations with pseudouridine, n2,N2‐dimethylguanosine, and 1‐methylinosine

Urinary levels of the minor nucleosides, pseudouridine (psi),N2, N2-dimethylguanosine (m22G), and 1-methylinosine (m1I), were investigated in patients with breast carcinoma. Elevated levels of psi were observed in 27/131 (20.6%) patients with metastatic disease, 1/14 (7.1%) preoperative patients, and 1/28 (3.6%) postoperative N+ patients. Elevated levels of m22G and M1I were observed, respectively, in 46/131 (35.1%) and 274131 (20.6%) patients with metastatic disease, 3/14 (21.4%) and 3/14 preoperative patients, and 6/28 (21.4%) and 2/28 (7.1%) postoperative N+ patients. There was no correlation between nucleoside levels and involvement of specific organ sites with metastatic disease, nor with chemotherapy response rate or time to treatment failure. During the treatment of metastatic disease there was a tendency for elevated pretherapy psi levels to decrease with attainment of a response and, if the levels subsequently rose to be associated with treatment failure. However, increasing levels of m22G and 71I occurred with both response and disease progression. These results suggest that routine measurement of the level of the urinary nucleosides would be of limited value for following the disease course in patients with breast cancer.