Proliferation-associated Nucleolar Antigen P120: a Prognostic Marker in Node-negative Breast Cancer

Background: P120 is a nucleolar proliferation antigen found in rapidly dividing cells and in a variety of malignancies.

Methods: Our purpose was to determine whether P120 expression is a prognostic factor for patients with node-negative breast cancer by testing pathologic material from 90 patients for P120 immunoreactivity, histologic grade, and estrogen receptors.

Results: P120 was detected in 52 of the 90 specimens (58%). Node-negative cancer patients with tumors that did not express the P120 antigen had a significantly better overall survival rate than node-negative cancer patients with tumors that did express P120 (92% vs 69%; p = 0.035). Histologic studies indicated that 36 tumors were grade I, 28 were grade II, and 26 were grade III. The presence of P120 correlated significantly with the nuclear grade of the tumor: 73% of grade III tumors, 64% of grade II tumors, and 42% of grade I tumors stained positive for P120 (p = 0.033). The correlation between nuclear grade and overall survival rate was also significant (grade 1, 94%; grade II, 79%; grade III, 58%); (p = 0.003). No significant correlation was found between P120 expression and estrogen receptors. Multivariate analysis shows that P120 expression and histologic grade together are the strongest predictors of survival.

Conclusions: The biologic marker P120 may play an important role in determining which patients with node-negative cancer will benefit most from adjuvant therapy.