Application of quantitative analysis to biologic profile evaluation in breast cancer

The biologic profile of 907 infiltrating breast carcinomas was determined considering estrogen receptor (ER) and progesterone receptor (PR), proliferation index (PI) and c-erbB-2/Neu expression. The relationship with pathologic parameters (lymph node status, size, histotype) were studied by a multivariate analysis. The clinical prognostic power of biologic profile also was evaluated for 265 patients.

In 907 infiltrating breast carcinomas, the quantitation of ER, PR, an PI was obtained with an image analysis system (CAS 200, Becton Dickinson Cell Analysis Systems, San Jose, CA); Neu was evaluated semiquantitatively. A clinical study of 265 patients was performed (median follow-up, 42.5 months).

Seventy-seven percent of tumors were ER-positive, 70% were PR-positive, 58% had a high PI, and 35% were Neu-positive. The overall analysis indicated a direct correlation between ER and PR (Spearmans' rho [rs] = 0.47, P < 0.001) and an inverse correlation between PI and ER (rs = -0.39, P < 0.001), PI and PR (rs = -0.32, P < 0.001), Neu and ER (rs = -0.20, P < 0.001), and Neu and PR (rs = -0.21, P < 0.001). Cluster analysis, performed based on the biologic profile (ER, PR, PI, c-erbB-2/Neu expression), identified two final groups of tumors with different pathologic features. This study showed a longer relapse free interval for patients with ER- and PR- positive tumors (P = 0.016 and P = 0.007) and low PI and Neu-negative tumors (P < 0.001 and P = 0.047).

These results stress the importance of the biologic profile for defining tumor behavior and patient management, leading to integration of, and eventually the substitution for, the actual staging system.