Cell kinetics as a prognostic marker in node-negative breast cancer.

The relevance of cell kinetics of the primary tumor as a marker of biologic aggressivity was verified on a series of 258 patients with operable breast cancer without nodal and distant metastases, who underwent radical mastectomy without any other treatment until relapse. The cell proliferative rate, evaluated in vitro on fresh tumor material and expressed as 3H-thymidine labeling index, was found to be an important discriminant of metastatic potential. Patients with slowly proliferating tumors showed a higher probability of 6-year relapse-free survival in comparison to those with fast-proliferating tumors (80.5% versus 59.6%, P = 0.00004). This finding was true for premenopausal and paramenopausal (P = 0.00005) as well as for postmenopausal patients (P = 0.01). The kinetic variable was also a discriminant of 6-year survival for the overall series (P = 0.003) and for premenopausal and paramenopausal patients (P = 0.003) regardless of the type of treatment after relapse. These findings show the relevance of the kinetic variable as an important prognostic marker in breast cancer.