CHANGES IN CELL-KINETICS INDUCED BY PRIMARY CHEMOTHERAPY IN BREAST-CANCER

Changes in the H-3-thymidine labelling index (H-3-TdR LI) of primary tumour induced by cytoreductive chemotherapy were evaluated in 26 patients with locally advanced breast cancer subjected to mastectomy after different systemic therapies. A significant reduction of H-3-TdR LI by primary chemotherapy was observed in 11 cases. Changes in cell kinetics were related to the pretreatment proliferative activity: significant increases were observed in 70% of tumors with a very low H-3-TdR LI(< 2.5%) and significant decreases in 100% of tumors with a very high H-3-TdR LI ( > 7.0%). There was no correlation between pretreatment H-3-TdR LI and the objective clinical response, which was conversely related to post-treatment cell kinetics. The 2-year progression rate was lower for patients whose residual tumors after treatment had remained (2/7) or become (1/8) slowly proliferating than for patients whose tumors had remained (5/7) or become (4/4) rapidly proliferating.