Droloxifene-induced spikes of tumor markers predict benefit of therapy

In the clinical monitoring of cancer, tumor marker proteins may reflect the status of the disease. In cases with radio- and chemotherapy, spikes of tumor markers were found shortly after starting the therapy. These spikes were interpreted as a sign of tumor lysis. Recently during therapy of breast cancer with the new antiestrogen droloxifene, spikes of CA 125 and CA 15-3 were also found in about one-third of patients responding to therapy. The peaks of these initial increases were recorded between 14 and 60 days after the onset of treatment, with maximum concentrations up to 1,890% of the initial value. Marker concentrations decreased thereafter, to new baselines at or below the initial values. Objective clinical responses with measurable reduction of tumor mass were observed during the spikes. These results were never observed previously with other antiestrogen treatment and may be interpreted as lysis of tumor cells.