Biological changes in breast cancers during tumor progression can affect therapeutic parameters, such as hormone receptors. We studied a series of primary tumors and the matching recurrent lesions to analyze the frequency of this phenomenon and the impact on disease-free interval. The expression of ER, PgR, c-erbB2, CD44v6, and p53 in the primary and the locoregional tumor was analyzed in 70 patients with recurrent breast cancer. Antigen expression correlated well between the primary and the matching recurrent tumor for all antigens under study. However, hormone receptor expression was lost in more than 50% of the cases, without significant impact on the disease-free survival interval. The disease-free interval was significantly longer for PgR-positive primary tumors, but did not depend on the ER status. The expression or changes of c-erbB2, CD44v6, and p53 were not related to the recurrence-free time intervals. Therefore, for treatment, it seems important to consider a possible loss of hormone receptors during tumor progression.