Response to second-line hormone treatment for advanced breast cancer. Predictive value of ploidy determination

Twenty-two patients who previously responded to first-line hormonal therapy were evaluated for factors which would predict for response to second hormonal manipulation. Investigations performed at progression after initial hormone response included immunocytochemical estimation of estrogen and progesterone receptors as well as flow cytometric analysis of tumor ploidy. Approximately 50% of patients were found still to be estrogen receptor positive at relapse from first-line hormone treatment. Progesterone receptor had, however, usually become negative. Nine of the 22 patients responded to second-line hormonal therapy. Second hormone responses occurred with equal frequency among hormone receptor-positive and hormone receptor-negative patients. Tumor ploidy, as determined by flow cytometric study did, however, predict for response. Eight of 12 patients with diploid tumors responded to second-line hormone therapy whereas only one of ten with aneuploid tumors responded. Flow cytometric analysis appears to be a promising technique for prediction of second hormone response after relapse from first-line hormone manipulation.