TRANSIENT INCREASE IN TOTAL SERUM ALKALINE-PHOSPHATASE PREDICTS RADIOLOGICAL RESPONSE TO SYSTEMIC THERAPY IN BREAST-CANCER PATIENTS WITH OSTEOLYTIC AND MIXED BONE METASTASES

Assessment of the response of bone metastases to endocrine or chemothe rapy is difficult, and true response rate is probably underestimated b y UICC criteria. Biochemical markers of osteoblast activity, which is linked with bone healing, could be useful for early detection of treat ment response. We studied changes in osteoblast function, assessed by serial serum total alkaline phosphatase (tALP) at 0, 1, 2, 3 months fr om the start of systemic therapy, in 31 patients bearing bone metastas es from advanced breast cancer. After 1 month of endocrine or cytotoxi c treatment, all responding patients (7/31) showed a significant rise in tALP (mean increase: 351 IU/l, p < 0.05) followed by a gradual decr ease over the subsequent months (tALP flare). Transient increase in tA LP was also found in 2/16 patients with stable disease who benefited f rom therapy. 2/8 patients with progressive disease showed a rise indis tinguishable from responders, but the subsequent decrease was not appa rent. These observations suggest that serum tALP profile is an earlier predictor of response than X-rays.