[Serum alkaline phosphatase flare in prostate cancer accompanied by bone metastases and treated with hormonal therapy. TEKK Study Group].

To clarify the roles of alkaline phosphatase (ALP) flare in prostate cancer accompanied by bone metastases and treated with hormonal therapy, we evaluated the clinicopathological character, treatment efficacy and outcome for patients with and without ALP flare. We evaluated 60 patients with newly diagnosed prostate cancer accompanied by bone metastases and treated with hormonal therapy, whose response in terms of serum prostate specific antigen (PSA) levels showed a partial response (PR) or better response. The patients were classified into two groups, an ALP flare group (13 cases) and a non-ALP flare group (47 cases). The former showed serum ALP elevation of more than double, and the latter less than double that of pretreatment levels following hormonal therapy. Patient characteristics, PSA response and outcome were compared between the two groups. Extent of disease (EOD) as grade of bone metastasis was significantly higher in the ALP flare group than in the non-flare group (p = 0.0352). Pre-treatment serum PSA levels were also significantly higher in the ALP flare group (p = 0.0010). However, there were no significant differences in pretreatment serum ALP levels. Serum PSA levels were normalized in 37 of the 47 patients (78.7%) in the non-ALP flare group compared with 6 of the 13 (46.2%) in the ALP flare group (p = 0.0211). Moreover, the period until biochemical failure was significantly shorter for the ALP flare than the non-flare group (p = 0.0027). These results suggest that prostate cancer patients with bone metastases in whom ALP flare is observed in response to hormonal therapy tend to have more extensive bone metastases, high pretreatment PSA levels, to be resistant to PSA normalization and more likely to experience biochemical failure.