The postabsorptive hydroxyproline in the long-term evaluation of patients with breast cancer.

The postabsorptive urinary hydroxyproline excretion test (Spot-HYPRO) was evaluated for its usefulness in reflecting the presence or absence of bone metastasis in 75 women with breast cancer. A comparison was made between the Spot-HYPRO values and bone disease, as documented by bone scanning supported by skeletal x-rays. Breast cancer patients with skeletal metastasis had 3-4-fold elevations in Spot-HYPRO above the control values (P less than 0.001). Mild elevations were noted in breast cancer patients without skeletal metastasis (P less than 0.025). Thirty patients received serial Spot-HYPRO and bone scans for 6 to 48 months (average, 24 months). There was a 90% correlation between changes in Spot-HYPRO and simultaneous changes on bone scan. Elevations in Spot-HYPRO preceded changes found on bone scan by an average of 3 months. The authors conclude that the Spot-HYPRO is a simple, convenient, and accurate method of documenting and following bone metastasis in patients with breast cancer.