Total and nondialyzable hydroxyproline excretion in Stage D2 prostate cancer

Hydroxyproline is excreted in urine as a breakdown product of normal bone turnover: A dialyzable (D) fraction (90% of total) reflects active bone destruction and a nondialyzable (ND) fraction reflects bone growth/regrowth. In metastatic prostate cancer where blastic osseous metastases predominate, disease progression on bone scan correlated with elevation of both total hydroxyproline excretion (7.84 + 1.28, P less than 0.001) and the ND urinary level (0.94 +/- 0.20, P less than 0.01). In patients with a serially stable/improving scan, urinary excretion of each fraction (2.18 + 0.27 and 0.27 +/- 0.01) was similar to that of men with no evidence of disease. For Stage D2 prostate cancer, these two markers satisfactorily monitor osseous activity in the intervals between serial bone scintigraphy.