Abstract
A sequential study of urinary hydroxyproline was performed in 47 patients with cancer of the breast. The results have shown that hydroxyproline excretion in the urine provides a sensitive index of the early development of secondary deposits in bone from primary breast cancer. Elevation of the urinary excretion of hydroxyproline may predate by several months the radiological demonstration of osseous deposits. Sequential estimations have shown that the elevated urinary hydroxyproline excretion is persistent in patients who subsequently develop deposits in bone.