Distribution of plasma-bound hydroxyproline in breast cancer, benign breast disease and healthy females.

In normal adult females, patients with benign breast disease and patients with breast cancer, hydroxyproline (OHPro) was found in the plasma attached to the protein fractions which were separated by Sephadex gel filtration. In addition, a distinct moiety, probably a protein sub-unit, containing substantial amounts of this imino acid, occurred in between gel filtration fractions III and IV. Quantitative differences in the OHPro content of these various fractions were observed in the groups of patients studied. Significant elevations in the peptide-bound OHPro (fraction IV) were found only in patients with breast cancer and the level appeared to correlate with the degree of advancement of the disease. Similar findings relate to the OHPro content of the sub-protein moiety which is found between gel filtration fractions III and IV. A reduced level of high molecular weight hyproprotein (fraction I) was found in the breast cancer group.