Serum phosphodiesterase I activity in breast cancer patients

Serum phosphodiesterase I (PDE I) activity was determined in 13 control and 51 breast-cancer patients with various stages of disease. Patients with both localized and metastatic breast cancer had significantly elevated serum PDE I activity. The highest activity was seen in patients with liver metastases. A decline in serum PDE I activity was seen after surgical resection of all known disease.