Utility of plasmatic levels of alpha-1-antiprotease (A1AP) as a cancer marker.

The objective of this study was to evaluate the diagnostic utility as a cancer marker of plasmatic levels of A1AP. This case-control study included 135 cancer patients from different sites, confirmed histologically, and 95 controls (57 normal individuals plus 38 chronically ill patients with non-tumoral diseases). Determination of A1AP was done by a nephelometric procedure using a laser nephelometer as the measuring instrument. There were no sex or age related variations in plasmatic A1AP. Mean values of A1AP in 57 normal controls was 2.87 milligrams (95% C.I., 2.58-3.15); in 95 non-tumoral individuals, including 38 chronic non-malignant diseases plus 57 normal controls, 3.09 milligrams (2.46-3.72) and in malignant tumors, 4.12 milligrams (3.80-4.45). There was a statistically significant difference between chronic diseases and normal controls (P < 0.05) and also between cancer patients and non-tumoral individuals, normal control and chronic non-tumoral diseases (P < 0.001). The means of plasmatic A1AP by tumoral site are increasing in this order: breast, gastrointestinal, head and neck, and lung. The means by clinical stage are increasing in this order: complete remission, local disease, local-regional disease and metastatic disease. The calculated cutoff value, excluding complete remission cases, is 3.37 milligrams, with sensitivity 67.7% and specificity 67.7%. We conclude that there is an increase of plasmatic A1AP in cases of clinically active cancer compared with normal controls and normal range values in clinical complete remission. It can be an acceptable cancer marker that discriminates cancer from chronic non-tumoral diseases and complete clinical remission from relapses.