Elevation of serum placental alkaline phosphatase levels in cigarette smokers

In an ongoing longitudinal study for tumor markers in breast cancer patients, levels of placental alkaline phos‐phatase (PAP) measured by RIA were found to be elevated in 34% of patients who smoked cigarettes as opposed to 5 % of non‐smoking subjects. A normal range was established (0‐2.14 ng/ml) using healthy non‐smoking females. In an expanded analysis by disease state, PAP levels were found to be elevated significantly (p<0.02) in the smoking groups of each category. This isoenzyme, when detected at elevated serum levels by RIA, was enzymatically active in 48% of the patients as analyzed by immunoenzymatic assay. One smoker with high PAP levels discontinued smoking following a myocardial infarction. Her PAP levels returned to normal within 2 months.