Measurement of serum N-acetyl beta glucosaminidase activity in patients with breast cancer

N-acetyl-beta-glucosaminidase (NAG) activity measured in sera from 129 brea st cancer patients was elevated (mean 18.2 units/l) compared with that in s era from 28 healthy women (11.6 units/l) (p = 0.001). There was a weak corr elation between NAG activity and carcinoembryonic antigen (CEA) and CA-153, but no relationship to age, menopausal status. node status. stage, histolo gy of tumour or to steroid receptors. NAG, CEA and CA-153 were measured in periodic follow-up samples taken after surgery (up to 26 months) from 17 pa tients. NAG activity fluctuated within a narrow range, unlike CEA and CA-15 3. In 70% of cases the pattern was similar to at least one of the other mar kers, and was generally maintained at a higher level in patients who suffer ed relapse compared with those who remained disease-free up to the last fol low-up, but was not significantly altered before relapse. The measurement o f NAG activity is unlikely to be of value in predicting time or occurrence of relapse or of clinical utility in post-surgical therapy. Increased appea rance in serum may aid metastasis by degrading the extracellular matrix and it may be better investigated as a predictor of progression from in situ t o invasive and metastatic cancer.