Serum midkine levels are increased in patients with various types of carcinomas

The level of expression of midkine (MK), a heparin-binding growth factor, i s increased in many types of human carcinomas. An enzyme-linked immunoassay , which utilizes a combination of rabbit and chicken antibodies revealed th at serum MK level in the controls (n = 135) was 0.154 +/- 0.076 (mean +/- S D) ng ml(-1) with an apparent cut-off value as 0.5 ng ml(-1). Serum MK leve l was significantly elevated in the cancer patients (n = 150) (P < 0.001); 87% of the patients showed levels of more than 0.5 ng ml(-1). All ten types of cancer examined showed a similar profile of serum MK level. There was n o or weak correlation between C-reactive protein level, a marker of inflamm ation, and serum MK level. Furthermore, in case of gastric carcinoma and lu ng carcinoma, patients with stage I carcinoma already showed elevated serum MK levels. The present results indicated that serum MK could serve as a ge neral tumour marker with a good potential for clinical application. (C) 200 0 Cancer Research Campaign.