SERUM YKL-40 - A NEW POTENTIAL MARKER OF PROGNOSIS AND LOCATION OF METASTASES OF PATIENTS WITH RECURRENT BREAST-CANCER

YKL-40 is a recently discovered glycoprotein which is related in amino acid sequence to the chitinase protein family, but has no chitinase a ctivity. Although the function of YKL-40 is presently unknown, the pat tern of its expression by some tissues suggests that YKL-40 could func tion in tissue remodelling. The diagnostic features and relation to su rvival of serum YKL-40 have not been examined previously in human mali gnancies. In the present study YKL-40 was measured in serum obtained f rom 60 patients at the time that breast cancer recurrence was suspecte d. The median serum YKL-40 in patients with visceral or bone metastase s was 328 and 157 mu g/l, respectively and significantly higher compar ed to controls (99 mu g/l, P < 0.001). Kaplan-Meier survival curves de monstrated that survival, rates after 18 months were 24% for patients with high serum YKL-40 (>207 mu g/l = the 95 percentile of controls) a nd 60% for patients with normal serum YKL-40. The significance of the difference between the shorter survival of patients with high serum YK L-40 and the longer survival of patients with normal serum YKL-40 was high (P < 0.0009). When evaluated with other prognostic factors of sur vival after recurrence of breast cancer, serum YKL-40 and serum lactat e dehydrogenase (LDH) were the most significant independent factors. T he results indicate that determination of serum YKL-40 can be used as a prognostic marker related to the extent of disease and survival of p atients with recurrence of breast cancer. In addition, the serum YKL-4 0 level may be of value in the follow-up of patients with breast cance r and in evaluating potential metastatic spread.