title: Serum YKL-40 levels as a prognostic factor in patients with locally advanced breast cancer.
abstract: BACKGROUND
  YKL-40 is a growth factor for connective tissue cells; it also stimulates the migration of endothelial cells. YKL-40 is secreted by cancer cells, and elevated serum levels have been associated with poorer prognosis in metastatic breast cancer. In the present study we evaluated the prognostic role of serum YKL-40 levels in patients with locally advanced breast cancer.
  
  
  METHODS
  YKL-40 levels were measured using ELISA in serum samples obtained from 45 breast cancer patients prior to surgery and chemotherapy. The median follow-up time was 46 months (range, 10-96 months). All patients underwent surgery after chemotherapy. During the follow-up period, 21 patients relapsed and there were 17 deaths.
  
  
  RESULTS
  The median serum YKL-40 concentration in patients with locally advanced breast cancer was 149.5 mug/l (range, 25.0-1021.3 microg/l). This was higher than levels observed in healthy female controls but the difference was not significant (P=0.44). Serum YKL-40 levels were also higher in patients with tumour size >2 cm and node-positive disease but again the differences were not significant (P>0.05). Tumour volume was correlated with serum YKL-40 levels (r=0.308, P=0.039). High serum YKL-40 levels were associated with shorter disease-free and overall survival although this trend failed to reach significance (P>0.05). Multivariate analysis including tumour size, lymph node status, oestrogen and progesterone receptor status, tumour grade, and serum YKL-40 levels indicated that serum YKL-40 levels were an independent prognostic variable for overall survival (hazard ratio, 1.004; 95% confidence intervals: 1.00, 1.07; P=0.027). Tumour size, lymph node status and oestrogen receptor status were also independent prognostic variables for overall survival (P<0.05).
  
  
  CONCLUSIONS
  Our results show that serum levels of the growth factor YKL-40 may be a useful prognostic indicator of outcome for patients with locally advanced breast cancer. Further studies are required to fully elucidate the biological function of YKL-40 in breast cancer.
authors.affiliation: Department of Medical Oncology, Gazi University Medical School, Ankara, Turkey.
authors.forename: Deniz
authors.initials: D
authors.lastname: Yamac
authors.forename: Banu
authors.initials: B
authors.lastname: Ozturk
authors.forename: Ugur
authors.initials: U
authors.lastname: Coskun
authors.forename: Ercument
authors.initials: E
authors.lastname: Tekin
authors.forename: Banu
authors.initials: B
authors.lastname: Sancak
authors.forename: Ramazan
authors.initials: R
authors.lastname: Yildiz
authors.forename: Can
authors.initials: C
authors.lastname: Atalay
mesh_terms: D054392:Adipokines; D014408:Biomarkers, Tumor / Q000097:blood*; D001943:Breast Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000401:mortality; D000071451:Chitinase-3-Like Protein 1; D018572:Disease-Free Survival; D005260:Female; D006023:Glycoproteins / Q000097:blood*; D006133:Growth Substances / Q000097:blood*; D006801:Humans; D037102:Lectins; D011379:Prognosis; D015996:Survival Rate
chemical_list: D054392:Adipokines; D014408:Biomarkers, Tumor; C084533:CHI3L1 protein, human; D000071451:Chitinase-3-Like Protein 1; D006023:Glycoproteins; D006133:Growth Substances; D037102:Lectins