title: actate Dehydrogenase (LDH) as a Tumor Marker for Non-small Cell Lung Cancer.
abstract: OBJECTIVE
  To determine the prognostic value of pre- treatment serum LDH levels and the LDH isoenzyme pattern for non-small cell lung cancer, and to determine the relationship between the response to chemotherapy and the changes in serum LDH levels following chemotherapy.
  
  
  METHODS
  Patients with pathologically confirmed non-small cell lung cancer were entered onto this study. Their serum LDH levels were assessed prior to chemotherapy, with the LDH isoenzyme being assessed in patients with high initial serum LDH levels. The serum LDH levels were re-assessed following 2 cycles of chemotherapy. The relationship between the response to chemotherapy, pre-treatment serum LDH levels and LDH isoenzyme pattern and the changes in serum LDH levels, following chemotherapy, were evaluated.
  
  
  RESULTS
  49 patients were entered onto this study. The pre-treatment serum LDH levels were normal in 26 patients, and elevated in 23. The LDH isoenzyme was evaluated in 15 patients, with LDH2 being elevated the most frequently. The response rate to chemotherapy was 42.9% in all 42 patients able to be evaluated, 45.8% in patients with normal serum LDH levels and 41.2% in patients with elevated serum LDH levels. This difference was not statistically significant (p=0.767). The median survival was 37 weeks in all patients able to be evaluated, 38 weeks in those with normal serum LDH levels and 31 weeks in those with elevated serum LDH levels. These differences were not statistically significant (p=0.202). The patients with normal serum LDH levels following chemotherapy were more responsive to chemotherapy than those with elevated serum LDH levels following chemotherapy (response rate 51.4% vs. 0%, p=0.027).
  
  
  CONCLUSIONS
  The LDH2 are most commonly elevated in non small cell lung cancer patients. The pre-treatment serum LDH levels do not reflect the prognosis accurately. The serum LDH levels following chemotherapy are associated with the response to chemotherapy.
authors.forename: Young Jin
authors.initials: YJ
authors.lastname: Yuh
authors.forename: Sung Rok
authors.initials: SR
authors.lastname: Kim
keywords: LDH; Non-small cell lung cancer; Tumor marker