Long-term survival is linked to serum LDH and partly to tumour LDH-5 in NSCLC.

BACKGROUND Lactate formation is up-regulated in tumorous cells by lactate dehydrogenase (LDH). High serum LDH level is linked to many malignancies with poorer survival, but tumour LDH-5 has not been well investigated in non-small cell lung cancer (NSCLC). PATIENTS AND METHODS In 89 patients operated on for NSCLC stage I-III, the serum LDH level was assayed and immunohistochemistry for tumour LDH-5 was performed. Impact on long-term survival and correlation was analysed. RESULTS High serum LDH was associated with poorer survival (p<0.001). No correlation was revealed between serum LDH and the tumour LDH-5. Only in tumours greater than 3 cm were high tumour LDH-5 values associated with higher serum LDH values (p=0.04) and in this subgroup, high tumor LDH-5 was associated with poorer long-term survival (p=0.024). CONCLUSION High serum LDH has a negative impact on long-term survival in NSCLC, whereas for tumour LDH-5, this was seen only in a subgroup of patients with larger tumours.