Elevated lactic acid is a negative prognostic factor in metastatic lung cancer

BACKGROUND: Hyperlactatemia with or without type B lactic acidosis is a rare complication of cancer, previously observed most often in hematological malignancies. The aim of this study was to assess the prognostic value of lactic acid (LA) in patients with metastatic lung cancer. METHODS: Patients diagnosed with stage IV non-small cell lung cancer (NSCLC) and extensive stage small cell lung cancer (SCLC), were included in this single center retrospective study. Arterial and venous LA level, anion gap (AG), serum LDH and presence of urine ketones were recorded for each patient and their associations with demographic and clinical data and overall survival (OS) were examined. RESULTS: Eighty-five patients (43 males, median age 74, range 45-96 years) were studied. The maximal levels of arterial or venous LA were significantly associated with presence of >= 2 metastatic sites (p = 0.001), ICU admission or transfer (p = 0.016), intubation (p = 0.029), elevated serum anion gap (p < 0.001) and LDH levels (p < 0.001). Hyperlactatemia (>= 1.4 mmol/L) was associated with shorter OS (log-rank p < 0.001). In a multivariate model including LA, ICU, intubation, AG as well as other known prognostic factors of NSCLC and SCLC, including age, sex, smoking status, number and location of metastases, histologic type, performance status (PS), chemotherapy and LDH, LA retained its prognostic value (OR: 1.3; 95% CI: 1.082-1.561; p = 0.005), along with PS (p = 0.039) and chemotherapy (p = 0.039). CONCLUSIONS: The results of the study suggest that a high lactic acid level (>= 1.4 mmol/L) is associated with significantly shorter overall survival in patients with metastatic non-small cell lung cancer and extensive stage small cell lung cancer. Hyperlactatemia is an independent predictor of poor survival in metastatic lung cancer patients.