Table 2. Metabolic markers for the early diagnosis of lung cancer.

Metabolite	Sample type	Function	References
Glycerol, phosphoric acid	Bronchoalveolar lavage fluid	Discriminate lung cancer patients and healthy controls	[5]
Hydroxylamine, threonine	Serum	Progression of lung cancer	[6]
Monopalmitin, benzyl alcohol	Expiration concentrate	Discriminate lung cancer patients and healthy controls	[7]
Phosphatidyl ethanolamine	Serum	Discriminate malignant and benign pulmonary nodules	[8]
Putrescine, cysteamine	Sputum	Discriminate lung cancer patients and healthy controls	[9]
Glutamic acid, choline, threonine	Serum	Discriminate non-small cell lung cancer patients and healthy controls	[10]
Threonine, acetic acid, acetone	Expiration concentrate	Differentiate lung cancer patients and healthy controls	[11]
Lactic acid, inositol, valine	Tissue	Discriminate malignant and benign pulmonary tissues	[12]
Choline, carnitine	Tissue	Discriminate lung cancer tissues and normal tissues	[13]
Diethyl spermine	Serum	Discriminate non-small cell lung cancer patients and healthy controls	[14]
Glutamic acid, aspartic acid, xylose	Serum and plasma	Discriminate lung adenocarcinoma patients and healthy controls	[15]
Phosphorylcholine, sphingosine	Serum	Discriminate lung cancer patients and healthy controls	[16]
Glycerol, lactic acid, tryptophan	Plasma	Discriminate non-small cell lung cancer patients and normal persons	[17]
Benzoic acid, lactic acid, glucose	Plasma	Discriminate lung cancer patients, smokers and non-smokers	[18]
Glucose, cysteine, glucosamine	Tissue	Discriminate malignant and benign pulmonary tissues	[19]
Bilirubin	Serum	Predict the lung cancer risk in smokers	[20]
Octanedioic acid, tetrahexose	Sweat	Discriminate lung cancer patients and normal persons	[21]
Hydroxybutyrate, alanine	Cerebrospinal fluid	Distinguish lung cancer leptomeningeal metastases	[22]
Citric acid, choline, lysine	Serum	Discriminate non-small cell lung cancer and chronic obstructive pulmonary disease	[23]
Choline, linoleic acid	Serum	Discriminate lung cancer patients and normal persons	[24]
Carnitine, acetylcarnitine	Urine	Discriminate non-small cell lung cancer patients and normal persons	[25]
Creatine ribonic acid, acetylneuraminic acid	Urine	Discriminate non-small cell lung cancer patients and normal controls	[26]
Alanine, threonine, linoleic acid	Plasma	Discriminate lung adenocarcinoma patients and normal persons	[27]
Citric acid, choline, leucine	Serum	Discriminate lung cancer and chronic respiratory disease	[23]
Linoleic acid, hydroxy isobutyric acid	Serum	Discriminate lung cancer patients and normal persons	[28]
Glutamic acid, erythritol, palmitic acid	Plasma	Discriminate small cell lung cancer patients and healthy controls	[29]
Alanine, valine, isoleucine	Plasma	Discriminate non-small cell lung cancer patients and normal persons	[30]
Hippuric acid, hydroxy isovaleric acid, creatinine	Urine	Discriminate lung cancer patients and healthy controls	[31]
Tryptophan, hippuric acid, threonine	Urine	Discriminate lung cancer patients and normal persons	[32]
Taurine, hippuric acid, carnitine	Urine	Discriminate lung cancer patients and normal persons	[33]
Carnitine, propionylcarnitine, tyrosine, methionine, malic acid, histidine, 5-oxo-proline	Serum	Discriminate non-small cell lung cancer patients and normal persons	[34]
Glucose, tyrosine, glycerol, valine	Serum	Discriminate lung cancer patients and non-cancer patients	[35]
Benzaldehyde, urea, isoleucine, glycolic, phenylalanine	Serum	Discriminate early stages of lung cancer patients and normal persons	[36]