The purpose of this study is to determine if pyruvate kinase M2 (PKM2) can be used as a biomarker in cancer.

Pyruvate kinase M2 is more elevated in malignant pleural fluid than in plasma, and may be a useful biomarker to distinguish between malignant and non-malignant causes of pleural effusion. In addition, pyruvate kinase M2 has also been found to be elevated in saliva in cancer patients compared to controls. Measuring pyruvate kinase M2 in saliva may be used to diagnose cancer or monitor the treatment progress of cancer.

Inclusion Criteria:

• Any cancer patient with pleural effusion that is being drained through an indwelling chest-tube in an inpatient ward.

Exclusion Criteria:

• Patient with a pleural effusion who does not have proven cancer or whose pleural effusion is not known to be malignant.

Any cancer patient