CyPath® Lung testing is performed on sputum processed into a single-cell suspension labeled with the fluorescent porphyrin TCPP that preferentially binds to cancer cells and cancer-related cells. Cells are also stained with fluorescently labeled antibodies that identify hematopoietic and epithelial cells within the sputum sample. A viability dye is used to eliminate dead cells. After the sputum sample is run through the flow cytometer and the sample data is acquired, software searches for the presence of pre-defined features that distinguish individuals at high risk who have a high likelihood of lung cancer from those who do not.