Colon cancer is one of the most reasons for cancer death worldwide. Thus, it is important to find new prognostic and diagnostic marker, as well as to throw light on the special metabolic pathways of colon cancer cells. This paper highlights for the first time some qualitative differences in the profiles of the volatile metabolites of colon cancer cell lines SW 480 (grade IV, Duke B) and SW 1116 (grade II, Duke A) among themselves and in comparison to the normal colon cell line NCM460, which are mostly represented by ketones and alcohols. These results, which were obtained by applying solid phase micro extraction (SPME) and combined gas chromatography/mass spectrometry (GC/MS), are consistent with Warburg's hypothesis because the found reaction products may indicate that the cancer cells show the Crabtree's effect. Furthermore, compounds like undecan-2-ol and pentadecan-2-one were associated for the first time with the human metabolism. In summary, these findings indicate that the metabolism of colon cancer cells differs extremely from the metabolism of healthy cells and it changes during the progress of the disease. Compounds that are present in the breath, the blood and the tissue of patients represent the differences and they can serve as new biomarker for colon cancer in future.