Cancer is a very complex disease, involving multiple molecular and cellular processes arising from a gradual accumulation of genetic changes in individual cells. The most apparent morphological change is visible during the transition from a benign tumor to metastatic tumors where cells alter from highly differentiated normal phenotypes to migratory and invasive ones. Around 90% of all cancer deaths are due to metastatic spread of primary tumors. The criteria utilized to detect cancerous cells have been mainly relying on biological and morphological description, additionally complemented by a variety of other techniques, including genetic, chemical, and immunological methods, applied in order to fine-tune diagnosis or therapy. Despite enormous efforts to develop better treatment protocols, our ability to cure solid tumors, such as those of the breast, prostate, cervix or colon, is still lacking sufficient detection methods.