In this work, Raman microspectroscopy and imaging was employed to analyze cancer patients’ hair tissue. The comparison between the hair from rectum cancer patients and the hair from healthy people reveals some remarkable differences, such as for the rectum cancer patients, there are more lipids but less content of α-helix proteins in the hair medulla section. Though more statistic data are required to establish universary rules for practical and accurate diagnosis, this work based on case study demonstrates the possibility of applying Raman microspectroscopy to reveal abnormality in non-cancer tissues such as hair in order to predict and diagnose cancers