The Optical Kerr Effect was demonstrated for the first time as a new optical biopsy method to detect normal and grades of cancer of human breast tissues. The technique works by temporally tracking the various electronic and molecular processes that give rise to the nonlinear index of refraction (n2). The rate at which these processes populate and dissipate varies depending on the internal properties of the sample. It is shown here that in tissues, the variances in the ultrafast plasma Kerr responses that relates to the dielectric relaxation can be used as a biomarker for cancer. The relaxation of this response changes significantly between healthy and different grades of triple negative breast cancer tissues. This change can be attributed to a doubling or tripling of the tissue’s conductivity depending on the cancer grade.