Method for determining the response to cancer therapy

A method for determining a response to administration of a chemotherapeutic or chemopreventive agent to an individual, comprising:

• (a) collecting a first tissue or cell sample from the individual before exposing the individual to the chemotherapeutic or chemopreventive agent;
• (b) collecting a second tissue or cell sample from the individual after exposing the individual to the chemotherapeutic or chemopreventive agent;
• (c) immunohistochemically staining the first and second tissue or cell samples using a detectably-labeled antibody directed against a biological marker associated with senescence, apoptosis or terminal differentiation;
• (d) measuring the optical density of the stained cells as in step (c), wherein the stained cells are illuminated with light having a wavelength absorbed by the stain;
• (e) determining whether expression of the biological marker associated with senescence, apoptosis or terminal differentiation was increased following exposure to the chemotherapeutic or chemopreventive agent.