Disclosed is a method for monitoring early treatment response of a cancer
treatment comprising measuring by magnetic resonance spectroscopy (MRS),
for example, proton MRS, the amount of Choline present in the cancerous
tissue before and after treatment; the treatment comprises administration
of a cell surface receptor inhibitor, for example, an EGFR inhibitor,
whereby a decrease in the amount of Choline after treatment is indicative
of a positive response. The decrease in the amount of Choline represents
the decrease in the internal cell membrane as a result of down regulation
of the organelles and their secretory granules and their transport
vesicles. Disclosed also is a method for determining effectiveness of a
cell surface receptor inhibitor in the treatment of cancer.