The present invention is related to a method for measuring the level of the Secreted Protein Acidic and Rich in Cysteine (SPARC) protein in a human biological sample of formalin fixed tissue, comprising detecting and quantifying the amount of a SPARC fragment peptide in a liquid, soluble, dilutable protein digest prepared from said human biological sample by heating and proteolysis, wherein said detecting and/or quantifying is carried out using mass spectrometry； and calculating the level of SPARC protein in said sample； wherein the SPARC fragment peptide is selected from the group consisting of SEQ ID NO:4, SEQ ID NO:5 and SEQ ID NO:6； wherein said level is a relative level or an absolute level； and wherein the method further comprises selecting for the subject from which said biological sample was obtained a treatment based on the presence, absence, or amount of one or more SPARC fragment peptides or the level of SPARC protein.
