Abstract: A sugar chain analysis method is a method for analyzing a sugar chain structure bound to an antibody, the method including: a releasing step of adding a sugar cleavage enzyme to a sample containing an antibody, so that a sugar chain bound to the antibody is specifically released to obtain a free sugar chain; a recovery step of recovering the free sugar chain by affinity purification; a hydrophobization step of hydrophobizing the free sugar chain to obtain a hydrophobized sugar chain; and a measurement step of performing supercritical liquid chromatography and tandem mass spectrometry in this order on the hydrophobized sugar chain.

Abstract: Provided is a test method for identifying prostate cancer by analyzing a sugar chain modifying PSA in a specimen, and detecting an abundance of a multisialylated LacdiNAc structure, in particular Glycan ID: 7512, Glycan ID: 7603, Glycan ID: 7612, and/or Glycan ID: 7613. Furthermore, calculation of PSA G-index from relative abundance(s) of Glycan ID: 7512 and/or Glycan ID: 7603 enables detection of prostate cancer with good specificity even in a patient having a PSA value in a gray zone.