A method of detecting or diagnosing pancreatic cancer comprising: a) performing an organic phase extraction on a blood, serum or plasma sample to remove an inhibitor of immunoassay, wherein the inhibitor is an inhibitor of PAM4 antibody and wherein said inhibitor binds to the PAM4 antigen; and b) performing an immunoassay with an anti-pancreatic cancer antibody or pancreas cancer antigen-binding fragment thereof to detect the presence of a pancreatic cancer mucin in the sample, wherein the anti-pancreatic cancer antibody or pancreas cancer antigen-binding fragment thereof binds to a linear peptide comprising the amino acid sequence WTWNITKAYPLP (SEQ ID NO:7) or to a cyclic peptide comprising the amino acid sequence ACPEWWGTTC (SEQ ID NO:8) and wherein the anti-pancreatic cancer antibody or pancreas cancer antigen-binding fragment thereof comprises the light chain variable region CDR sequences CDR1 (SASSSVSSSYLY, SEQ ID NO: 1); CDR2 (STSNLAS, SEQ ID NO:2); and CDR3 (HQWNRYPYT, SEQ ID NO:3); and the heavy chain variable region CDR sequences CDR1 (SYVLH, SEQ ID NO:4); CDR2 (YIPYNDGTQYNEKFKG, SEQ ID NO:5) and CDR3 (GFGGSYGFAY, SEQ ID NO:6), and the anti-pancreatic cancer antibody or pancreas cancer antigen-binding fragment thereof binds to the same epitope as a chimeric PAM4 (cPAM4) antibody that comprises the light chain variable region CDR sequences CDR1 (SASSSVSSSYLY, SEQ ID NO: 1); CDR2 (STSNLAS, SEQ ID NO:2); and CDR3 (HQWNRYPYT, SEQ ID NO:3); and the heavy chain variable region CDR sequences CDR1 (SYVLH, SEQ ID NO:4); CDR2 (YINPYNDGTQYNEKFG, SEQ ID NO:5) and CDR3 (GFGGSYGFAY, SEQ ID NO:6), or the anti-pancreatic cancer antibody or pancreas cancer antigen-binding fragment thereof competes for binding to pancreatic cancer mucin with a chimeric PAM4 (cPAM4) antibody that comprises the light chain variable region CDR sequences CDR1 (SASSSVSSSYLY, SEQ ID NO: 1); CDR2 (STSNLAS, SEQ ID NO:2); and CDR3 (HQWNRYPYT, SEQ ID NO:3); and the heavy chain variable region CDR sequences CDR1 (SYVLH, SEQ ID NO:4); CDR2 (YINPYNDGTQYNEKFG, SEQ ID NO:5) and CDR3 (GFGGSYGFAY, SEQ ID NO:6); wherein the presence of the pancreatic cancer mucin is indicative of pancreatic cancer in the individual and wherein said pancreatic cancer includes stage 1A, stage 1B and stage 2 pancreatic cancer. a) performing an organic phase extraction on a blood, serum or plasma sample to remove an inhibitor of immunoassay, wherein the inhibitor is an inhibitor of PAM4 antibody and wherein said inhibitor binds to the PAM4 antigen; and b) performing an immunoassay with an anti-pancreatic cancer antibody or pancreas cancer antigen-binding fragment thereof to detect the presence of a pancreatic cancer mucin in the sample, wherein the anti-pancreatic cancer antibody or pancreas cancer antigen-binding fragment thereof binds to a linear peptide comprising the amino acid sequence WTWNITKAYPLP (SEQ ID NO:7) or to a cyclic peptide comprising the amino acid sequence ACPEWWGTTC (SEQ ID NO:8) and wherein the anti-pancreatic cancer antibody or pancreas cancer antigen-binding fragment thereof comprises the light chain variable region CDR sequences CDR1 (SASSSVSSSYLY, SEQ ID NO: 1); CDR2 (STSNLAS, SEQ ID NO:2); and CDR3 (HQWNRYPYT, SEQ ID NO:3); and the heavy chain variable region CDR sequences CDR1 (SYVLH, SEQ ID NO:4); CDR2 (YIPYNDGTQYNEKFKG, SEQ ID NO:5) and CDR3 (GFGGSYGFAY, SEQ ID NO:6), and the anti-pancreatic cancer antibody or pancreas cancer antigen-binding fragment thereof binds to the same epitope as a chimeric PAM4 (cPAM4) antibody that comprises the light chain variable region CDR sequences CDR1 (SASSSVSSSYLY, SEQ ID NO: 1); CDR2 (STSNLAS, SEQ ID NO:2); and CDR3 (HQWNRYPYT, SEQ ID NO:3); and the heavy chain variable region CDR sequences CDR1 (SYVLH, SEQ ID NO:4); CDR2 (YINPYNDGTQYNEKFG, SEQ ID NO:5) and CDR3 (GFGGSYGFAY, SEQ ID NO:6), or the anti-pancreatic cancer antibody or pancreas cancer antigen-binding fragment thereof competes for binding to pancreatic cancer mucin with a chimeric PAM4 (cPAM4) antibody that comprises the light chain variable region CDR sequences CDR1 (SASSSVSSSYLY, SEQ ID NO: 1); CDR2 (STSNLAS, SEQ ID NO:2); and CDR3 (HQWNRYPYT, SEQ ID NO:3); and the heavy chain variable region CDR sequences CDR1 (SYVLH, SEQ ID NO:4); CDR2 (YINPYNDGTQYNEKFG, SEQ ID NO:5) and CDR3 (GFGGSYGFAY, SEQ ID NO:6);