1）便潜血反応─Hb・Tf同時測定法

Early Colorectal Cancer Screening─an Immunochemical Fecal Occult Blood Test Using Hb / Tf Simultaneous Assay

要旨　全大腸内視鏡検査施行の病院受診者1,149例を対象に，Hb・Tf同時測定法とHb単独測定法〔Hb（＋）法〕，Tf単独測定法〔Tf（＋）法〕との大腸癌スクリーニング精度を比較検討した．Tf（＋）法はHb（＋）法に比して特異度では上回っていたが，感度においては及ばなかった．Hb・Tf同時測定・組み合せ判定法では，Hb（＋）法に比して，HbかTfのいずれか陽性を反応陽性とする判定法〔Hb（＋）or Tf（＋）法〕で感度が上昇するが，特異度や陽性的中率は低下した．また，HbとTfのいずれも陽性を反応陽性とする判定法〔Hb（＋）and Tf（＋）法〕で特異度と陽性的中率の上昇を認めたが，感度は低下した．Hb・Tf同時測定・2段階判定法では，パターンAはHb（＋）法の感度を維持したまま特異度を上げ，パターンBではHb（＋）法の特異度を維持しながら感度を上げるため， Hb（＋）法よりも精度の高い検査になる可能性が示された．

　In 1,149 outpatients who underwent total colonoscopy, we weighed colorectal cancer screening precision with assay of Hb alone〔Hb（＋）method〕against the Hb/Tf simultaneous assay. The Tf alone assay〔Tf（＋）method〕exceeded in specificity the Hb（＋）method, but was inferior in sensitivity. Using the method of Hb/Tf simultaneous assay with combination judgment, the Hb（＋）or Tf（＋）method produced an elevation of the sensitivity above that of the Hb（＋）method, but the specificity and the positive prediction value rate decreased. Also, the Hb（＋）and Tf（＋）method showed an elevation of specificity and positive prediction value, but its sensitivity decreased. Using Hb/Tf simultaneous assay with the two-step steps judgment method, pattern A retains the sensitivity of the Hb（＋）method and gives an elevation of specificity, and pattern B gives an elevation of sensitivity while maintaining the specificity of the Hb（＋）method. As a result, it is indicated that the Hb/Tf simultaneous assay with the two-step judgment method is potentially a more highly-accurate method for the screening of colorectal cancer than the Hb（＋）method.