Abstract
It has been reported that carbohydrate antigen 19-9 (CA19-9) value is low in patients with Lewis blood type Le (a–, b–). Routine Lewis blood typing, however, is not covered by health insurance in Japan. Some investigators aimed to estimate Lewis blood types with the CA19-9 value, nevertheless, their study had limits to generalizability because of various or complicated methods. We performed Lewis blood typing in 106 patients with low CA19-9 value (≦1.0 U/ml ) measured by LUMIPULSE G1200 and LUMIPULSE CA19-9 N, and analyzed change of CA19-9 with time in 593 patients with gastrointestinal cancer who underwent chronologically successive measurements of CA 19-9 until their death. The 115 (99%) out of 116 patients with low CA19-9 value (≦1.0 U/ml ) had Le (a–, b–). The minimum CA19-9 values were not greater than 1.0 U/ml in 55 (9.2%) out of the 593 patients. The maximum CA19-9 values were not greater than 37 U/ml (reference value) in 53 (96%) out of the 55 patients with the minimum CA19-9 ≦1.0 U/ml. In conclusion, patients with low CA19-9 value (≦1.0 U/ml ) usually have Le (a–, b–). Chronologically successive measurement of CA19-9 is futile in patients with CA19-9 ≦1.0 U/ml.
