[Dextran-induced anaphylactoid reactions in two patients with gastrointestinal cancer].

We report dextran-induced anaphylactoid reactions (DIAR) subsequent to rapid infusion of Rheomacrodex (dextran 40) in two patients, a 67 year old man with gastric cancer undergoing distal gastrectomy and a 47 year old man with transverse colon cancer undergoing colectomy. Both showed sudden tachycardia, hypotension and skin flush, which were treated with epinephrine or etilephrine administration. Most cases of severe DIAR are immune complex anaphylaxis mediated by dextran-reactive antibodies (DRA) of the IgG class, which are considered to arise mainly in response to immunization with dextran-cross-reactive bacterial polysaccharides in the gastrointestinal tract. High titers of DRA have previously been reported in gastric ulcer patients with pyloric stenosis, suggesting bacterial polysaccharides permeation through the luminal wall which may easily occur in the presence of local inflammation or ulcer. Although serum DRA titers in our patients have not been examined, inflammation or ulcer around the tumor might have played a role in producing high titers of DRA. In patients suspected of gastrointestinal ulcer or inflammation, including cancer, dextran administration is not preferable or should be avoided, unless hapten-dextran preparation is used for the prophylaxis of severe DIAR.