Lactosylsphingosine-reactive antibody and CEA in patients with colorectal cancer

The sera of 71 patients with colorectal cancer were examined for lactosylsphingosine-reactive antibody and CEA. Fifteen of those patients were studied repeatedly over extensive periods of time. The antibody was determined by the semiquantitative radioimmunoabsorption technique using lactosylsphingosine-polyacrylamide conjugate and [125I]-labelled anti-human IgG. Excessive antibody levels were invariably found In serum samples of all 39-patients who were examined before or within 2 months after surgery. Serum samples of certain patients became negative for the presence of high antibody levels usually between 3 and 6 months after surgery. This occurred in 13 out of 41 operated patients. The follow-up study revealed that 11 such patients have been free of any signs of cancer relapse up until the time of the follow-Up examination, i.e. for 12-28 months, mean 19 months. In contrast, only 4 out of 28 patients who remained positive for the excessive antibody longer than 2 months after surgery are at present free of the disease. The high antibody levels which persist more than 6 months after surgery are almost always associated with cancer recurrences or metastases. This was true for 21 out of 22 such patients. The high levels of the antibody preceded other signs of cancer relapse, including increased concentrations of CEA in about 40% of the operated patients.