Protein C activity, stage of disease, and vascular thrombosis in colon carcinoma.

To determine the etiology of the increased incidence of postoperative deep venous thrombosis (DVT) in patients with carcinoma of the colon, serum levels of protein C were measured preoperatively in 65 patients with colorectal adenocarcinoma. Noninvasive lower-extremity Doppler studies were performed on all patients prior to discharge to assess patency of the deep veins. Six patients (9%) were found to have DVT. The protein C level was considered elevated if it was greater than 125% of control values and reduced if less than 75% of control values. The development of DVT was found to be independent of the serum carcinoembryonic antigen, albumin, total protein, hemoglobin, hematocrit, platelet count, prothrombin time, partial thromboplastin time, and the patient's age and percentage of ideal body weight. There was an inverse relationship between the protein C level (p less than 0.001), Dukes stage of the tumor (p less than 0.001), and the development of DVT. Linear regression analysis revealed that only the tumor stage and the protein C level could be used to predict the development of DVT. The data show that for these patients with colorectal malignancy, the development of DVT may be related to decreased levels of protein C.