Prognostic importance of the soluble plasminogen activator receptor; suPAR, in plasma from rectal cancer patients

Colorectal cancer is one of the most common tumour types with approximately one third of the tumours located within the rectum. Rectal cancer differs somewhat from colon cancer, e.g. regarding the method of operation and the use of preoperative radiotherapy due to a tendency for local tumour recurre nce. Proteolytic enzymes have been identified as key molecules in tumour in vasion and metastasis, and factors within the urokinase-plasminogen activat ion (uPA) system have been associated with prognosis in several tumour type s, including colorectal cancer. Recently, methods have been developed to an alyse the soluble fraction of the plasminogen activator receptor (suPAR) in blood samples. An association between elevated suPAR levels and poor progn osis has recently been demonstrated in colorectal cancer. We have measured suPAR levels in pretreatment plasma samples from 173 rectal cancer patients in order to confirm its prognostic strength in this clinical entity. suPAR levels were determined in ethylenediamine tetraacetic acid (EDTA) plasma b y a kinetic enzyme-linked immunosorbent assay (ELISA) and analysed with res pect to sex, age, Dukes' stage, tumour differentiation grade and survival. In a univariate analysis, continuous suPAR plasma levels were associated wi th survival (P<0.001) with shorter survival among patients with high suPAR values. Patients with suPAR values within the upper quartile had significan tly shorter survival (hazard ratio (HR) 2.2, 95% confidence interval (CI) 1 .3-43.7, P=0.002). In a multivariate Cox analysis, increasing suPAR values predicted shorter survival independent from Dukes' stage and tumour differe ntiation grade with an adjusted HR of 2.2 per ng/ml suPAR (95% CI 1.2-4.0, P=0.01). This study thus confirms that measurement of suPAR in preoperative plasma samples gives independent prognostic information in rectal cancer p atients, higher values being associated with shorter survival. <(c)> 2001 E lsevier Science Ltd. All rights reserved.