Association between protein C levels and mortality in patients with advanced prostate, lung and pancreatic cancer

Procoagulant factors promote cancer progression and metastasis. Protein C is involved in hemostasis, inflammation and signal transduction, and has a protective effect on the endothelial barrier. In mice, administration of activated protein C reduced experimental metastasis. We assessed the association between protein C and mortality in patients with three types of cancer.

The study population consisted of patients with advanced prostate, non-small cell lung or pancreatic cancer, who participated in the INPACT trial (NCT00312013). The trial evaluated the addition of nadroparin to chemotherapy in patients with advanced malignancy. Patients were divided into tertiles based on protein C at baseline. The association between protein C levels and mortality was evaluated with Cox proportional hazard models.

We analysed 477 patients (protein C tertiles: <97, 97-121 and ≥121%). Mean age was 65±9years; 390 (82%) were male; 191 patients (40%) had prostate cancer, 161 (34%) had lung cancer, and 125 (26%) pancreatic cancer. During a median follow-up of 10.4months, 291 patients (61%) died. Median protein C level was 107% (IQR 92-129). In the lowest tertile, 75 patients per 100 patient-years died, as compared to 60 and 54 in the middle and high tertile, respectively. Lower levels of protein C were associated with increased mortality (in tertiles: HR for trend 1.18, 95%CI 1.02-1.36, adjusted for age, sex and nadroparin use; as a continuous variable: HR 1.004, 95%CI 1.00-1.008, p=0.07).

Protein C seems inversely associated with mortality in patients with advanced prostate, lung and pancreatic cancer. Further research should validate protein C as a biomarker for mortality, and explore the effects of protein C on progression of cancer.