The invention relates to an ultra-low molecular weight heparin with an average molecular weight of 2000 to 3000 Daltons, an anti-FXa activity of about 160 U/mg and an anti-FIIa activity of about 2 U/mg, in particular semuloparin, for use as an antithrombotic agent for the prophylaxis of venous thromboembolism in cancer patients receiving chemotherapy for locally advanced or metastatic solid tumors, more specifically in patients receiving chemotherapy for locally advanced or metastatic pancreatic or lung cancer, or for locally advanced or metastatic solid tumors with a VTE risk score equal to or greater than 3.
