Sometimes the first sign that a person has pancreatic cancer is a blood clot in a large vein, often in the leg. This is called deep phlebothrombosis (DVT). Symptoms can include pain, swelling, redness, and warmth in the affected leg. Sometimes a clot fragment can break off and travel to the lungs, making it difficult to breathe and causing chest pain. A blood clot in the lungs is called a pulmonary embolism (PE).
Even so, having a blood clot does not usually mean that you have cancer. Most blood clots are due to other causes.