Why do people with cancer tend to lose blood and where is it going?

There are several mechanisms by which people with cancer may experience blood loss:

1. Tumor Bleeding: Some cancers, such as tumors of the gastrointestinal tract (e.g., stomach or colon cancer) or lung cancer, can directly cause bleeding into the digestive tract or airways, leading to blood loss. This bleeding can occur due to the erosion of blood vessels by the tumor or the production of substances that promote blood vessel fragility.

2. Bone Marrow Suppression: Cancer treatments, such as chemotherapy and radiation therapy, can affect the bone marrow, where blood cells are produced. This can lead to a decrease in the production of red blood cells, white blood cells, and platelets, resulting in anemia (low red blood cell count) and thrombocytopenia (low platelet count). Anemia and thrombocytopenia can cause easy bruising, bleeding gums, nosebleeds, and heavy menstrual bleeding.

3. Disseminated Intravascular Coagulation (DIC): Some cancers can trigger DIC, a condition in which the blood clotting process becomes abnormal. DIC can lead to the formation of small blood clots throughout the bloodstream, consuming platelets and clotting factors. This can result in bleeding and difficulty in controlling bleeding.

4. Iron Deficiency: Certain cancers, especially those of the gastrointestinal tract, can lead to malabsorption of nutrients, such as iron. Iron deficiency can cause anemia, contributing to fatigue and weakness.

As for where the blood is going, it depends on the source of bleeding. If the bleeding is from a tumor, the blood will be lost into the digestive tract, lungs, or other affected areas. If the bleeding is due to bone marrow suppression or DIC, the blood loss occurs throughout the body, leading to symptoms such as easy bruising and bleeding.