Bleeding is a common complication for cancer patients. It can range from subtle bruising to severe internal hemorrhages. Understanding the reasons for bleeding is important for patient care. Cancer and its therapies can disrupt the body’s blood flow control system, increasing bleeding risk.
Impact on Platelet Production
The most frequent cause of bleeding in cancer patients is a reduced number of platelets, a condition known as thrombocytopenia. Platelets are small cell fragments produced in the bone marrow that play a role in forming blood clots to stop bleeding when a blood vessel is injured. They form an initial plug at injury sites and help create a stronger clot.
Many cancer treatments, particularly chemotherapy and radiation therapy, can suppress bone marrow function. This impairs the bone marrow’s ability to produce new blood cells, including platelets, leading to a decrease in their count.
Beyond treatment effects, certain cancers directly impact platelet production by infiltrating and damaging the bone marrow. Conditions like leukemia and lymphoma can crowd out normal blood cell formation. Similarly, metastatic cancer, where cancer cells spread to the bone marrow, can also impair platelet production. This direct interference with bone marrow function contributes to thrombocytopenia and bleeding.
Direct Tumor Effects
The physical presence and growth of a tumor can directly contribute to bleeding. Tumors can expand into and erode the walls of nearby blood vessels, leading to rupture and hemorrhage. This direct invasion can result in blood loss.
The blood vessels that form within tumors are often abnormal and fragile. These newly formed vessels are disorganized, leaky, and prone to rupturing. This fragility makes them susceptible to bleeding.
Bleeding due to direct tumor effects can occur in various parts of the body. The gastrointestinal tract is a common site, where tumors can cause bleeding that may present as visible blood in stool or vomit. Bleeding can also occur in the lungs, manifesting as coughing up blood, or in the urinary tract, resulting in blood in the urine.
Systemic Clotting Impairments
Beyond issues with platelet numbers, cancer patients can experience systemic problems that hinder their blood’s ability to clot effectively. The liver plays a role in producing many clotting factors, which are proteins necessary for blood coagulation. If liver function is impaired, perhaps due to cancer metastases or treatment side effects, clotting factor production can decrease, increasing bleeding risk.
Another condition that impairs clotting is Disseminated Intravascular Coagulation (DIC). In DIC, the body’s clotting system becomes inappropriately activated throughout the bloodstream, leading to widespread formation of tiny blood clots. This extensive clotting consumes platelets and clotting factors at an accelerated rate, eventually depleting them and paradoxically leading to widespread bleeding.
Severe infections, commonly referred to as sepsis, are frequent in immunocompromised cancer patients and can trigger DIC. The inflammatory response associated with sepsis can activate the clotting cascade, contributing to DIC and further impairing the body’s ability to control bleeding. This interplay of infection and coagulation dysfunction elevates bleeding risk.
Treatment-Induced Bleeding
Certain cancer therapies can directly increase the risk of bleeding, separate from their effects on bone marrow function. Some targeted therapies and immunotherapies can affect blood vessel integrity or interfere with clotting mechanisms. These treatments may cause inflammation or damage to vessel walls, making them more susceptible to bleeding.
Many cancer patients receive anticoagulant medications, often called blood thinners, to prevent blood clots, a common complication of cancer. While these medications are important for preventing dangerous clots, they inherently increase bleeding risk. The balance between preventing clots and avoiding bleeding requires careful management.
Surgical procedures, while often necessary for cancer treatment, also pose a risk for bleeding. Any surgery involves cutting into tissues and blood vessels, which can lead to acute blood loss. While typically managed during the procedure, surgical sites remain a potential source of bleeding in the immediate aftermath.