Blood vessel entwined with a cancerous growth

Cancer and Blood Clots: What You Need to Know About Thrombosis and Bleeding

Nico Varela in Health & Wellness July 2025 • 3 min read.

"Understanding the delicate balance between thrombosis and bleeding in cancer patients can improve overall health and treatment outcomes."

For over a century, medical professionals have recognized the connection between cancer and hypercoagulability – an increased tendency to form blood clots. Armand Trousseau first described the association in the 19th century. Cancer patients often experience an imbalance, predisposing them to both thrombosis (clotting) and bleeding.

While the presence of malignant cells contributes to coagulation, it’s now understood that the process is far more complex. The type of cancer, its stage, and treatments all play a role, making personalized understanding critical. Specific genetic alterations, especially in hematological malignancies, can further heighten thrombotic risks.

Navigating these complexities requires a comprehensive approach. This article reviews current insights into thrombosis and bleeding in cancer patients, offering practical information to help understand, manage, and mitigate these risks.

Why Are Cancer Patients More Prone to Blood Clots?

Blood vessel entwined with a cancerous growth

Cancer triggers significant changes in the body's coagulation processes. Biochemical markers consistently show increased activity in both plasma and platelets, indicating a procoagulant state. This includes elevated levels of prothrombin fragments, thrombin-antithrombin complexes, and increased fibrin generation and degradation, reflected in elevated D-dimer levels.

These coagulation markers highlight a procoagulant phenotype, but they don't directly predict individual thromboembolic events. Instead, they reflect an overall increased risk associated with higher marker concentrations. Studies confirm a high prevalence of clinically silent thrombi in cancer patients, often discovered during autopsies.

Tumor interactions: Cancer cells directly interact with the coagulation system, promoting clot formation.
Inflammation: Cancer-related inflammation activates clotting pathways.
Immobility: Reduced physical activity during cancer treatment increases the risk of blood clots.
Treatment effects: Chemotherapy and other treatments can damage blood vessels and further stimulate clotting.

Cancer-associated venous thromboembolism (VTE) can sometimes precede a cancer diagnosis, especially in acute myelogenous leukemia (AML), non-Hodgkin lymphoma (NHL), and renal, ovarian, and pancreatic cancers. Diagnosing VTE can serve as an early indicator, prompting investigations that uncover previously undetected malignancies.

Striking the Balance: Managing Coagulation in Cancer Care

Managing coagulation in cancer patients requires a delicate balance, mindful of both thrombotic and bleeding risks. Awareness of VTE's high frequency and mortality in cancer underscores the importance of proactive strategies. While low-molecular-weight heparin (LMWH) has been a mainstay for VTE prevention and treatment, recent studies and evolving guidelines suggest a shifting landscape. Direct oral anticoagulants (DOACs) are emerging as valuable options, offering potential benefits in efficacy and convenience.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1007/978-3-319-90990-5_19, Alternate LINK

Title: Thrombosis And Bleeding In Cancer Patients

Journal: The MASCC Textbook of Cancer Supportive Care and Survivorship

Publisher: Springer International Publishing

Authors: Wolfgang Korte

Published: 2018-01-01

Everything You Need To Know

What bodily changes occur in cancer patients that make them more susceptible to blood clots?

Cancer triggers changes that promote increased clotting. The body's coagulation processes become more active, which includes increases in prothrombin fragments, thrombin-antithrombin complexes, and elevated D-dimer levels. These coagulation markers highlight an overall increased risk of blood clot formation. Cancer cells, inflammation, immobility, and treatments like chemotherapy all contribute to this increased risk.

What are the current strategies for managing coagulation issues in cancer patients, and how have they evolved?

Low-molecular-weight heparin (LMWH) has traditionally been the primary method for preventing and treating VTE in cancer patients. However, direct oral anticoagulants (DOACs) are becoming more popular due to their potential benefits in terms of effectiveness and ease of use. The choice between LMWH and DOACs depends on individual patient factors and evolving guidelines.

Who first identified the link between cancer and blood clotting, and when was this connection established?

Armand Trousseau was the first to describe the association between cancer and hypercoagulability in the 19th century. He observed that cancer patients had an increased tendency to form blood clots, marking the beginning of research into the complex relationship between cancer and coagulation.

Can blood clots serve as an early warning sign for cancer, and if so, what types of cancer are most associated with this?

Cancer-associated venous thromboembolism (VTE) can sometimes be an early sign of cancer, especially in cases like acute myelogenous leukemia (AML), non-Hodgkin lymphoma (NHL), and renal, ovarian, and pancreatic cancers. When VTE is diagnosed without a known cause, it may prompt further investigation to detect any underlying, previously undetected malignancies.

What specific factors related to cancer contribute to the increased risk of blood clots in patients?

Malignant cells interact with the coagulation system, inflammation activates clotting pathways, immobility during cancer treatment increases risks, and certain treatments like chemotherapy can damage blood vessels and further stimulate clotting. The interplay of these factors contributes to the increased risk of blood clots in cancer patients.