Angiosarcoma is a rare and aggressive cancer that begins in the cells lining blood vessels or lymphatic vessels. Though it represents only a small fraction of all cancers, its impact on those diagnosed can be significant. Understanding this disease helps patients and families navigate their journey with greater clarity and confidence.

Understanding How Common Angiosarcoma Is

Angiosarcoma is extremely uncommon, affecting approximately one person per million each year in the United States. This cancer makes up only about one to two percent of all soft tissue sarcomas, which are themselves rare tumors that develop in the connective tissues of the body.^[1][4] To put this in perspective, soft tissue sarcomas account for just one percent of all cancers, making angiosarcoma a disease within an already rare category.^[1]

The disease affects people across all ages, though it is most commonly diagnosed in older adults. The typical age at diagnosis is around 70 years old, with many patients falling into the 60 to 74 age range.^[7][9] When looking at gender distribution, angiosarcoma appears to affect men and women relatively equally overall. However, certain types show patterns: more men than women develop primary angiosarcoma, while breast angiosarcoma naturally occurs more frequently in women.^[7][17]

The most frequent location for angiosarcoma is the skin, particularly on the head and neck region. About 60 percent of all angiosarcomas develop in the skin, with the scalp being especially vulnerable.^[1][5] The disease can also appear in the breast, liver, spleen, heart, bones, and deep tissues throughout the body, though these locations are less common.^[2]

What Causes This Disease

The exact cause of most angiosarcomas remains unknown to medical researchers. However, scientists have identified that the disease begins when cells in the lining of blood vessels change from normal to abnormal. Unlike healthy cells that die at the end of their life cycle, these cancerous cells continue to multiply without control, eventually forming tumors.^[7] These abnormal cells keep growing from the affected blood vessels and often spread to other areas of the body.

In some cases, angiosarcoma develops spontaneously without any clear trigger. There have been reports of the cancer transforming from previously benign vascular lesions, though this is uncommon.^[1] Recent genetic research has identified mutations in certain genes, including KDR, TP53, and PIK3CA, in some angiosarcoma tumors, suggesting that genetic changes play a role in the disease’s development.^[8]

When angiosarcoma appears in the scalp and face, particularly in the head and neck region, researchers have found evidence suggesting that ultraviolet radiation from sun exposure may be a contributing factor. This is supported by the presence of specific mutation patterns associated with UV damage in these tumors.^[8] This finding suggests that long-term sun exposure to the scalp and face might increase vulnerability to this type of cancer.

Risk Factors That Increase Your Chances

While anyone can develop angiosarcoma, certain factors significantly increase the risk. Understanding these risk factors helps identify people who may benefit from closer monitoring, though having a risk factor does not guarantee that someone will develop the disease.

Previous radiation therapy stands out as one of the most significant risk factors. People who received radiation treatment for another cancer, particularly breast cancer, face an elevated risk of developing angiosarcoma years later. This type of cancer, called radiation-induced angiosarcoma, typically appears eight to ten years after the original radiation treatment.^[7][8] Angiosarcoma commonly develops on the chest wall in breast cancer survivors who underwent radiation therapy to that area.^[1]

Chronic lymphedema, which is persistent swelling caused by a buildup of lymphatic fluid, represents another important risk factor. This swelling usually occurs in the arms or legs and can result from cancer treatment, surgery (especially lymph node removal), infection, or sometimes develops without a clear cause.^[1][7] When angiosarcoma develops in someone with long-standing lymphedema following breast cancer surgery, it is specifically called Stewart-Treves syndrome.^[1] The swelling creates an environment that may allow cancer cells to develop more easily, possibly because the lymphatic system’s ability to fight abnormal cells is compromised in swollen areas.

Exposure to certain chemicals in occupational or environmental settings has been linked to angiosarcoma, particularly when the cancer develops in the liver. Substances including vinyl chloride (used in plastics manufacturing), arsenic, thorium dioxide, and certain anabolic steroids have all been associated with increased risk.^[1][7] The latency period between exposure and disease development can be remarkably long, sometimes spanning 10 to 40 years.^[7]

Certain rare genetic conditions also elevate risk. Families with mutations in DNA repair genes, specifically BRCA1 and BRCA2, have shown associations with angiosarcoma in case reports. Additionally, inherited syndromes such as neurofibromatosis, Maffucci syndrome, and Klippel-Trenaunay syndrome carry increased risk.^[1] Some research has identified that changes in a gene called POT1 may lead to angiosarcoma of the heart, and this genetic alteration can be passed from parent to child.^[4]

Recognizing the Symptoms

The symptoms of angiosarcoma vary widely depending on where in the body the cancer develops. Because this disease can appear almost anywhere, the warning signs differ significantly from person to person.

When angiosarcoma develops on the skin, particularly on the head, neck, or scalp, it often appears as an area that looks like a bruise but behaves differently from normal bruises. This discolored patch may be reddish, blue, or purple and does not fade away as a typical bruise would.^[2][7] Instead, it tends to grow larger over time. The affected area may develop raised small lumps that eventually spread and bleed easily when scratched or bumped.^[7] Some patients notice a sore that refuses to heal or seems to be growing instead of closing.^[7] The skin around the affected area may begin to swell.^[2]

Pain and tenderness can develop in the affected area, though not all patients experience discomfort. Some skin angiosarcomas do not hurt at all and are noticed primarily because of their unusual appearance.^[7] The rapidly growing nature of the lump or bump often prompts people to seek medical attention.

When angiosarcoma develops inside the body, in organs such as the liver, spleen, or heart, symptoms may not appear until the tumor grows large enough to interfere with how the organ functions or creates pressure on surrounding structures.^[7] Patients might experience persistent pain near the affected organ. For instance, angiosarcoma in the liver can cause pain in the upper abdomen along with jaundice, which is a yellowing of the skin and eyes.^[7] When the tumor affects the heart, shortness of breath is the most common symptom.^[7]

General symptoms that can accompany angiosarcoma in various locations include unexplained fatigue, malaise (a general feeling of being unwell), and unintentional weight loss.^[7] In some patients, fluid buildup or swelling develops in the area where the tumor is growing.^[2] Because angiosarcoma often spreads to other parts of the body, symptoms related to these secondary sites may also appear, such as lung-related symptoms if the cancer has spread to the lungs.

Prevention Strategies

Because the exact cause of most angiosarcomas remains unknown, preventing the disease entirely is not always possible. However, certain strategies may help reduce risk based on what researchers have learned about contributing factors.

For individuals who have undergone radiation therapy, awareness and vigilance become important preventive tools. While radiation-induced angiosarcoma is rare, people who received radiation treatment should remain alert to changes in the treated area, particularly changes in skin appearance or new lumps that develop years after treatment. Regular follow-up appointments with healthcare providers allow for monitoring of the previously treated area.^[8] Early detection of any changes enables prompt investigation and diagnosis if cancer develops.

Managing chronic lymphedema effectively may help reduce risk for those who have this condition. Proper care includes compression garments, exercises recommended by physical therapists, skin care to prevent infection, and positioning techniques to reduce swelling. While these measures primarily aim to improve quality of life and reduce complications of lymphedema itself, maintaining the healthiest possible tissue environment may offer some protective benefit.

For angiosarcoma that may be related to UV exposure on the scalp and face, sun protection measures seem prudent. Using hats that provide coverage to the scalp, applying sunscreen to exposed areas of the scalp (particularly for those with thinning hair or bald spots), and limiting peak sun exposure may theoretically reduce risk, though this has not been definitively proven.^[8]

In occupational settings where exposure to known carcinogenic chemicals occurs, following safety protocols and using appropriate protective equipment is essential. Workers in industries involving vinyl chloride, arsenic, or other associated chemicals should adhere to workplace safety standards designed to minimize exposure.^[7]

For individuals with genetic conditions that increase angiosarcoma risk, genetic counseling can provide valuable information about screening strategies and what symptoms to watch for. While having a genetic predisposition cannot be changed, awareness allows for earlier detection if cancer develops.

How Angiosarcoma Changes Normal Body Function

To understand the pathophysiology of angiosarcoma, it helps to know what happens in the body when this cancer develops. The disease originates in endothelial cells, which are the cells that form the inner lining of blood vessels and lymphatic vessels throughout the body.^[1] These cells normally create a smooth barrier between the bloodstream or lymphatic fluid and the surrounding tissues.

When angiosarcoma begins, the endothelial cells undergo changes that transform them from normal, well-behaved cells into malignant cancer cells. This transformation involves genetic mutations that alter how the cells function. The cancerous cells lose their normal regulatory controls, particularly the mechanisms that usually signal when cells should stop dividing and when damaged cells should die.^[7]

As these abnormal cells multiply, they form new, irregular blood vessels in a chaotic pattern rather than the organized vessel structure found in healthy tissue. These newly formed vessels are abnormal in structure and function. The tumor creates its own blood supply through a process called angiogenesis, where new blood vessels sprout to feed the growing cancer.^[2] This is why angiosarcomas are typically very vascular tumors, meaning they have extensive blood vessel involvement and may bleed easily.

Angiosarcoma is classified as “high-grade” by definition, meaning the cancer cells appear very abnormal under the microscope and behave aggressively.^[1] High-grade tumors tend to grow rapidly and spread quickly to other parts of the body. The tumor infiltrates surrounding tissues extensively, growing into and between normal structures rather than remaining as a contained mass. This infiltrative growth pattern makes complete surgical removal challenging because microscopic cancer cells may extend beyond what can be seen or felt.

The cancer has a strong tendency to metastasize, which means cancer cells break away from the original tumor and travel through the bloodstream or lymphatic system to form new tumors in distant parts of the body. The lungs are a particularly common site for angiosarcoma to spread, but the cancer can also metastasize to the liver, bones, and other organs.^[5] Studies show that between 16 and 44 percent of patients already have advanced or metastatic disease by the time they are first diagnosed.^[5]

In angiosarcomas that develop following radiation therapy, the cancer typically appears in the previously irradiated field. The radiation damage to DNA in the endothelial cells, which occurred years earlier during cancer treatment, eventually leads to the malignant transformation of these cells. Similarly, in cases associated with chronic lymphedema, the theory suggests that the abnormal fluid environment and impaired immune surveillance in the swollen area create conditions that allow cancer cells to develop and grow unchecked.

When angiosarcoma affects specific organs, it disrupts their normal function in particular ways. For example, angiosarcoma in the liver can interfere with the organ’s ability to filter blood, produce proteins, and process nutrients. In the heart, tumors can block blood flow through heart chambers, disrupt the heart’s electrical signals, or prevent valves from working properly. On the skin, the tumor breaks down the normal skin barrier, leading to open wounds that bleed and become vulnerable to infection.

The aggressiveness of angiosarcoma also relates to the tumor’s microenvironment. Because these cancers originate from blood vessel cells, they have inherent access to the body’s circulatory system, which may facilitate their ability to spread. The extensive network of irregular blood vessels within the tumor creates areas of abnormal blood flow, sometimes leading to pooling of blood within the tumor itself, which can cause the bruise-like appearance seen in skin lesions.