Epithelioid hemangioendothelioma (EHE) is not considered curable in most cases, but it is a slow-growing cancer that many people live with for years. The five-year overall survival rate is roughly 56%, though outcomes vary widely depending on the genetic subtype, where the tumor is located, and whether it has spread. Some patients with localized disease can be effectively treated with surgery, and a small number with liver-only EHE have achieved long-term remission after organ transplant.
What EHE Is and Why It’s Hard to Classify
EHE is a rare vascular tumor, meaning it grows from the cells that line blood vessels. Only about one in every million people worldwide is diagnosed with it each year. It sits in an unusual middle ground: not as harmless as a benign blood vessel growth and not as aggressive as angiosarcoma, the most dangerous type of vascular cancer. Doctors classify it as an intermediate or borderline malignant tumor, which partly explains why its behavior is so unpredictable. Some tumors barely change for years, while others spread aggressively.
EHE can develop almost anywhere in the body but most commonly appears in the liver, lungs, and bones. It is frequently discovered by accident on a CT or MRI scan done for an unrelated reason. When symptoms do appear, they tend to be vague: pain near the tumor site, unexplained weight loss, fatigue, or swelling from a blocked vein. Unexplained anemia shows up in multiple patients. Because the cancer is so rare and the symptoms so nonspecific, diagnosis is often delayed.
Two Genetic Subtypes With Different Outlooks
Nearly all EHE tumors are driven by one of two gene fusions, abnormal joins between two genes that force cells to grow uncontrollably. The subtype matters because it directly affects prognosis.
- WWTR1::CAMTA1 fusion (about 95% of cases): This is the more common and more concerning subtype. Five-year survival ranges from 50% to 80%.
- YAP1::TFE3 fusion (about 5% of cases): This rarer subtype tends to behave less aggressively. Five-year survival is estimated at 86% to 88%.
Both fusions work through a similar mechanism. They produce abnormal proteins that get stuck in the “on” position inside the cell nucleus, constantly signaling the cell to grow and divide. Understanding this shared biology has helped researchers identify potential drug targets, though no therapy specifically designed around these fusions is available yet.
Survival by the Numbers
Data from the U.S. SEER cancer registry puts the overall one-year survival rate at about 71%, dropping to 61% at three years and 56% at five years. These numbers represent all patients across all stages and subtypes, so they include both the most favorable and most aggressive cases. Your individual outlook could be significantly better or worse depending on a few key factors.
Patients who develop fluid buildup around the lungs or abdomen (serosal effusion) or who have widespread systemic symptoms tend to do considerably worse. In one analysis of drug-treated patients, those with serosal involvement had a median time before their cancer worsened of less than five months, compared to nearly four years for those without it. Tumor location, the specific genetic subtype, and whether the cancer has already spread at diagnosis all shape the trajectory as well.
Surgery and Liver Transplant
For EHE that is confined to a single area, surgical removal offers the best chance at long-term control and, in some cases, what functionally looks like a cure. Patients with a single liver tumor or a small number of bone or soft tissue lesions may have their tumors completely resected, and some remain disease-free for years afterward.
Liver transplant is a unique option for EHE that is limited to the liver but too widespread within the organ to cut out. Because the liver is the most common site for EHE and the tumors often appear as multiple nodules scattered throughout both lobes, transplant comes up more frequently for this cancer than for most sarcomas. Reported long-term survival after transplant for hepatic EHE is favorable compared to transplant for other liver cancers, though recurrence remains a risk. The decision hinges on confirming that the disease has not spread beyond the liver.
Drug Treatments for Advanced EHE
When EHE has spread too widely for surgery, several systemic therapies can slow progression, though none reliably shrink or eliminate the cancer. The goal shifts from cure to disease control, keeping the tumor stable for as long as possible.
Pazopanib, a drug that blocks blood vessel growth, is one of the more studied options. In a recent analysis of 13 patients who received it as a first treatment, the median time before the cancer progressed was 35 months, and 62% of patients achieved stable disease lasting at least six months. Notably, no patients saw their tumors shrink significantly by standard measurement criteria, but prolonged stability is considered a meaningful win in a cancer this slow-growing. For patients whose tumors were already growing before treatment started, median progression-free survival was about 13 months.
Sirolimus, a drug that suppresses a growth-signaling pathway inside cells, has also shown modest activity. In a study of 38 patients, median progression-free survival was 13 months, and about 11% had measurable tumor shrinkage. Its effectiveness dropped sharply in patients with fluid buildup around organs, where median progression-free survival fell to under five months.
Sorafenib, another blood-vessel-targeting drug, has produced partial responses in a small number of patients but with a shorter median progression-free survival of about six months. A Phase II trial is also testing eribulin, a drug originally derived from a sea sponge compound that kills cancer cells by disrupting their ability to divide.
What “Watch and Wait” Looks Like
Because EHE can remain stable for months or even years without treatment, not every patient starts therapy immediately after diagnosis. Doctors sometimes recommend active surveillance: regular imaging scans to track whether the tumors are growing, changing, or staying the same. This is especially common when the tumors are small, not causing symptoms, and scattered in a way that makes surgery impractical.
The challenge with this approach is uncertainty. Some patients stay stable for a decade. Others experience sudden progression, particularly if fluid begins collecting around the lungs or in the abdomen. There is no reliable test yet to predict which trajectory a given patient will follow, which makes close monitoring essential. Imaging intervals are typically every few months early on, then may be spaced out if the disease remains quiet.
Why Outcomes Vary So Widely
Few cancers have as wide a range of possible outcomes as EHE. A person with a single, surgically removable tumor and the less aggressive genetic subtype may live a normal lifespan. Someone diagnosed with widespread disease, serosal involvement, and the more common genetic subtype faces a much harder road. The five-year survival rate of 56% is a population average that blends these very different realities together.
The rarity of EHE compounds the problem. With only one case per million people per year, clinical trials are small, treatment guidelines are based on limited data, and many oncologists will see only a handful of cases in their entire career. Seeking care at a sarcoma specialty center, where teams have accumulated more experience with vascular tumors, can make a meaningful difference in both diagnosis accuracy and treatment planning.