Cancer begins with out-of-control growth of abnormal cells. What kicks off this process in primary angiosarcoma of the breast is not clear and risk factors are largely unknown.

Angiosarcoma can sometimes run in families. Some research suggests a possible genetic predisposition to develop this type of cancer, but more studies are needed in this area. Exposure to cancer-causing chemicals may also play a role in angiosarcoma.

Primary angiosarcoma of the breast is most likelyTrusted Source to affect a young woman with dense breasts and no history of breast cancer. The median age at onset is 40 years. There is no known trigger.

Secondary angiosarcoma of the breast is caused by previous radiation treatment or chronic lymphedema due to breast cancer. It has a median onset age of 70 years, and generally happens about 10.5 years after radiation therapy.

A screening mammogram may pick up on a mass you didn’t know was there. But primary angiosarcoma of the breast tends to occur in younger women who may not have started routine breast cancer screening mammograms.

If you have a breast lump or other signs of breast cancer, your doctor will likely perform a clinical exam, followed by a diagnostic mammogram. Other imaging tests may include:

• breast ultrasound
• breast MRI
• PET scan

While imaging tests can identify the general size and location of a mass, it’s not enough to make a diagnosis. Breast angiosarcomas have a nonspecific pathological pattern. They can appear much like benign lesions on imaging scans, particularly when it involves younger people with dense breasts.

The only way to accurately diagnose breast angiosarcoma is with a breast biopsy. Some research suggests that fine-needle biopsy leads to 40%Trusted Source of false negative results, so your doctor may recommend a core needle biopsy.

Other rare diagnoses, such as liposarcoma and fibrosarcoma, must be excludedTrusted Source.

Primary angiosarcoma grows and spreads quickly, so it’s best to start treatment right away. The first treatment is typically surgery to remove the tumor plus a clear margin around it. Depending on the size of the mass, this means breast conserving surgery (lumpectomy) or mastectomy.

Unlike other types of breast cancer, sarcomas of the breast don’t usually spread through the lymphatic system. So, your surgeon may not need to remove regional lymph nodes, but this is decided on a case-by-case basis.

Because primary angiosarcoma is such a rare cancer, there are no hard guidelines for the next steps. Postsurgical treatment may include:

• Radiation therapy: Radiation is a targeted treatment to address any cancer cells that remain after surgery. This can help prevent a new tumor from forming in the same location.
• Chemotherapy: Chemotherapy is a systemic treatment that can destroy cancer cells anywhere in the body. This can help prevent tumors from forming in regional or distant sites.

Sarcomas don’t develop from ductal breast cells, like most other breast cancers. These cancer cells are unlikely to have hormone or HER2 receptors. That means that hormone and HER2-targeted therapies used to treat other types of breast cancer may not be helpful.

Your oncology team will make treatment recommendations based on the specifics of your cancer.

Primary angiosarcoma generally has an unfavorable outlook. This is often due to a delay in diagnosis due to:

• young age at onset
• unusual presentation compared to other types of breast cancer
• its rarity

Some researchTrusted Source suggests that the probability of systemic recurrence is 50%. But surgery followed by chemotherapy and radiation may improve disease-free survival and overall survival. A 2017 studyTrusted Source found that the 5-year survival rate for primary angiosarcoma of the breast is 44.5%.

Because the condition is so uncommon, studies and statistics are lacking. Your own outlook depends on a variety of factors such as:

• whether cancer has spread beyond the breast at diagnosis
• the size of the primary tumor
• tumor grade (how fast it’s growing)
• whether there were clear surgical margins
• choice of treatments
• age

It’s a good idea to discuss outlook with your own oncology team. They can assess your situation and give you a more personal idea of what to expect.