By Dr. Gail Mason, DVM, MA, DACVIM and Kathi Smith, RVT, VTS (Oncology)

Hemangiosarcomas (HSA) are highly aggressive malignancies arising from the lining of blood vessels. These tumors can arise anywhere in the body but most frequently involve the spleen, heart, liver, and skin. About 25% of dogs with HSA have both the spleen and heart involved. Tumor spread occurs most often to the liver, mesentery, lungs, and brain.

Symptoms of HSA in animals are usually attributable to the tendency for HSAs to hemorrhage. If internal organs are involved, the patient may be weak/collapsing, have pale gums, a rapid and shallow respiratory rate and perhaps abdominal enlargement. Emergency intervention (surgery and supportive care) is critical to patient survival.

PATIENT EVALUATION

The first step in treating veterinary patients for HSA is to evaluate general patient health and to assess the extent of the cancer (clinical staging.) This step helps the clinician formulate a treatment plan and allows more precise determination of the prognosis. The evaluation may include the following diagnostics:

• Complete blood count (CBC)
• Serum chemistry panel (assess organ function)
• Urinalysis
• Coagulation profile
• Chest radiographs (x-rays) – (assess evidence of a mass or metastasis
• Ultrasonography – (assess the extent or spread of HSA)

STAGING OF HSA

The prognosis for dogs with HSA is known to be affected by the clinical stage of the disease. In general, this refers to:
Stage I: Localized tumor; no other tumors seen at the time of surgery
Stage II: A ruptured tumor that is confined to the primary site, such as an HSA of the heart or spleen. There may or may not be metastasis present near the site of the primary tumor.
Stage III: A ruptured primary tumor with invasion into adjacent structures plus local or distant metastasis.

TREATMENT OF HSA

Hemangiosarcomas are, unfortunately, highly aggressive tumors and virtually all patients will eventually die from the disease. Currently, these tumors defy cure in veterinary patients. However, a systemic therapeutic approach that involves, 1) surgical resection of the primary tumor and 2) the addition of chemotherapy, can provide remission from cancer.

1. Drugs used for HSA (post-surgery)include:
2. Doxorubicin (intravenous administration)
3. Vincristine (intravenous administration)
4. Cyclophosphamide or Lomustine (oral administration)
5. Non-steroidal anti-inflammatories (oral administration)
6. Tyrosine kinase inhibitors (oral administration)
7. Low-dose daily oral metronomic therapy (oral administration)

The combination of drugs used may differ but the most common treatment interval is about every 21 days. Most often, treatment is continued for at least 6 months.

PROGNOSIS

An exact prognosis for a particular patient with HSA is impossible to predict. However, over fairly large numbers of treated animals published, the following statistics are offered as guides:

HSA PATIENTS IN THERAPY

The quality of life for patients being treated for HSA is generally good to excellent. The chemotherapy drugs are given to minimize toxicity to the patient while still damaging the malignant cells. The disease, even in its late stages, does not appear to cause a pain response in animals. Instead, as the metastatic disease progresses, original symptoms (such as bleeding/anemia/weakness) recur.

Relative to many other animal cancers HSA remains a formidable enemy. The one-year survival rate for patients with surgery alone is 6.25%.  For those undergoing surgery plus chemotherapy, the one-year survival rate is 20%. Newer therapies are close at hand which should greatly enhance control of this illness. Currently, though patient remissions are generally months (vs. years), treatment can be rewarding for both the pet and the family.