Hemangiosarcoma

Quick Facts at a Glance

• 43% of dogs with splenic masses have hemangiosarcoma (HSA)
• 50% of dogs with splenic HSA are in DIC (disseminated intravascular coagulation or inability to clot blood) at presentation
• Average post-splenectomy survival times reported are 49-90 days
• Liver biopsy is essential to differentiate between liver metastasis (spread) and benign hyperplasia (increased tissue growth)
• Shepherds and northern breeds are at increased risk for developing HSA
• Stage I cutaneous HSA can be cured with aggressive surgical resection
• X-rays of the lungs are required to rule out pulmonary metastasis (tumors in the lungs)
• Cardiac HSA is the most common cause of pericardial effusion (fluid surrounding the heart) in dogs
• HSA in cats is rare but occurs most commonly within the abdomen or subcutaneous tissue (under the skin)

Cutaneous hemangiosarcoma: stage is critical!

Cutaneous hemangiosarcoma (cHSA) is staged based on the depth of invasion into the skin and underlying tissue. Stage I cHSA occurs as several superficial firm, raised, dark purple nodules located on the abdomen, back legs or prepuce (sheath that contains the penis). Treatment requires wide surgical excision but results in a cure in cases where tumor-free surgical margins are obtained. Average survival time post-resection is 780 days.

Stage II and III cHSA are more aggressive, having invaded into the hypodermal (under the skin) tissue and underlying musculature, respectively. These tumors often appear as bruise-like lesions. They can be firm or soft, ulcerated and bleeding. Complete surgical resection is often difficult. Recurrence is common and metastasis occurs in 60% of cases. Average survival time with complete surgical resection is 275 days. Chemotherapy is recommended at the time of surgical resection to prolong survival time.

Splenic HSA: How common is DIC?

Because of the severe microangiopathic hemolytic anemia (decrease in red blood cells) that results from splenic HSA, 75% of patients are thrombocytopenic (decreased platelet count resulting in difficulty clotting blood) at the time of presentation, with 2/3 of these in DIC. The reported death rate during the pre and post-operative time period ranges from 50-80%, secondary to complications from DIC. Survival times are significantly improved when DIC is recognized early and aggressively treated. Clotting profiles including platelet counts should be performed before and after surgery to determine the severity of DIC. Treatment of DIC consists of fresh whole blood or packed red blood cells, fresh or fresh frozen plasma, high volumes of intravenous fluids, heparin and coumadin. These measures increase the post-operative survival rate to 85-90%. It is very challenging to control DIC if gross disease is not eliminated at the time of surgery.

Splenic HSA: Does chemotherapy help?

Survival time post-splenectomy rarely surpasses 3 months due to the high rate of metastasis to the liver and lungs. In fact, 60% of dogs have gross metastatic disease to these locations at the time of presentation. In patients without identifiable liver metastasis or mesenteric (web of tissue that holds the abdominal organs in place) involvement, chemotherapy is recommended to prolong survival time. Adriamycin, vincristine and cyclophosphamide have been shown to increase average survival time following splenectomy from an average of 65 to180-271 days. These drugs are well tolerated, with the majority of dogs experiencing above average quality of life. Despite the improvement in survival times, few dogs survive past 1 year with all eventually succumbing to metastatic disease.

Occasionally, splenic masses are found incidentally on routine abdominal ultrasound. Splenectomy at this early stage can result in long-term remission (greater than 1 year). In older patients at risk for splenic HAS, routine abdominal ultrasound is part of a twice-annual wellness evaluation.

Cardiac HSA: Chemotherapy is essential!

Cardiac HSA is the most common cause of pericardial effusion in the dog. These tumors are generally located in the wall of the right atrium and bleed profusely into the pericardial sac (encloses the heart). Surgical resection has been reported to be associated with an average survival time of 6 days, but can be very helpful in a small percentage of dogs. Most dogs are euthanized at the time of surgery because the tumors are not resectable. Most patients present with some degree of circulatory failure that can be quickly relieved with pericardiocentesis (draining the fluid from the sac that encloses the heart) and intravenous fluid therapy. However, due to the persistent bleeding of the tumor, effusion generally recurs within 5-7 days.

In cats too?

The spleen, intestines, mesentery (web of tissue that holds abdominal organs in place) and subcutaneous tissue (under the skin) are common sites for feline HSA. Metastasis is common, occurring in 67% of cats at the time of presentation. Metastasis is most common to the liver, lymph nodes and myocardium (heart muscle). The subcutaneous form has a better prognosis if complete surgical resection can be achieved.

What does the future hold?

Hemangiosarcoma is a disease that may lend itself well to treatment with angiogenesis inhibitors (drugs that inhibit blood vessel formation). This group of drugs includes thalidomide, endostatin, angiostatin and soluble VEFG-receptor (soluble vascular endothelial growth factor receptor). While these drugs would not likely result in tumor regression, they may control the bleeding and associated DIC thereby giving other forms of treatment (i.e. chemotherapy) more time to work.

We currently have a study for dogs with splenic hemangiosarcoma. This is a funded study for patients with histologically confirmed hemangiosarcoma localized to the spleen only. Patients are eligible for entry into the study 7-14 days after splenectomy. They are randomized into one of two groups: treatment with adriamycin (chemotherapy) alone or a combination of angiogenesis inhibitors. The study covers the cost of all diagnostic tests and treatment once entered into the study, until progressive disease or study completion at one year. Entry criteria are: confirmed diagnosis of splenic hemangiosarcoma with no liver, mesentery or lung involvement, normal blood work and urinalysis, good recovery from surgery, no concurrent illness, no steroids or concurrent chemotherapy, no prior treatment with adriamycin and no concurrent treatment with non-steroidal anti-inflammatory medications. There is an entry fee of $500.