As Tufts researchers work to develop a scoring system to help determine whether a splenic mass is a deadly cancer or a highly curable hematoma before the owner makes a decision to have surgery performed, they have also confirmed that the prognosis for dogs with hemangiosarcoma is tied closely to the cancers stage. When veterinarians talk about a cancer being stage 1, 2, or 3, they are referring to where the cancer is in the body. (Grading a cancer, on the other hand, is about what the disease looks like under a microscope.)
Stage 1. This means the dog has the cancer in her spleen but the mass has not bled and theres no evidence of it in the liver or any other tissue. It has spread – splenic hemangiosarcoma metastasizes almost 100 percent of the time. We just cant detect it, says Tufts soft tissue surgeon John Berg, DVM. (With some other cancers in dogs, stage 1 means the tumor truly has not spread and can be cured with surgery.)
Stage 2. As with stage 1, the veterinarian is not able to detect that the cancer has spread. Whats different is that in this stage, the cancer has bled into the abdomen.
Stage 3. The spread of the cancer, with or without bleeding, is evident upon ultrasound or chest x-rays. This can be seen prior to surgery to remove the cancerous spleen.
Stage is highly predictive of outcome, Dr. Berg says. For dogs that present with stage 1, median survival time approaches 6 months. And maybe a third of those dogs live beyond a year – without chemo, just surgery. So the surgery for a stage 1 cancer definitely has added value.
The most common stage is stage 2, he adds. Thats where the median survival is two to three months.
At the other end, he says, if theyre stage 3 with visible metastases, then they live a little less than a month, on average. You probably wouldnt recommend surgery for a dog whos stage 3. The problem is that our ability to determine whether a dog is stage 3 is limited, and thats because the most common place for the cancer to spread is to the liver. Multiple nodules in the liver could indicate the metastasis of the cancer, but it can also be a benign condition, especially in older dogs, called nodular hyperplasia.
We could biopsy the nodules with a needle, says Dr. Berg, but most dogs need emergency surgery, and the biopsy results would take a few days to come back. So we need to go forward with surgery without knowledge of whether liver nodules are benign or malignant. We remove the spleen and biopsy any liver nodules at the same time. If they come back benign, but the splenic mass proves to be a hemangiosarcoma that has not yet bled into the abdomen, chances are that you have given your dog close to 6 months of good-quality life.