Cedar was in Albuquerque yesterday to visit with a veterinary oncologist. The news is not good. I spoke to Ellie and Mike last night and here is what they found.
As we speculated in the last post earlier this week, the oncologist biopsied the regional lymph nodes and did a chest x-ray. Both were positive for tumor
metastasis. The metastatic squamous cell carcinoma is too advanced for surgery to be a solution. In fact, it is so far along that there is no hope for a complete cure and the strategy will be to slow the growth of the tumors with chemotherapy and try to make Cedar as comfortable as possible during the process. According to Ellie we probably only have a few months left with Cedar. Not what we were hoping for.
Cedar will undergo chemotherapy, but the goal will be to slow the growth of the tumors by attacking the blood vessels that supply the tumor. This type of therapy goes by the name of
continuous low dose anti-angiogenic/ metronomic chemotherapy and up until a few years ago was considered to be experimental.
Conventional chemotherapy in humans usually involves what is called a Maximum Tolerated Dose or MTD given every three weeks or so. Chemotherapeutic drugs target rapidly dividing cells. Cancer cells are rapidly dividing but there are a number of other normal cells like those lining the intestinal tract, bone marrow cells and hair follicle cells that are affected, too.
This is largely the reason behind the nasty side effects associated with conventional chemo. The three week schedule allows for normal cells like bone marrow cells to recover from the damage. Conventional MTD therapy also results in rapid cancer cell adaptation and resistance. That's one reason why so many combinations of chemotherapeutic drugs are given to humans. But, if the goal is to eradicate the tumor, high doses of cyto-toxic (cell killing) drugs are needed and uncomfortable side effects are an unavoidable part of the bargain.
Metronomic chemotherapy differs in that continuous low doses are given over a longer period of time. This means fewer side effects and continuous pressure on the blood vessels helping the tumor grow referred to as the anti-angiogenic effect. Angiogenesis means growth of new blood vessels. The endothelial cells or those rapidly dividing cells that line the inside of new blood vessels are the target of this form of chemo as much as the tumor cells themselves. No blood supply means no or slower tumor growth and that's the goal here. And the low continuous dose does not give the cells of the new blood vessels time to recover as they would have with conventional MTD therapy at three week intervals.
Another advantage is that Ellie and Mike can give these drugs orally at home so Cedar won't have to make frequent tips north to Santa Fe. Cedar is also on antibiotics and anti-inflammatory medication to deal with infection and make him feel better. He goes back in a couple of weeks to see the oncologist. She will evaluate the growth rate of the tumors to see if the therapy is working. That will be an important visit and will give us a better idea of how long we'll have with Cedar.
I know how Mike and Ellie feel having lost our dog of 18 years just last December. When a dog gets older you know in the back of your mind that he won't be around forever. When the
end was near with Darcie I spent more quality time with her. Those were some good days. Bittersweet for sure, but meaningful and satisfying, none the less.