As with cancers that affect the liver, cancers that hit the brain and nervous system can be broadly broken down into primary tumors and secondary tumors. A primary brain or nervous system tumor is one that arises from tissues in the brain and nervous system
As with cancers that affect the liver, cancers that hit the brain and nervous system can be broadly broken down into primary tumors and secondary tumors. A primary brain or nervous system tumor is one that arises from tissues in the brain and nervous system, while secondary tumors are those that have traveled from another place (think liver cancer that has traveled to the brain). And, as with cancer in the liver, secondary tumors of the brain are more common in adults than are primary brain tumors. Today we are going to be talking about primary brain tumors in adults. So, grab a copy of those definitions if you need (found here), and let’s get sciency.
When we talk about brain tumors, we often refer to grade rather than stage. This may seem weird at first, but there is a perfectly logical reason. In most cancers, staging talks about how far the cancer has spread, to what structures it has spread, and the size of the primary tumor; however, here is a biggie – brain tumors rarely metastasize to other parts of the body. Here we go again with this ever-present question – why? Our body has some amazing features that are designed to protect itself. One of these is called the blood-brain barrier. This barrier keeps most big nasty bugs (bacteria and viruses) from getting into the brain, and it also keeps great big cells – such as tumor cells – inside and prevents them from spreading.
Now you’re thinking, “Hang on a second. These tumors stay put for the most part, so why are they so dangerous?” The simple answer is that the tumors can affect the processes of the body that are controlled by the region of the brain where they grow. Tumor growth can also increase intracranial pressure, which leads to a whole host of symptoms on its own.
Given this, we talk about grading with brain tumors, using Roman numbers I-IV. Grade I tumors are the least aggressive and least likely to invade nearby brain tissue, while grade IV tumors grow quickly and need the most aggressive treatments. This grading system applies to both adult and pediatric cancers.
Sadly, not a whole lot is known about the causes of brain and nervous system tumors in adults. There are some inherited conditions (such as Li-Fraumeni and von Hippel-Lindau syndrome) that seem to predispose people to these cancers by affecting certain tumor suppressor genes. While we know that cancers arise when gene changes happen within a cell allowing it to grow out of control, scientists don’t have a firm grasp on why these changes happen in the brain, as the brain is protected from the majority of toxicities such as nicotine by the blood-brain barrier.
There are a few other types of brain and spinal cord tumors that occur in adults, but are more prevalent in children, so we will discuss those in my next post covering pediatric brain and nervous system tumors.
As always, much love, many prayers, and abundant blessings to all of the warriors out there!