Probably the most feared cancer diagnosis is that of any cancer metastasizing (spreading) to the brain. Not only is any brain infection or tumour likely to cause severe neurological problems such as paralysis or loss of memory, but a brain cancer is very difficult to treat in any hospital in the world, not just NHS.

The problem with treating many conditions is simply that the body defends the brain with something called the blood-brain barrier (BBB) which tries to protect the brain by keeping bad substances makes it difficult to transport drugs to the site via the bloodstream.

Brain cancer numbers.

How common is this spread of another cancer such as breast cancer to the brain? The American Brain Tumor Association estimates that each year between 100,000 and 170,000 Americans are diagnosed with cancer that has spread to the brain.

Lung cancer is another variety which often metastasizes to the brain but malignant melanoma is probably the biggest threat because it also spreads to the brain and is so often diagnosed late in the progress of the disease and therefore most likely to already have spread to other organs by the time it is diagnosed.

Until very recently a brain cancer diagnosis was almost certainly terminal even if the cancer itself would be treatable if it were in another part of the body.

Because of those numbers and the increasing incidence of malignant melanoma, a great deal of research goes into finding a way to get existing life-saving drugs past the blood-brain barrier (BBB).

Antidepressant lowers BBB

Obviously having a cancer diagnosis can be depressing but a new study by the US National Institute of Health (NIH) shows that a common antidepressant, amitriptyline, doesn’t just make the patient feel better, it actually lowers the BBB temporarily in rats.

Of course, the fact that it works in rats doesn’t guarantee it will work in humans but the researchers are very excited by this discovery of any drug which lowers the BBB in any animal.

Among the diseases or conditions which can probably be treated if only the BBB didn’t block drugs are brain-centered conditions including epilepsy, stroke, ALS (Lou Gehrig's Disease), even depression.

The BBB, how does it work?

Just what is the blood-brain barrier (BBB)? This critical part of the blood system protects us from many infections but also makes it nearly impossible to treat most infections or tumors. The way it works is that blood vessels in the skull are different from those in the rest of the body. Brain blood vessels have a lining of a special protein known as P-glycoprotein which keeps toxins and medicines from entering the brain.

Think of these endothelial cells as a kind of strainer which is designed to let nutrients and hormones through to the brain but not poisons or bacteria.

Since many drugs, especially medicines used to treat cancer, are actually poisons, we aren’t surprised that the BBB blocks treatment.

Traditional cancer tumour treatments which could be used on the brain were limited to surgery or whole brain radiation. There are also more exotic treatments such as implanting a radioactive chip in the tumor. But while those are perfectly acceptable for cancers located in other parts of the body, when applied to a brain cancer they can dramatically degrade the quality of life by ruining memory, cognitive skills, attention span, and other important functions.