Does brain cancer ever spread to the lungs?

Not likely: Brain tumors usually do not spread to other parts of the body.

Brain cancer: Primary brain cancers - cancer that originated from the brain itself- do not spread outside the brain. Brain metastases- cancers that spread to the brain from a primary cancers located outside the brain- is way more common than primary brain cancer. For instance, lung cancer, breast cancer spread commonly to the brain.

Almost never: Tumors that start in the brain (such as glioma- the most common primary tumor ) almost never metastasize outside the brain, to the extent that they are reportable as case reports.