Lung cancer and brain connection

Dear Dr. Roach: I read your recent article about small cell lung cancer and the connection to the brain. My husband died from small cell lung cancer in 2014. He was a very clear thinker, but gradually acted very strangely over the two years he lived with the disease.

Can the cancer actually START in the brain and metastasize into the lungs? How long does it take to wander from the lung to the brain? — A.

I am sorry about your husband. It can take a very long time before you can look back on the life of a person you loved with more joy and less pain.

Cancers often start in one organ and spread to another. Depending on the type of cancer, the pattern is usually reliable. However, there are some tumors that metastasize (this means to spread) in ways that are surprising. For example, stomach, intestinal and even breast cancers can metastasize to the ovary, which is then called a Krukenberg tumor.

Most brain cancers in adults have spread from other parts of the body. Primary brain cancers, those that originate in the brain, can spread from the brain, but when they do, it is most commonly from its origination point to other parts of the brain or to the spine. For glioblastoma multiforme, the most common and deadly form of primary brain cancer, only 0.2% will spread outside the brain.

In your husband’s case, the fact that it was small cell cancer absolutely confirms its origin in the lung. It would be extremely rare for a pathologist to miss the diagnosis. Seventy percent of small cell lung cancer has already spread outside the lung by the time it is diagnosed: The liver, brain, adrenal glands and bone marrow are common sites for metastatic disease. Had his doctors suspected metastatic disease to his brain, he would likely have been recommended radiation therapy to the brain.