How does cancer in your brain form?

The cancer cells break away from the primary tumor and travel to the brain, usually through the bloodstream, then commonly go to the part of the brain called the cerebral hemispheres or to the cerebellum. Cancer can also spread to the spine (metastatic spine tumors).

Smoking damages the respiratory system by inhalation of a foreign substance, that is absorbed and residue is left behind on our lungs sponge like substance. the gas that is inhaled also increase your blood pressure and dilates your blood vessels. also the process of inhaling and exhaling the smoke it causes irritation to the throat and mouth. smoking can cause lung cancer and other respiratory and circulatory diseases.