By the way, doctor: Could flu shots prevent lung cancer?

Q. Do you think flu shots might also prevent lung cancer?

A. First, some basics. Flu results when the in-fluenza virus infects the respiratory system — the throat, the bronchi (breathing tubes) and, often, the lungs. When the virus gets into the lungs, it's called pneumonia. Pneumonia can be caused by the influenza virus alone, or by bac-teria that overcome defenses weakened by the virus. Pneumonia puts a strain on the entire body, because the lungs can't properly replenish the blood with oxygen or remove its waste products when they're battling a viral and bacterial infection. The heart muscle is especially dependent on a full supply of oxygen, so flu shots, by preventing flu and pneumonia, may indirectly help prevent heart attacks and heart failure.