How fast can lung cancer spread or grow? There is no one definite answer to this question. Lung cancer behaves in different ways — the aggressive ones will grow immediately while others do not spread at all — so it is hard and foolish to put a timeline for lung cancer growth.
Still, it is important to note that lung cancer, compared to other kinds of cancer, tends to grow faster and spread earlier. This is specially true for small cell lung cancer which, to borrow the words of cancer.org, “tends to grow and spread quickly, and it has almost always spread to distant parts of the body before it is found”.
Small Cell Lung Cancer (SCLC). Small cell lung cancer comprises about 10% to 15% of all lung cancers. If a patient with small cell lung cancer is left untreated, he or she can die within six months from diagnosis.