How long does it take for a small cell lung cancer to grow 5 cm?

Approximately 1 year: The speed of tumor growth can be measured by the "doubling time"= time needed to double the volume of tumor. For small cell it can be 2 months. If the tumor was found when it is 1 cm in diameter, it would need 7 doublings times x 2 month = 14 months. If the tumor should start with a single cell, it would take 30 doublings to reach 1 cm in diameter.

Hard to tell: Small cell lung cancer is a rapid growing cancer, but the exact size change in a particular patient is often hard to predict. Several factors affect the growth of tumors in a person, including immune factors and genetic factors. But in general, once small cell lung cancer is diagnosed, it is never just watched, so it is hard to see how fast it will grow.