On March 24, 2009, Dr. West wrote,

A cancer has to grow faster than the tissue around it to become a tumor. Progressive growth is therefore a central feature of a cancer and a critical factor in distinguishing cancerous nodules from benign ones. There is a characteristic "volume doubling time" (VDT), the interval it takes for a nodule to double in volume. It's worth keeping in mind that because a nodule is generally spherical, an increase in the diameter by just 28% (such as a 2 mm increase from 7 to 9 mm) actually represents a doubling of the volume of a nodule.

As you might suspect, there are features of different spolitary pulmonary nodules (SPNs) that makes us more or less suspicious for cancer. The first is the size of the nodule. Looking at multiple series of SPNs, the likelihood of cancer among nodules that measured under 5 mm is generally in the 0-1% range. Nodules in the 5-10 mm range have been found to be cancer in up to about about 28% of cases, with most studies showing the risk of cancer in this range to be one in four or five.