Ask an Expert: Lung cancer growth and spread

Q: "How long does it take for lung cancer to develop, and can I determine when mine started growing?"

Answer from John R. Handy, Jr. , M.D., co-director of Providence Thoracic Oncology Program and director of  Providence Thoracic Surgery Program

Currently there is no test that can tell us how long a lung cancer has been growing or when it started. The rate of cancer growth and spread varies from person to person and between types of cancer (breast and prostate cancer, for example). Lung cancer, unfortunately, tends to be a fast-growing, early-spreading cancer.

There are many steps in the development and growth of lung cancer. First, changes must take place in a cell or group of cells that lead to uncontrolled division and growth. It takes at least 30 divisions of one cancer cell to create a tumor that is 1 centimeter in size (about half an inch). That is the smallest size likely to be seen on an X-ray.

It takes about three to six months for most lung cancers to double their size. Therefore, it could take several years for a typical lung cancer to reach a size at which it could be diagnosed on a chest X-ray.

With this in mind, it is likely that your cancer has been developing for a number of years but was too small to produce symptoms or to be seen on an X-ray.

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