How often should one have a spiral ct scan to check for lung cancer?

Rarely: A ct scan is not a screening exam. You only do one when you are looking at something with high suspicion. That is a lot of radiation to be routinely exposed to when you are screening for cancer.

New study: Recent low dose screening ct trial suggests that heavy smokers be screened and was associated with better overall survival.

Depends: Ct-scan screening for lung cancer is appropriate for specific patients that meet certain criteria. See this link: http://www.Cancer.Net/publications-and-resources/what-know-ascos-guidelines/what-know-accp-and-asco-guideline-lung-cancer-screening/recommendations-lung-cancer-screening.