NCI Dictionary of Cancer Terms
The NCI Dictionary of Cancer Terms features 8,311 terms related to cancer and medicine.
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- pack year
- listen (pak yeer)
- A way to measure the amount a person has smoked over a long period of time. It is calculated by multiplying the number of packs of cigarettes smoked per day by the number of years the person has smoked. For example, 1 pack year is equal to smoking 1 pack per day for 1 year, or 2 packs per day for half a year, and so on.