How is the excess risk from heavy smoking calculated when considering lung cancer deaths?

• A. 2.27 + 0.07
• B. 2.27 - 0.07
• C. (2.27 - 0.07)/2.27
• D. 2.27 * 0.07

Answer: (B)

To understand how the excess risk from heavy smoking is calculated when considering lung cancer deaths, it's important to recognize what the figures represent. In this context, the value of 2.27 is likely referring to the relative risk of lung cancer associated with heavy smoking compared to non-smokers. The value of 0.07 could represent the baseline risk of lung cancer in non-smokers.

The calculation of excess risk involves determining how much more likely heavy smokers are to develop lung cancer compared to non-smokers, while also taking into account the baseline risk of lung cancer in the overall population. By subtracting the baseline risk (0.07) from the relative risk (2.27), you can isolate the additional risk attributed specifically to heavy smoking.

Thus, subtracting 0.07 from 2.27 allows you to find the excess risk of lung cancer deaths that can be attributed directly to the high levels of smoking, providing a clearer picture of the impact that heavy smoking has on lung cancer incidence. This method ensures that you are not overestimating the risks by including individuals who would have developed cancer regardless of their smoking status.