How much of the decrease in cancer death rates in the United States is attributable to reductions in tobacco smoking?
- Department of Epidemiology and Surveillance Research, American Cancer Society, Atlanta, Georgia, USA
- Correspondence to: Michael J Thun MD, Department of Epidemiology and Surveillance Research, American Cancer Society, Atlanta, GA 30229-4251, USA;
Reductions in tobacco smoking are a major factor in the decrease in cancer mortality rates
It is difficult to quantify the benefits of large scale, preventive interventions taken in the past, because the size of the benefit depends on assumptions about what might have happened had there been no intervention. For example, if one wishes to measure how much of the decrease in cancer death rates in the United States is attributable to reductions in tobacco smoking, the most conservative approach is to consider only the time period during which cancer death rates actually decreased. This limits consideration to the observed decrease in overall cancer death rates that occurred among men (but not women) between 1991, the year when the age standardised cancer death rate peaked in the overall US population, and 2003, the most recent year for which final mortality data are currently available.1 While it seems prudent to base the estimate only on observed data and only during the time period when cancer death rates actually decreased, this approach greatly underestimates the full impact of reductions in smoking on cancer death rates over the preceding three decades. It fails to consider first the attenuation of the increase and then the levelling off of the death rates from smoking related cancers that occurred before their actual decline. A different approach is needed to take into account what would likely have happened to cancer death rates over the last half century, had the health community not intervened to discourage cigarette smoking.
We used both of the approaches mentioned above to estimate how much reductions in tobacco smoking have contributed to the decrease in mortality rates from cancer in the United States. We also used a third, related method to consider the impact of smoking reduction on the number of …