A combination of advances in medicine and a decline in smoking are reducing the mortality rates due to cancer. The effect of smoking is large because so many people do it and it is an effective road to the development of lung cancer. It is worth noting that the decrease in cancer mortality rates is in a time when the demographic profile of the population is shifting to include a larger number of older people with a greater risk of suffering cancer, as well as a concurrent rise in the number of overweight and obese individuals, a condition that is also associated with increased risk of suffering many cancers:
The American Cancer Society's annual cancer statistics report finds that a 22% drop in cancer mortality over two decades led to the avoidance of more than 1.5 million cancer deaths that would have occurred if peak rates had persisted. Largely driven by rapid increases in lung cancer deaths among men as a consequence of the tobacco epidemic, the overall cancer death rate rose during most of the 20th century, peaking in 1991. The subsequent, steady decline in the cancer death rate is the result of fewer Americans smoking, as well as advances in cancer prevention, early detection, and treatment.
During the most recent five years for which data are available (2007-2011), the average annual decline in cancer death rates was slightly larger among men (1.8%) than women (1.4%). These declines are driven by continued decreases in death rates for the four major cancer sites: lung, breast, prostate, and colon. Lung cancer death rates declined 36% between 1990 and 2011 among males and 11% between 2002 and 2011 among females due to reduced tobacco use. Death rates for breast cancer (among women) are down more than one-third (35%) from peak rates, while prostate and colorectal cancer death rates are each down by nearly half (47%).
The most common causes of cancer death are lung, prostate, and colorectal cancer in men and lung, breast, and colorectal cancer in women. These four cancers account for almost one-half of all cancer deaths, with more than one-quarter (27%) of all cancer deaths due to lung cancer.