Changes in cancer rates when health behaviors shift [includes video]

Chart shows lung cancer incidence broken down by race

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Detecting cancer outcomes in the U.S. population following major changes in health behaviors often takes decades, as opposed to years. This is because many cancers are slow growing and don’t manifest themselves in a detectable way until years after the event or events that may initiate them. This delay in changing rates is particularly true for mortality outcomes in women for two cancers—lung and breast—affected by significant changes in health behaviors in the past 10 to 20 years.

Shifts in smoking patterns, both initiation and cessation, are fairly easy to track, and have been linked to a number of seminal events. Men started smoking at increasing rates during World War II and didn’t begin noticeable cessation efforts until after the U.S. Surgeon General’s announcement linking smoking to lung cancer in the 1960s. Even then, it took almost four decades to see a drop in death due to lung cancer for men, and indeed, it was not until the end of the 20th century that such drops were noticeable by statisticians. By contrast, women didn’t take up smoking as much as men until the 1960s, when cigarette manufacturers started designing and heavily promoting products for women. In part because they began smoking in large numbers later in the 20th century, cessation of smoking by women occurred years after men began to quit.

Image shows incidence rates for prostate, breast, lung, colorectal cancers and melanoma

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With the release of 2009 data from NCI’s SEER program on April 16, 2012, experts point to a continuing statistically significant decline in lung cancer mortality for women. This turning point was particularly important, as lung cancer is the No. 1 cancer killer for both men and women. Lung cancer cases make up nearly a quarter of all cancers deaths in the U.S.  A continuation of the trends showing a drop in lung cancer mortality for both sexes would indeed be good news for the health of the nation.

Chart shows mortality rates for cancers of the lung, colorectal, breast, pancreas and prostate.

click to enlarge

The other cancer in women that has been noticeably affected by a change in health behaviors this century is breast cancer. When NIH released the first results from the Women’s Health Initiative in 2002, the study pointed to an increased risk for breast cancer among women who used hormone replacement therapy. That news caused many women to stop taking hormone replacement drugs, and in 2003 the SEER program reported a marked decrease in breast cancer incidence.  Now, almost 10 years later, the SEER data for 2009 show no appreciable change in incidence of breast cancer since 2003.  Whether the decline in HRT use has affected breast cancer mortality rates is still unclear, in part, due to high survival rates experienced by many breast cancer patients.

In the accompanying video interview, Kathy Cronin, Ph.D., acting chief of NCI’s Surveillance Research Program, discusses lung and breast cancer results from the SEER 2009 release, as well as other outcomes reported in this year’s release.

For more information on using the data released as part of SEER’s annual Cancer Statistics Review, see our article from last year’s release:  Need stats? How to find the most up-to-date cancer statistics

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