ATLANTA--A new American Cancer Society study finds progress in reducing cancer death rates is evident whether measured against baseline rates in 1970 or in 1990. The study appears in the open access journal PLos ONE, and finds a downturn in cancer death rates since 1990 results mostly from reductions in tobacco use, increased screening allowing early detection of several cancers, and modest to large improvements in treatment for specific cancers.
Temporal trends in death rates are the most reliable measure of progress against cancer, reflecting improvements in prevention, early detection, and treatment. Although age-standardized cancer death rates in the U.S. have been decreasing since the early 1990s, some reports have cited limited improvement in death rates as evidence that the "war on cancer", which was initiated in 1971, has failed. Many of these analyses fail to account for the dominant and dramatic increase in cancer death rates due to tobacco-related cancers in the latter part of the 20th century.
To investigate further, researchers led by American Cancer Society epidemiologist Ahmedin Jemal, Ph.D., used nationwide cancer mortality data for the years 1970 through 2006 from the SEER*Stat database, which defines major cancer sites consistently over time in order to facilitate reporting of long term mortality trends. They found for all cancers combined, death rates (per 100,000) in men increased from 249.3 in 1970 to 279.8 in 1990, and then decreased to 221.1 in 2006, yielding a relative decline of 21% from 1990 (peak year) and a drop of 11% since 1970 (baseline year). Similarly, the death rate from all-cancers combined in women increased from 163.0 in 1970 to 175.3 in 1991, and then decreased to 153.7 in 2006, a relative decline of 12% and 6% from the 1991 (peak year) and 1970 rates, respectively.
You can get a much better picture of the trends by looking at the slideshow graphs associated with the research report. Colorectal cancer has been in decline since 1970. But other cancers didn't start declining until the mid 1990s.
You can read the full text of the report for more details. Death rates declined for a large assortment of cancers including those of the stomach, bladder, brain, kidney, and Non-Hodgkin lymphoma.
During the most recent time period, death rates decreased for cancers of the oral cavity, stomach, bladder, kidney, brain, and Non-Hodgkin lymphoma, and leukemia in both males and females and for cancers of the esophagus and ovary and melanoma and Hodgkin lymphoma in females. In contrast, rates increased for esophagus cancer and melanoma in men, liver cancer in both men and women, and pancreas cancer in women. Death rates stabilized for pancreatic cancer and Hodgkin lymphoma in men and for cervix and corpus and uterus cancers in women. Notably, the 2006 death rates for Hodgkin lymphoma in men, cervical cancer in women, and stomach cancer in both men and women were less than one-third of the 1970 rates.
Many factors contribute to these trends. Early detection, reduced smoking by men, and better treatments all have worked to lower death rates. Hepatitis C, obesity, and a surge in smoking by women all contributed to delaying declines or causing surges in some cancer types.
Most treatments for cancer are still far too crude. Some of the big advances in the next 20 years will come in the form of delivery methods that much more precisely target just the cancer cells with toxins. Also, pieces of regulatory RNA delivered into cells will instruct cancer cells to either die or at least stop dividing.
|Share |||Randall Parker, 2010 March 10 10:52 PM Aging Cancer Studies|