25 June 2008
Cancer Deaths Declining in Developed Countries
United States, international organizations coordinating research efforts
Washington -- News about the dangers of infectious diseases like HIV/AIDS and avian influenza capture headlines around the world, but the Number 1 cause of human deaths worldwide is a chronic disease -- cancer.
According to the World Health Organization (WHO), 70 percent of cancer deaths in 2005 occurred in low- and middle-income countries, where cancer rates are on the rise. But, due to dramatic advances in medicine, cancer mortality rates in the world’s developed countries, like the United States, have been declining since the early 1990s. (See “Global Causes of Death Move from Infectious to Chronic Diseases.”)
The International Agency for Research on Cancer (IARC) and the National Cancer Institute (NCI), one of the U.S. National Institutes of Health, are working to combat this deadly disease.
IARC, founded in 1965 and part of WHO, has the mission of identifying all the causes of cancer. According to its Web site, 80 percent of cancers are caused by environmental factors and therefore are preventable. The organization’s focus is on prevention and early intervention, rather than treatment. The high cost of cancer arises mainly from treatment.
The more than 100 different kinds of cancers can occur in any part of the body. The four most common types of cancer deaths worldwide are from lung, stomach, liver and colon cancers.
All cancers are the product of a single cell that, for a variety of reasons, begins to multiply unchecked. Normal cells undergo a tightly regulated life cycle including growth and death, but sometimes these processes are disturbed, resulting in a cancer cell. The mass of cancer cells that results from this unregulated division of cells is called a tumor.
Tumors form first in the part of the body where the original cell became tumorigenic (tumor-producing). At this stage, the cancer is highly treatable. Sometimes cells from the tumor spread to other parts of the body in a process called metastasis, making the cancer more difficult to treat.
Cancer treatment can include surgery, radiation therapy and chemotherapy. The aim of surgery is to remove the tumor and thus the bulk of cancer cells.
Radiation therapy -- the application of high doses of radiation -- slows or stops cancer cell growth but also can affect healthy cells, leading to unpleasant side effects.
Chemotherapy uses drugs specifically selected for a given type of cancer and situation to reduce and exterminate the cancer cells. Side effects from cancer drugs are common. These therapies can be used alone or in combination. If these therapies are successful, the cancer is said to go into remission; however a chance of a relapse, or reoccurrence of the cancer, remains.
Cancer is common but not inevitable. About 40 percent of all cancer deaths can be prevented by refraining from tobacco, keeping a healthy diet and participating in regular exercise, according to WHO.
MOLECULAR BASIS OF CANCER
IARC focuses mostly on carcinogens (cancer-causing agents) in the environment, but another project is looking into the cancer cell, at the genes, to uncover cancer’s secrets.
A joint initiative by the National Cancer Institute and the National Human Genome Initiative called the Cancer Genome Atlas is using the technologies developed by the Human Genome Project to understand the molecular basis of cancer on a genome-wide scale. The genome is the set of all genes that make up an organism.
The Cancer Genome Atlas aims to be a map of all genes involved in cancer. The types of cancer chosen for study are brain, lung and ovarian. Together, these cancers account for more than 210,000 cancer cases each year in the United States.
The project is taking place at several different research laboratories around the United States. Benjamin Tycko, a professor at Columbia University, received a grant to study a particular type of genetic change -- an epigenetic change -- that can occur over the course of one’s life. Tycko studies an epigenetic change called DNA methylation, which sometimes can lead to cancer.
“By mapping the patterns of DNA methylation in cancer cells, we can pinpoint genes that are crucially involved in cancer initiation and progression. These genes, and the proteins that they produce in the cell, can then be tested as targets for anti-cancer drugs,” says Tycko. “In addition, screening body fluids such as the blood for genes that are abnormally methylated at a high frequency in specific types of human cancers can be used to diagnose the cancer at a very early stage -- thereby increasing the likelihood of a cure.”
NANOTECHNOLOGY
Another project being undertaken by the NCI is the Alliance for Nanotechnology in Cancer. According to the project’s Web site, “nanotechnology can provide the technical power and tools that will enable those developing new diagnostics, therapeutics, and preventives to keep pace with today’s explosion in knowledge.”
One of the projects involves the use of nanoparticles, which are tiny spheres that can be loaded up with cancer drugs. NCI chemist Jennifer Hall is developing nanoparticle therapies.
“Cytotoxic drugs can be attached to a nanoparticle so that the nanoparticle carries it … to tumor tissue,” says Hall. There are already a few federal Food and Drug Administration-approved nanotechnology-based cancer drugs on the market, with more expected in the next few years.
More information on cancer research, statistics and treatment is available on the Web sites of the National Cancer Institute and the American Cancer Society.
