Cancer rates have been rising steadily since the 1940s. But this is mostly true in Western life-style societies. By understanding how this happened, we can all learn to protect ourselves better.
A Cancer Epidemic Started in 1940
Cancer rates have been climbing steadily since 1940. This is not due simply to the increase use of screening tests or the aging of our population: cancer has been rising in children and adolescents at a rate of 1% per year in the past 25 years. And cancers that have no screening test (lymphomas, pancreatic and testicular cancers for example) have been increasing as fast or faster than those that do (breast, colon, prostate).
The most common cancers in the west are rare in some other countries. In certain regions of rural China in the 1980s, for example, WHO researchers using the same screening tests we use in the west were not able to find any cases of breast cancers. They were told by local physicians "it's a disease of rich women! You’ll find it in Hong Kong, but not here."
When Chinese women immigrate to the US, their risk of breast cancer becomes that of American women within one or two generations. The same is true for Japanese men and prostate cancer. Asians are not protected by their genes, but by their life-style.
A Watershed in 1940: Five causes of a cancer epidemic
Five major aspects of our life-style have changed since 1940 and contribute to the progression of cancer:
1. The massive increase of sugar consumption
We went from 12 lbs of refined sugar per person per year in the 1800s to 154 lbs per person per year in 2000.
Cancer cells feed primarily on sugar. To detect where a tumor may be present in the body, we use PET scans that simply measure where radioactive sugar accumulates.
2. The change in the way we feed animals that feed us
Animals used to feed on grass and seeds rich in omega-3 fatty acids that slow the growth of cancer. Hence, meat, milk, cheese, butter, and eggs were all rich sources of omega-3 fatty acids. Now that animals are fed in feed-lots with corn and soy, omega-3s have practically disappeared from our common foods. Eggs my grandmother used to feed me on the farm I was raised on were a genuine "health food", filled with the omega-3 DHA necessary for the growth of a child's brain. Today’s supermarket eggs have practically no DHA and it has been replaced with the pro-inflammatory omega-6 arachidonic acid (AA).
A diet rich in omega-6 fatty acids is associated with a markedly increased risk of breast cancer. As omega-6s stimulate inflammation in the body, they are likely to feed the growth of many other types of cancer too.
Trans-fats, introduced widely in the 1960’s, are now present in almost all industrial foods (pizza, cookies, French fries etc.). They are thought to increase the risk of breast cancer by a factor of 2. A Dutch government report of 2007 estimates that that the number of deaths due to trans-fats in that country exceeds that due to motor vehicle accidents.
3. The introduction of chemicals in all aspects of life
DDT was invented just before WWII. Many common herbicides and pesticides mimic the effects of estrogen hormones in the body. They can stimulate the growth of an existing tumor. In 2005 the CDC found 149 toxic chemicals in the blood and urine of American of all ages that were tested. In 2003 the University of Seattle tested pre-schoolers who eat conventional (non-organic) foods. The level of pesticide residue in their urine was high. For some of them, it exceeded by a factor of 4 the limit recommended by the Environment Protection Agency. Children eating organic diets (70% organic or better) had practically none.
4. The massive reduction in our physical activity
Do you know anyone whose grand-parents did not walk to school? How many children do you know today who walk more than 10 minutes to go to school? Something powerful has happened to our relation to physical activity. We are the most sedentary humans that ever existed.
The risk of a relapse from breast cancer is 50% less in women who walk 30 minutes six times a week. Physical activity is a highly effective protector from cancer that we have eliminated from our lives.
5. The disorganization of our social support networks
We Americans now move on average every 5 years. This means that we change neighbors, often friends, and get further and further away from our aunts and uncles, our parents, and our siblings.
In times of major stress, the most effective protection from adverse psychological and physical effects on our body comes from the strength of our intimate relationships. How strong are they today when we no longer live near each other? Twenty-five percent of us say that we have no one in whom we can confide.
One Australian study found that women with a major stressor in their life and no intimate support had 9.5 times more chances of developing breast cancer.
The encouraging part in this sad picture of an epidemic is that each one of us can start to reverse these societal changes in our own life. We can decide to nourish balance, to stimulate health, in us and around us. We can opt for a new way of life. And in doing so, we simultaneously help prevent cancer if we are cancer free, and strengthen our bodies if we already have it.
©2008 David Servan-Schreiber, MD, PhD